What happened

On 2 August 2014, the pilot prepared the C206, VH-TND for the first of three scenic flights. As the aircraft departed from runway 03, the wind was from the east at about 8 knots.

On return to Rawnsley Park, the pilot conducted a straight in approach onto runway 21. The pilot did not compensate for the crosswind during the flare and touchdown, and after landing retracted all stages of flap, and applied light pressure to the brakes.

The aircraft then began to veer to the left. The pilot applied right rudder, but was unable to correct the situation, so initiated a go-around. During the go-around the horizontal stabiliser struck a shrub, causing significant damage to the aircraft.  The pilot lowered the aircraft nose. After clearing a small tree, the pilot raised the aircraft’s nose in an attempt to clear the windsock.

Moments later, the aircraft spun rapidly to the left and collided with the ground. The pilot shut down the aircraft and assisted the passengers to exit. One passenger sustained serious injuries and another sustained minor injuries. The pilot was not injured. The aircraft was substantially damaged.

It appears that an incorrect technique was applied during the crosswind landing and subsequent go-around. The suddenness of the unexpected events during an otherwise routine exercise caught the pilot unprepared, resulting in a loss of situational awareness. 

The Civil Aviation Safety Authority (CASA) has available on their website a booklet and DVD looking at situational awareness. Chapter 6 specifically looks at Losing Situational Awareness.

This is available through CASA’s online store: www.casa.gov.au

The European General Aviation Safety Team (EASA) published a Safety Promotion Leaflet on Decision Making for General Aviation Pilots. This leaflet suggests that many accidents are the result of pilot action, including the decisions that they make.

This brochure is available at www.easa.europa.eu

Aviation Short Investigations Bulletin - Issue 36

What happened

On 1 August 2014, at about 0935 EST, a Reims Aviation F406 aircraft, registered VH-EYQ, departed Emerald, Queensland, on an aerial survey task with a pilot and navigator on board. The aircraft was fitted with an oxygen system to allow unpressurised operations above 10,000 ft. The pilot tested the oxygen system for normal operation prior to the flight.

During the climb, the pilot turned on the aircraft oxygen supply and connected and donned his oxygen mask. The pilot then monitored his blood oxygen saturation level on an oxygen pulse meter as the aircraft continued to climb, and monitored his flow of oxygen by reference to a flow indication in the supply tube. All appeared normal until about flight level 180, when the pilot noticed that his blood oxygen saturation level had fallen significantly.

The pilot attempted to increase the amount of oxygen he was receiving by making an adjustment to his oxygen system controller, but the accuracy with which he was controlling the aircraft deteriorated, and his speech became slurred. The navigator encouraged the pilot to maintain control and descend, and air traffic control prompted the pilot to ensure that he was receiving an adequate supply of oxygen. The pilot was ultimately able to reconnect a fitting in his oxygen supply system that had become disconnected. When he reconnected the fitting, the pilot sensed almost immediate relief and was able to make a controlled descent. The crew returned to Emerald for an uneventful landing.

This incident highlights the importance of careful attention to aircraft oxygen systems, particularly with respect to connecting and monitoring oxygen system performance. Pilots are reminded that hypoxia is an insidious condition and the time of useful consciousness is often very limited. A prompt and decisive response to the first indication of an oxygen supply problem is imperative.

Aviation Short Investigations Bulletin - Issue 39

What happened

On 13 June 2014, the pilot of a Bell 206 helicopter, registered VH-KSV, conducted a flight from Mitchell Plateau campground, Western Australia, to a remote site about 30 NM away to collect passengers.

Approaching the site, the pilot conducted an orbit of the area at about 300 ft above ground level (AGL) to assess the landing area. As the helicopter descended over trees, the pilot observed that the helicopter was slightly higher than optimal for the approach. From a high hover, at about 10 ft AGL, the pilot continued to lower the helicopter slowly and elected to land towards the rear of a rocky sandstone platform to remain clear of the waiting passengers.

The right landing skid touched down first and only the front portion of the landing skids was in contact with the platform, with the right skid was sitting on a rock. The pilot attempted to raise the helicopter back into the air to relocate to a better landing position, but as he raised collective, he felt the helicopter start to roll and he quickly lowered the collective. The helicopter tipped backwards off the edge of the rocky platform and slid about 2 m down the slope before coming to a halt.

After shutting down the engine, the pilot inspected the helicopter and found substantial damage to the landing skid, a hole in the main rotor blade where it had struck the wirestrike cutter, and damage to the tail boom.

This incident highlights the importance of assessing a landing site thoroughly and conducting the approach to land so as to optimize the opportunity of sighting any potential hazards.

Aviation Short Investigations Bulletin - Issue 34

What happened

On 31 May 2014, a Beech Aircraft Corp D17-S, registered VH-FNS, was conducting a private flight, departing Crooked Brook landing area for Geraldton airport, Western Australia, at about 1322 Australian Western Standard Time. The pilot was the only person on board. The flight was conducted in visual meteorological conditions.

After departure, the pilot tracked in a northerly direction and climbed to an altitude of about 2,500 ft above mean sea level. About a minute after setting the engine to cruise power the pilot felt a violent vibration with an associated decrease in engine power. The pilot described the engine as ‘surging’ and ‘back firing’. The pilot conducted initial troubleshooting and was unable to identify a reason for the engine malfunction. The vibration ceased and the engine was no longer producing power, but the propeller was windmilling. The pilot elected to leave the landing gear retracted and set up a glide approach tracking to the north-east to locate a more suitable landing area to conduct a forced landing. A suitable paddock was identified that was near a house. The aircraft flew over a line of tall trees and then clipped a fence that was next to a private road leading to the house, went through and was partially arrested by a second fence on the other side of the road, impacted a large log and came to rest. A passer-by assisted the pilot evacuate the aircraft. The pilot was seriously injured and transported to hospital and the aircraft was substantially damaged.

This accident is a timely reminder for pilots to consider the effect an in-flight engine failure at different altitudes has on the time available to manage that failure and identify a suitable forced landing area.

Aviation Short Investigations Bulletin - Issue 38

What happened

At about 1324 Eastern Standard Time on 28 July 2014, the flight crew of an Airbus A320 aircraft, registered VH-VFU, was preparing the aircraft for the return leg from Sydney, New South Wales, to Adelaide, South Australia.

ATC issued the crew with a departure clearance for runway 16L. A Configuration 2 (flap and slat setting) was required for take-off. Shortly after, ATC advised the crew that the clearance was cancelled and re-issued a new departure clearance for runway 34L.

As a Configuration 1 + F would now be required for take-off, the FMGC was updated. The crew then briefed on the new departure, however neither crew member recalled specifically briefing on the changed take-off configuration.

The PM inadvertently selected the originally calculated Flap 2 take-off setting. He then checked the flap position on the upper ECAM. As he believed he needed to set flap 2, the flap 2 setting displayed on the ECAM confirmed what he believed to be correct.

Despite carrying out all the required flows and checklists, as they taxied the aircraft to the runway 34L holding point, neither of the crew detected the incorrect configuration setting. The aircraft departed normally, and at about 800 ft the crew detected and managed the error and continued to Adelaide.

Jetstar has advised the ATSB they are taking the following Safety Actions.

Jetstar has decided to undertake a detailed review of the results from their Flight Safety Integration Audit (FSIA) program. This is a continuous safety audit program targeted toward identifying specific operational threats and risks associated with failed/erroneous Human-Machine Interface activities. The airline will then develop action plans to address any identified themes.

Jetstar will also incorporate a summary of the incident in the next edition of the company flight crew Technical Newsletter. This will include suggestions on how to mitigate against similar occurrences.

Aviation Short Investigations Bulletin - Issue 39

What happened

On 26 July 2014, the crew of a QantasLink Boeing 717 aircraft, registered VH-NXL (NXL), conducted a scheduled passenger flight from Karratha to Perth, Western Australia, where runways 21 and 24 were in use. At about 1200, the first officer of NXL contacted the aerodrome controller (ADC) who acknowledged the call. At about 1201, an airport safety officer contacted the ADC and advised that their vehicle was holding short of runway 24 for a runway inspection. The ADC cleared the vehicle to enter runway 24 and hold short of runway 21, then indicated on the console runway strip that runway 24 was occupied.

At that time, NXL was on final approach about 7.5 NM from runway 24 and the flight crew did not hear the vehicle being cleared onto the runway. The safety officer drove along the centreline of runway 24 towards the intersection with runway 21.

At about 1203, the ADC cleared an aircraft for take-off from runway 21. After observing that aircraft pass through the intersection of runway 24, the ADC picked up the flight progress strip for NXL, scanned the runway but did not see the vehicle on it, and moved the strip into the console runway bay. The ADC then cleared NXL to land on runway 24. At that time, NXL was on final at about 1,000 ft and 1.5 NM from the runway threshold. The safety vehicle was on runway 24 heading south-west. The safety officer heard NXL being cleared to land but not the assigned runway.

As NXL touched down on runway 24, the first officer saw the flashing lights of a vehicle ahead on the runway, immediately stated ‘go-around, car on the runway’ and the captain commenced a go-around. The safety vehicle was then stationary on the centreline of runway 24 about 1180 m from the threshold and facing away from the approaching aircraft. The safety officer did not see the aircraft until it passed about 150 ft over the safety vehicle.

With experience comes the ability to fuse conscious control with largely automated actions. The penalty for this can be absent-mindedness or a lack of attention to a specific task.

Aviation Short Investigations Bulletin - Issue 39

On 23 May 2014, a Qantas Airbus A380 aircraft, registered VH-OQK, was operating a scheduled passenger service from Los Angeles, USA to Melbourne, Australia.  While overflying Hawaii, USA, the battery within a passenger’s personal air purifier (worn around their neck on a lanyard) began to overheat and produce smoke. The crew followed documented emergency procedures and immersed the device in water; effectively dissipating the heat from the battery and suppressing any further smoke evolution. The passenger received minor superficial burns which did not require first aid treatment.

A preliminary investigation conducted by the ATSB identified that the device contained a small non-rechargeable lithium battery; the size of which conformed with the limitations specified for carry-on items. The Bureau also found that the crew acted in an appropriate manner to manage the overheating battery and control the associated risks.

Given that the ATSB’s records show that this type of battery failure is quite uncommon and both the crew’s actions and documented procedures were effective in managing the small risks involved, there would be limited safety benefit in investigating the matter further, and as such, the ATSB investigation has been discontinued.

The ATSB continues to monitor and record incidents involving lithium batteries and reminds passengers to consult the dangerous goods brochure published by the Civil Aviation Safety Authority when bringing devices containing lithium batteries aboard aircraft.

Safety summary

What happened

At about 0800 on 26 July 2014, Genesee & Wyoming Australia (GWA) freight train 6DA2 derailed at the 1036.541 km mark near Marryat, South Australia.

The train was travelling at about 80 km/h when it derailed. The trailing locomotive, crew van and 17 wagons derailed, with the train separating into two portions that came to a stand about 108 m apart. The wagons (consisting of 35 platforms) and 340 m of track were significantly damaged.

There were no injuries sustained by the driving train crew or drivers resting in the derailed crew van.

What the ATSB found

The ATSB found the train had derailed on a section of 80 lb/yd rail, while travelling over a flash-butt welded joint that had fractured through a pre-existing defect in the rail foot. The defect most likely occurred during the flash-butt welding process, which subsequently led to crack propagation and brittle fracture that extended vertically through the rail web.

Metallurgical evidence indicated that the fracture had propagated slowly from the initiating defect and had likely been in existence for some time, remaining undetected during track inspections and the passage of trains for a period up to 30 years.

Due to the 80 lb/yd rail’s age, smaller section size and surface condition, all trains travelling those sections of track were speed restricted to 80km/h. While the rail through the area of the derailment had been subject to periodic visual and non-destructive inspections across its lifetime, it was evident that the inspection regime had not been effective in detecting and/or assessing some internal rail defects. Several of those defects had the potential to pose an immediate threat to the safety of rail services.

What's been done as a result

Following the derailment, the track manager (GWA) immediately slowed train speed over 80 lb/yd rail to 40 km/h for passenger trains and 50 km/h for freight trains. GWA then carried out a detailed continuous ultrasonic ‘cleansing test’ of the 80 lb/yd rail between Northgate and Alice Springs. To increase the sensitivity of the inspection, the ultrasonic intensity was increased by 6 dB and the test vehicle operating speed was slowed to between 10-12 km/h.

This inspection detected another broken rail at a flash-butt weld at the 975.244 km mark. This fracture had also initiated from the rail foot and required immediate plating and repair. Another 31 rail defects were found requiring various levels of response.

GWA advised that the continuous ultrasonic inspection frequency of 80 lb/yd rail has been increased to a minimum of four inspections per year and a programme to replace all 80 lb/yd rail is being evaluated.

Safety message

Railway owners and managers should ensure that their inspection and maintenance processes, for sections of rail that have a high incidence of defects, are an appropriate and effective management strategy for mitigating the risk of failure under the passage of a train.

The occurrence

At about 0800^[1] on 26 July 2014, Genesee & Wyoming Australia (GWA) freight train 6DA2 changed operating crew near Hugh River, Northern Territory. The train then continued its journey south before crossing the Northern Territory – South Australia border. At about the 1056 km mark^[2] the train entered a section of track that had a permanent speed restriction of 80 km/h, due to a known history of more frequent defects being encountered during inspection.

Figure 1: Map of derailment location

Source: FreightLink (annotated by ATSB)

The crew reported that train had been handling well when the driver reduced the speed with throttle and dynamic brake applications to enter the 80 km/h section (Figure 1). At about the 1036.541 km mark, the driver had just acknowledged the vigilance indication and was verifying the train’s speed when the crew heard two ‘large bangs’ and felt the lead locomotive jar. The crew, aware that the ‘bangs’ may have been the locomotive bogies passing over a break in the rail, looked in the rear view mirrors and could see large volumes of dust rising from derailed wagons and displaced containers about 200 m behind the driver’s cab. At this time, the locomotives started shuddering; after which the driver made an emergency brake application and moved the throttle back to idle. The lead locomotive stopped about 360 m from the point of derailment.

Events after the derailment

Neither of the drivers was injured as a result of the derailment. The second driver alighted from the locomotive to check on the crew resting in the crew van, confirming that they were also uninjured. When walking back to the crew van, the second driver observed that the wheelsets of the leading bogie on the trailing locomotive and the wheelsets of the trailing bogie on the crew van had also derailed.

Further inspection of the train found that it had separated into two sections, with the locomotives, locomotive refuelling wagon, crew van and one loaded container flat wagon remaining coupled. There was a gap of about 108 m between the front section of train and the first of the derailed wagons. Seventeen rail vehicles consisting of 35 platforms, freight and containers were scattered either laterally or vertically for about 250 m along the rail corridor (Figure 2). The rear 930 m of the train, extending north beyond the point of derailment, remained on-rail.

The rail vehicles and about 340 m of track infrastructure had sustained significant damage.

Figure 2: Derailed wagon and wreckage about 100m from the point of derailment

__________

1. The 24-hour clock is used in this report and is referenced from Central Standard Time (CST), UTC + 9.5 hours.
2. Distance in kilometres from the reference point located at Coonamia, South Australia.

Context

The location

The derailment occurred near Marryat (1036.541 km) on the Tarcoola to Darwin railway, about 28 km south of the Northern Territory - South Australia border (Figure 1).

Train and train crew information

Train 6DA2 was a freight service operated by GWA between Darwin and Adelaide. The train consisted of two locomotives (GWU 006 leading and ALF 23 trailing), hauling an in-line fuel wagon, a crew van and 42 freight wagons (including 14 multi-platform wagons). The train was 1543.3 m long and had a trailing mass of 2540.9 t.

At about 0920 on 25 July with a crew of four drivers, train 6DA2 departed from the Berrimah Freight Terminal, Northern Territory. The drivers worked the train in pairs, operating in rotating relay shifts. The drivers operating the train at the time of derailment had about 2.5 and 7 years rail industry experience respectively.

Preliminary examination of on-board recorded data found no evidence of anomalies with the train handling or mechanical condition before the derailment. A review of video and audio recordings extracted from leading locomotive GWU 006 supported the drivers’ report of a ‘large bang’ when they travelled over what they thought was a broken rail (Figure 3).

Figure 3: Location of rail defect & minor ballast displacement near 1036.541 km mark

Source: Genesee & Wyoming – Locomotive GWU 006 video camera

Environmental conditions

The Bureau of Meteorology weather stations nearest the derailment were located at Kulgera (47 km NNW) and Ernabella (120 km E). Daily weather measurements of temperature, humidity, wind and rain at Kulgera were taken twice per day at 0900 and 1500. At Ernabella measurements were more regular and reported at half hourly intervals.

Temperatures recorded at Kulgera and Ernabella on 26 July at 0900 (near the time of the derailment) were 10.4 C and 10.3 C respectively. At Ernabella, a low of 0.9 C was recorded at 0600, with temperatures at 0300 and 0800 recorded as 2.4 C and 2.9 C respectively. It is likely that temperatures at Kulgera would have been similar at these times.

No rainfall was recorded and winds were light; generally from a northerly direction.

Track information

The track infrastructure was owned and maintained by GWA, with the movement of rail traffic controlled from GWA’s Transport Control Centre located at Dry Creek in South Australia.

The standard gauge (1435 mm) track at the derailment location consisted of 80 lb/yd rail fastened to concrete sleepers by resilient clips. The track formation comprised sand/clay based soil, topped with a capping layer and overlaid with ballast to a nominal design depth of 250 mm. The track bed supported prestressed concrete sleepers spaced at 667 mm centres.

Approaching the derailment site from Kulgera, the track was tangent^[3] and the terrain slightly undulating. The derailment occurred within a 68 km section of track where the maximum speed was restricted to 80 km/h, due to the age, smaller section size and surface condition of the 80 lb/yd rail.

Rail examination

The ATSB examined the track leading into the derailment site and determined the most likely contributor was a break in the east rail near the 1036.541 km mark. It was evident that the rail had fractured at a point where two lengths of rail had been flash-butt welded^[4]. An inspection of the mating ends from two broken rail sections strewn near the point of derailment identified variable oxidisation levels across the fracture surfaces and a localised feature that was characteristic of an internal material defect.

The oxidisation that extended across the fracture through the rail foot and web was noticeably heavier and more prominent than that across the rail head fracture surfaces. This was consistent with the fracture developing in a progressive manner - originating in the rail foot and propagating vertically through the rail web.

Evidence of iron oxide bleed on the top surface of the foot suggested that the fracture had propagated slowly and had been in existence for some period of time – potentially remaining undetected during track inspections and the passage of previous trains.

The rail head at the fracture point showed light battering from train wheels that had traversed the break, before the rail breakup extended into multiple other sections - each about 700 mm long.

Analysis of broken rail sections

The ATSB quarantined sections of the broken rail for the purposes of laboratory metallurgical examination and analysis. The Monash University Institute of Railway Technology (IRT) carried out an analysis of four rail sections removed from the derailment site and, for comparison purposes, one section of 80 lb/yd rail from a stockpile at Kulgera, Northern Territory.

The analysis included:

• examination and characterisation of the fracture surfaces
• assessment of the defect initiation and growth behaviour, including contributing factors
• assessment of the rail material for compliance against relevant manufacturing specifications and standards;
• identification of the root cause(s) of the rail failure
• assessment of a flash-butt weld in a rail section removed from the Kulgera stockpile.

The 80 lb/yd rail that failed at the derailment site was manufactured for the Commonwealth of Australia in 1916, most likely at the BHP, Newcastle steel mills. The track section had been constructed between 1975 and 1980 from a combination of used (reclaimed) rail and unused (stored) rail. The joint was flash-butt welded by the Commonwealth Railways Flash-butt Welding Workshop at Port Augusta, South Australia. The flash-butt welding process was verified through daily sample tensile failure tests and random ultrasonic examination of production welds in the workshop and in the field following track laying.

The IRT examination found that:

The fractured flash-butt weld contained a fusion defect at the bond line in the rail foot. Differences in the surface condition over the remaining regions of the fracture indicated that failure of the weld occurred progressively, commencing with some initial cracking of the region surrounding the weld defect (possibly immediately following the welding process, and while the weld was cooling to ambient temperature).

A second stage of cracking occurred over the remainder of the foot and most of the web at some unknown time prior to the date of the derailment. The final stage of cracking occurred over the remaining uncracked region in the centre of the head. The second and subsequent stages of failure involved brittle fracture.

All subsequent rail failures, i.e. in parent rail material, occurred by brittle fracture as a result of the conditions created by or during the derailment.

Figure 4 illustrates the fusion defect through failed flash-butt weld region. The defect was present below the web of the rail foot and presented as a depression measuring 8 mm wide by 10 mm high. A surrounding darker region measuring 18 mm in diameter was consistent with pre-existing cracking and subsequent crack surface degradation.

Figure 4: Flash-butt weld fusion defect and brittle fractures

Source: ATSB

Metallurgical analysis (by IRT) of the weld heat affected zone suggested that the defect most likely formed as a fusion-line flaw when the joint was flash-butt welded (between 1975 and 1980). Analysis also suggested that the quality of this weld would not meet the specifications of the current Australian Standard, AS 1085.20 - Railway track material - Welding of steel rail. The presence of the fusion defect ultimately led to the failure the flash-butt weld at the bond line. The fracture surface immediately surrounding the weld defect was ‘extensively degraded’ and most likely developed in the immediate post-weld cooling period.

Second-stage cracking was by brittle fracture over the remainder of the foot and most of the web (Figure 4), however the crack growth rate and interval before the derailment of train 6DA2 could not be determined. The IRT reported that the ambient temperature variations^[5], in particular low overnight minimum temperatures, ‘would result in increased longitudinal stresses in continuously welded rail; in turn increasing the risk of rail failure’. A small amount of rain was recorded twice in early July and the levels of humidity would have contributed to the corrosion of the recently formed fracture surfaces.

To assess the quality of the flash-butt welded joints, a random sample of 80 lb/yd rail containing a welded joint was selected as an exemplar from a stockpile at Kulgera. The IRT examination subsequently found a 10 mm defect in the upper weld area of that joint – further raising concerns about the quality of the flash-butt joints in the 80 lb/yd rail. The findings also suggested that before stockpiled rail is used in mainline track, additional detailed manual ultrasonic inspections should be carried out to verify the quality of flash-butt welded joints.

Infrastructure inspections

GWA’s procedures for inspection of track and associated infrastructure are documented in their track maintenance procedure IN-PRC-20 – Inspections, which defines requirements for both scheduled and unscheduled inspections.

The process for scheduled inspections consists of three inspection types:

• Patrol inspections – usually performed while travelling in a road/rail vehicle or while travelling in the cab of a locomotive. Patrol inspections look for obvious abnormal conditions, changes in condition, or evidence of deterioration rates that may indicate unacceptable risk to operations.
• General inspections – usually performed in response to previously identified defects or unusual rail conditions.
• Detailed inspections – examine specific aspects of the infrastructure condition or behaviour and may involve visual inspection, measurements, testing and assessment.

Unscheduled inspections are usually in response to an event (temperature extremes, earth slips, floods, earthquakes) or following reports of a suspected unsafe condition from drivers, other workers or members of the public.

The derailment near Marryat occurred within a section of track laid with 80 lb/yd rail. GWA and former corridor managers^[6] had applied an 80 km/h permanent speed restriction to reduce the impact loading on the rail. GWA conducted patrol inspections at a frequency consistent with procedure IN-PRC-20 – Inspections. In the weeks leading up to the derailment on 26 July 2014, scheduled patrol inspections had not reported any track defects near the point of derailment (PoD).

The last track inspection from a locomotive cab before the derailment was on 3 June 2014, where the only defects reported were two track signage issues. Other inspections of this type carried out on 23 July 2013, 20 December 2013 and 25 March 2014 identified various items including rough riding, mud-hole, ballasting and some dip welds^[7]. No defects indicating or suggesting rail or track deficiencies were reported through locomotive cabin inspections in the vicinity of the PoD.

GWA records showed that track at the1036.541 km mark had been tamped^[8] in September 2013 with a detailed track geometry inspection carried out shortly after (October 2013). About four months later, in February 2014, another detailed track geometry inspection was carried out. No track defects were recorded at or near the PoD.

Ultrasonic inspection

In the context of this investigation, it was evident that a weld fusion defect was present in the foot of the rail, which subsequently led to crack propagation and brittle fracture. Such defects within the rail cannot usually be detected through visual inspection (patrol and locomotive cab inspections) unless the defect subsequently causes a secondary defect such as a broken rail or dip weld. Consequently, detailed ultrasonic inspections are conducted periodically to detect internal rail defects.

Ultrasonic rail testing involves passing sound waves into the rail and monitoring the echo returned by the sound waves reflecting off internal and external surfaces (reflectors). Defects within the rail create reflectors which may return unique echo patterns depending on their type, location and size. Examination of the echo patterns allows an operator to deduce the existence, type and size of suspected rail defects.

A series of ultrasonic probes on the ultrasonic test vehicle are located near the surfaces of both rails, while the electronics are mounted inside the vehicle. A computer monitor is provided in the vehicle cabin to allow the operator to monitor and assess information transmitted from the ultrasonic test equipment.

Ultrasonic probes of differing sound beam angles scan each rail, where:

• A 0-degree probe scans the central part of the railhead, the whole of the rail web and the central part of the rail foot perpendicular to the rail.
• Forward and reverse 37-degree probes scan the central part of the railhead, the whole of the web and the central part of the rail foot.
• Forward and reverse 70-degree probes scan the railhead and part of the upper web.

Portable hand operated ultrasonic equipment is used for manually verifying:

• suspected defects recorded by the continuous ultrasonic inspection process
• suspected defects found by visual inspection
• known defects requiring re-inspection and reassessment
• the integrity of new flash-butt and aluminothermic rail welds.

GWA procedure IN-PRC-20 specified that vehicle-mounted continuous ultrasonic testing of rail should be carried out at a minimum of 12-monthly intervals. In November 2013 (about 8 months before the derailment of train 6DA2), continuous ultrasonic testing was carried out by Speno Rail Maintenance Australia Pty Ltd (Speno), between Northgate, South Australia and Alice Springs, Northern Territory. That inspection found four vertical split head^[9] defects over 82.6 km of 80 lb/yd rail. These defects ranged from 200 mm to 600 mm long and were removed. The inspection did not reveal any reportable weld fracture defects near the PoD.

Response to track defects

GWA procedure IN-PRC-010 - Maintenance Standards for Maintenance Procedures defines the standards and tolerances to be adopted when performing maintenance to ensure the condition of infrastructure remains within limits that are compatible with operating requirements. Defects in the foot of welds are managed in accordance with the size limitations specified in Table 1.

Table 1: Defects detected in the foot of existing welds

Transverse and vertical flaws in the rail foot are difficult to identify due to the narrow web area when using 37 and 70 degree probes. A 90 degree probe (longitudinal to the rail) is ideal for the detection of flaws in the rail foot, however use of this probe is not practical for continuous ultrasonic testing of in-situ rail.

Post-derailment re-examination of the November 2013 ultrasonic test results found an anomaly in the rail foot of a flash-butt weld near the 1036.541 km mark. The anomaly had not activated a defect exceedance alarm and was not noted by the test operator. Subsequent manual assessment of the anomaly suggested the existence of a defect measuring between 9 and18 mm in diameter. Speno advised that a defect of 9.0 mm (or greater) would normally produce a defect alarm, thereby prompting a manual ultrasonic test of the suspected defect. In this case an alarm had not been generated, suggesting that the automatic system assessed the defect as falling below the defined alarm limit.

Following the derailment of 6DA2, GWA implemented immediate risk mitigation strategies by limiting the speed of freight trains to 50 km/h and passenger trains to 40 km/h. These speed restrictions remained in place until all 80 lb/yd flash-butt and aluminothermic welds had been assessed as free of defects. Additionally, track patrol inspections on the 80 lb/yd sections were increased to six times per week, and included an inspection ahead of all passenger train services. Detailed ultrasonic testing frequency was increased from annual to 3-monthly tests for rail south of Alice Springs and 6-monthly north of Alice Springs.

Rail defect growth rate

Factors that influence the growth rate of defects in rail include:

• quality and age of the rail
• residual stresses
• on-site temperature differentials
• track curvature
• axle load
• dynamic train forces due to speed
• cumulative train tonnage over the track.

Of these, the influence of cumulative train tonnage on track integrity is well documented in technical studies/papers and had been factored into GWA’s inspection intervals for continuous ultrasonic inspection. The track infrastructure manager can readily monitor cumulative train tonnage and the history of track defects. Inspection strategies can be adjusted to mitigate the risk of track failure based on this information.

In determining whether there is justification in increasing the frequency of inspection, GWA procedure IN-PRC-10, Construction, Monitoring & Maintenance Standards for Maintenance Procedures, does not address factors such as rail quality/age, on-site temperature and issues such as wagon impact loading. Research indicates that defect growth from initiation to 10 percent of its final (critical) size is relatively slow, but then accelerates quite rapidly through to failure. As a rail defect grows, the chance of detecting it increases, however the internal stress levels also increase - raising the risk of a rail failure. Increasing the frequency of continuous ultrasonic inspection may thus assist in capturing a greater number of defects earlier in their growth phase - before they reach critical size and result in a catastrophic failure.

GWA were aware of the increased risk of defects within the sections of track laid with 80 lb/yd rail and had responded to this by increasing the number of patrol inspections (defined in IN-PRC-020). These inspections increased from one to two or more per week. Inspection effort was also intensified, particularly during winter and spring, where low temperatures increases rail tensile forces that can result in rail breaks. The last continuous ultrasonic inspection before the derailment was carried out in November 2013, about 8 months before the derailment on 26 July 2014. No weld cracks or internal defects were found at this time.

__________

3. Straight track with no applied cant.
4. The fusion welding of rail ends by electric arc heating and contact under high pressure.
5. Bureau of Meteorology records (Kulgera and Ernabella) for the period 1 – 26 July 2014 (derailment of 6DA2)
6. Australian National, the Australian Rail Track Corporation and FreightLink
7. A downward variation in the running surface of a rail as may occur at welds or rail ends.
8. Tamping is the process by which ballast is packed around the sleepers of a track to ensure the correct alignment for the location, speed and curvature of the line.
9. An internal vertical seam in the railhead splitting out onto the top of the rail.

Safety analysis

On 26 July 2014, GWA freight train 6DA2 derailed at the 1036.541 km mark, near Marryat, South Australia. An examination of the rail at that location determined the most likely contributor to the derailment was a fracture extending through a flash-butt welded joint within the east rail. The fracture had commenced from an internal defect in the rail foot and had propagated vertically towards the rail head.

Detection of rail defects

Following the derailment of train 6DA2, a detailed continuous ultrasonic ‘cleansing test’ of the 80 lb/yd rail between Northgate and Alice Springs commenced on 3 August 2014. To increase the sensitivity of the inspection process, the ultrasonic intensity was raised by 6 dB and the test vehicle operating speed was slowed to 10-12 km/h.

This inspection revealed 31 potential defects, compared to only nine such defects found during the inspection in November 2013. Of these defects, 15 were below the limits requiring any action and 12 required monitoring for deterioration into the future. All defects were within the head of the rail except for two which were in the rail web. There were 13 potential defects detected in flash-butt welds and four in aluminothermic welds. The four higher-priority defects (two in flash-butt welds) were subsequently repaired, including another broken rail at the 975.244 km mark, which had also fractured through a flash-butt weld at a defect in the foot area. In accordance with GWA’s procedures, the broken rail was repaired before the passage of the next train.

Two of the defects detected in the ‘cleansing test’ had also been detected in November 2013, but at that time both were classified as small, low priority and logged for monitoring. The more detailed ultrasonic inspection (August 2014) subsequently rediscovered these defects and assessed them as requiring more frequent monitoring and reassessment until the defects were removed. Having found these higher-priority defects, including a defect similar to that which precipitated the derailment, GWA immediately implemented a 20 km/h temporary speed restriction (TSR) for traffic on all 80 lb/yd rail until all ultrasonic testing was completed.

It was evident that the ultrasonic ‘cleansing test’ of 3 August 2014 was more effective than the inspection carried out in November 2013 for the detection of all classes of defects. Given the extended timeframes over which typical rail foot defects develop, it was likely that growth of the flaws identified at 1036.541 km (the PoD) and 975.244 km was well advanced at the time of the November 2013 inspection. On this basis therefore, it was evident that the ultrasonic testing conducted in November 2013, as part of GWA’s scheduled maintenance processes, had been inefficient at detecting and/or appropriately assessing some internal rail defects in the 80 lb/yd rail between Northgate and Alice Springs.

Special locations

On the Tarcoola to Darwin railway there was a total of 82.6 km of 80 lb/yd rail laid in two locations^[10] – including through the derailment site near Marryat. Due to the rail age, smaller section size and surface condition, GWA advised that they managed these sections as special locations, where the 80 km/h permanent speed restriction has been maintained for more than 10 years.

The RISSB^[11] Code of Practice for the Defined Interstate Network Volume 4 – Track, Civil and Electrical Infrastructure - Part 1: Infrastructure Management (CoP), describes the term ‘special location’ and states:

Common management practice used by railway managers is to identify certain locations of the infrastructure that exhibit a history of proneness to an event (environmental or other conditions) that may cause the location to have a higher risk of failure. In this Code these locations are called “special locations” and the event(s) that cause each “special location” to be at a higher risk are called the “defined event(s)”. The conditions at “special locations” cannot in general be adequately ascertained through normal scheduled inspections and require additional actions to be taken when the defined event occurs.

Infrastructure affected by defined events described in the Code may be managed as special locations and includes, but is not limited to, infrastructure prone to flooding, earthworks instability and track lateral instability.

Typically, infrastructure locations with a higher rate of deterioration or recurring anomalies are identified and classified as special locations. Where special locations have been identified, the recording and management of risks to train operations should be carried out to manage those risks.

GWA procedure IN-PRC-020 specifies that all defects found through patrol, general and detailed inspections are documented and recorded in the Rail Maintenance Management System (RMMS).

In accordance with IN-PRC-020, GWA’s treatment of track sections affected by previously defined events and identified as a higher risk can be assessed and managed as special locations.

For special locations, GWA track inspectors are required to:

• ‘look for obvious abnormal conditions that may impair the capability of the infrastructure during defined events’ and,
• ‘use a list of specific locations requiring particular attention during inspections’.

During the investigation, GWA advised that the organisation relied on ‘the local knowledge of track inspectors and other track and infrastructure staff to identify locations which may affect network integrity under certain conditions e.g. during periods of high ambient temperatures’.

Contrary to the requirements for special locations, GWA was unable to provide records identifying locations where additional (special) measures had been implemented to manage track areas known to have an increased likelihood of failure. Where this historical information is not recorded, there is limited opportunity to gauge the effectiveness of infrastructure management regimes or the risk levels associated with continued operations.

Reliance on local knowledge of staff, and not maintaining specific records documenting known areas of elevated risk may have reduced the effectiveness of GWA’s inspection and maintenance task. Consequently, there was an increased likelihood of an infrastructure failure and a direct impact on railway safety

__________

10. Between 965.7 to 981 km (15.3km) and between 988.7 to 1056km (67.3km)
11. RISSB – Rail Industry Safety & Standards Board

Findings

From the evidence available, the following findings are made with respect to the derailment of train 6DA2 near Marryat, South Australia on 26 July 2014.These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Safety issues, or system problems, are highlighted in bold to emphasise their importance. A safety issue is an event or condition that increases safety risk and (a) can reasonably be regarded as having the potential to adversely affect the safety of future operations, and (b) is a characteristic of an organisation or a system, rather than a characteristic of a specific individual, or characteristic of an operating environment at a specific point in time.

Contributing factors

• A rail fracture originating from the foot of a defective flash-butt welded joint initiated the derailment of train 6DA2 near Marryat, SA on 26 July 2014.
• The scheduled ultrasonic tests conducted in November 2013 on the 80 lb/yd rail between Northgate and Alice Springs had been ineffective in detecting and quantifying the significant defects present at 1036.541 km and 975.244 km locations. [Safety issue]

Other factors that increased risk

• Contrary to the requirements of procedure IN-PRC-020, GWA had not established a list of specific locations known to have an increased likelihood of failure, such that particular attention may be applied in those locations during inspections. [Safety issue]

Other findings

• There were no identified mechanical defects or deficiencies with the locomotives and trailing vehicles.
• Train handling and speed were not considered factors in the derailment.
• Although visual patrol inspections were carried out regularly, the nature of the developing defect was such that it was unlikely that more frequent inspections of this type would have discovered the defect or the fractured rail before the passage of train 6DA2 and its subsequent derailment.

Safety issues and actions

The safety issues identified during this investigation are listed in the Findings and Safety issues and actions sections of this report. The Australian Transport Safety Bureau (ATSB) expects that all safety issues identified by the investigation should be addressed by the relevant organisation(s). In addressing those issues, the ATSB prefers to encourage relevant organisation(s) to proactively initiate safety action, rather than to issue formal safety recommendations or safety advisory notices.

All of the directly involved parties were provided with a draft report and invited to provide submissions. As part of that process, each organisation was asked to communicate what safety actions, if any, they had carried out or were planning to carry out in relation to each safety issue relevant to their organisation.

The initial public version of these safety issues and actions are repeated separately on the ATSB website to facilitate monitoring by interested parties. Where relevant the safety issues and actions will be updated on the ATSB website as information comes to hand.

Detection of rail defects

The scheduled ultrasonic tests conducted in November 2013 on the 80 lb/yd rail between Northgate and Alice Springs had been ineffective in detecting and quantifying the significant defects present at 1036.541 km and 975.244 km locations.

Safety issue number: RO-2014-014-SI-01

Special locations

Contrary to the requirements of procedure IN-PRC-020, GWA had not established a list of specific locations known to have an increased likelihood of failure, such that particular attention may be applied in those locations during inspections.

Safety issue number: RO-2014-014-SI-02

Sources and submissions

Sources of information

The sources of information during the investigation included:

Genesee & Wyoming Australia

The drivers and crew of train 6DA2

References

Australian Standard, AS 1085.20-2012 - Railway track material - Welding of steel rail

Australian Standard, AS 4292 Railway Safety Management Part 1 General Requirements - 6.2 Process Control (b), (f)

Bureau of Meteorology – Weather Observations, Ernabella/Pukatja (Station ID 16097)

Bureau of Meteorology – Weather Observations, Kulgera (Station ID 15603)

Code of Practice for the Defined Interstate Network Volume 4 – Track, Civil and Electrical Infrastructure - Part 1: Infrastructure Management

Genesee & Wyoming Australia - Construction, Monitoring & Maintenance Standards for Maintenance Procedures - IN-PRC-10

Genesee & Wyoming Australia - Infrastructure Procedure – Inspections – IN-PRC-020

RISSB Glossary of Railway Terminology - Guideline

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to Genesee and Wyoming Australia, the drivers and resting crew of train 6DA2, and the Office of the National Rail Safety Regulator.

Submissions were received from all parties. These were reviewed and where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

What happened

On the morning of 18 July 2014, a Boeing 777 operated by Emirates Airlines, registered A6-ECO, was on descent into Melbourne, Victoria via an ARBEY 4U Standard Arrival Route (STAR)^[1] for the Area Navigation U (RNAV-U) Required Navigation Performance (RNP) runway 16 approach. There was some cloud and showers in the area at the time, with the wind from the south-west.

The ARBEY 4U STAR required that the aircraft track from ARBEY to BUNKY, then to the Bolinda (BOL) non-directional (radio) beacon (NDB).^[2] The arrival procedure included speed and altitude restrictions at BUNKY, and a speed restriction at BOL, but there was no altitude restriction at BOL depicted on the STAR chart. Even though there was no altitude restriction depicted at BOL, the STAR chart depicted a minimum en route altitude (MEA) of 3,400 ft and a minimum terrain clearance altitude (MTCA) of 3,700 ft, between BUNKY and BOL (Figure 1).^[3]

Figure 1: Excerpt from the ARBEY 4 STAR chart used by the operator depicting MEA (3400) and MTCA (3700)

Source: Aircraft operator – image cropped by the ATSB

The ARBEY 4U STAR linked to the RNAV-U (RNP) runway 16 approach at BOL, which was identified as the initial approach fix for the RNAV-U (RNP) runway 16 approach. While no altitude was specified at BOL on the STAR chart, the RNAV-U (RNP) runway 16 approach chart depicted two altitudes at BOL (Figure 2). These were:

• an ‘at or above’ 4,000 ft altitude restriction at BOL when joining the approach from the ARBEY STAR
• an ‘at or above’ 3,000 ft altitude restriction at BOL applicable when the approach was linked with STAR procedures other than the ARBEY STAR.

Figure 2: Excerpt from the RNAV-U (RNP) runway 16 approach chart used by the operator depicting two altitudes at BOL

Source: Aircraft operator – image cropped by the ATSB

As the aircraft approached BUNKY, air traffic control (ATC) cleared the crew to descend to 4,000 ft, and to conduct the RNAV-U (RNP) runway 16 approach. ATC radar data shows that the aircraft overflew BUNKY at 5,000 ft, then continued descent, passing through 4,000 ft about 5 NM prior to BOL. During the approach setup, the Flight Management Computer (FMC)^[4] indicated an altitude constraint for BOL of ‘at or above 3,000 ft’. The crew then selected this to an ‘at 3,000 ft’ constraint, which programmed the aircraft to overfly BOL at a ‘hard altitude’ of 3,000 ft.

Descent then continued, and ATC received a Minimum Safe Altitude Warning (MSAW)^[5] alert, as the aircraft descended through 3,400 ft about 4 NM prior to BOL (Figure 3). ATC questioned the crew about their altitude, and advised them that the relevant radar lowest safe altitude was 3,200 ft. Moments later, the aircraft passed over BOL at about 3,000 ft and maintained that altitude until intercepting the vertical profile of the RNAV-U (RNP) runway 16 approach. ATC then transferred the crew to the next frequency, and the crew confirmed they had the correct QNH setting.^[6] The approach continued for an uneventful landing.

A subsequent review of the ATC radar data showed that the aircraft left controlled airspace as it descended through 3,500 ft. The aircraft was briefly outside controlled airspace until it reached the 15 NM airspace boundary step, where the lower limit of controlled airspace became 2,500 ft. There was no report of conflict with other traffic outside of controlled airspace. Throughout the incident, the crew maintained visual contact with the terrain, and could see the airport environment from some distance out. No aircraft ground proximity warning system alerts were triggered during the incident.

Figure 3: ATC radar image at the time the MSAW alert activated

Source: Airservices Australia (modified by the ATSB)

Review of the factors identified in the investigation

The operator’s investigation found that descent below the 4,000 ft altitude restriction at BOL occurred because the crew selected the ‘hard altitude’ of 3,000 ft for BOL. The potential for deviation below the 4,000 ft minimum altitude restriction at BOL was increased by factors related to aeronautical charts and the FMC navigation database. Some of these factors are discussed in the following paragraphs.

The ATSB obtained comments and responses from involved parties including:

• the United Arab Emirates General Civil Aviation Authority on behalf of Emirates Airlines
• Airservices Australia
• the Civil Aviation Safety Authority (CASA).

The RNP approach had been designed by GE Naverus (Naverus), based on information in the Airservices Australia Aeronautical Information Package (AIP). The charts and FMC data used by Emirates were supplied by LIDO. LIDO developed the charts and database based on information in the Airservices AIP.

Procedure design – level depiction on the ARBEY STAR

No minimum altitude was specified at BOL on the ARBEY FOUR STAR.

Operator comments

Within the STAR, BOL had a coded speed restriction of a maximum 185 kt for approaches to runway 16, but did not specify a minimum crossing altitude. This allowed arrivals from other directions to cross BOL at a minimum altitude of 3,000 ft, instead of 4,000 ft as required via ARBEY. This conditional altitude restriction was specified in the approach charts only and not on the STAR chart. This procedure design did not protect the MEA of 3,400 ft on the arrival segment from position BUNKY to position BOL by a 'hard procedural altitude'. BOL is located at a distance of 11.6 NM from runway 16 and a crossing altitude of 4,000 ft would permit a constant approach angle crossing BOL on a 3.0° vertical descent path. Based on this, a lower crossing altitude (3,000 ft) for other arrival directions does not seem necessary.

The operator suggested that Airservices Australia consider procedural amendments to specify a minimum crossing altitude over BOL (of 4,000 ft or above) for all approaches and within the STAR design. This would protect against descents below MEA (and outside controlled airspace) within the arrival segment from BUNKY to BOL. It would also satisfy the requirement of Airservices Australia to be able to specify higher crossing altitudes (above 4,000 ft) for traffic separation. If Airservices Australia, as the State AIP, changed the procedure design, the various chart providers would then amend their corresponding FMC/FMS databases as well as the STAR and instrument approach charts.

CASA comments

CASA suggested a possible solution would be to include the altitude restriction in the STAR chart. This would then make the altitude obvious on the text and plan view, and the altitude restriction would be coded in the FMS. They also found that the overall complexity of the STAR chart did not aid pilots’ awareness.

Airservices response

In controlled airspace, the approach procedures are designed to keep aircraft 500 ft above the control area steps. The 4,000 ft minimum altitude was designed to keep aircraft in controlled airspace prior to BOL, rather than for terrain clearance.

Airservices further commented that a minimum altitude of 4,000 ft was not depicted on the STAR chart at BOL, as BOL was also applicable to the runway 27 arrival. This allows ATC to assign a higher altitude at that point for a runway 27 arrival due to potential runway 34 departures. No altitudes are depicted because two (or more) levels would be required to cater for the different runways. Only one level is permitted to be depicted against a waypoint (for a STAR) to avoid potential confusion as per Section 1-1-22 of Airservices 'Departure, Arrival and Air Route Management Design Rules' manual (ATS-MAN-0010).

Altitude requirements are not always specified on a STAR chart, and ATC is generally responsible for deciding whether altitudes are to be included or not. This occurs in the procedure design phase. When they are not included on the chart, ATC assigns individual altitudes to aircraft in order to facilitate vertical separation between them and assure terrain clearance.

RNAV-(U) RNP runway 16 approach chart design

Approaches with multiple altitudes at a common fix

Airservices withdrew the RNAV-U (RNP) runway 16 approach early in 2015. Its withdrawal was not related to this incident. The ATSB reviewed all Australian approach charts published in the AIP Departure and Approach Procedures (DAP) current at the time of writing. The approach charts with a discrepancy between the STAR minimum segment altitude and the approach start altitude were Melbourne approach charts ILS – X, Y and Z runway 16, RNAV Z (GNSS) runways 16 and 27. No other Australian approach charts existed with that condition.

Chart depiction of the altitude restriction at BOL – operator comments

The operator reported that the absence of altitude restriction information on the STAR chart reduced the level of protection against deviation below the BOL minimum altitude restriction. The 4,000 ft altitude restriction at BOL when tracking from ARBEY STAR was physically depicted below the 3,000 ft altitude restriction applicable to other STAR procedures (see Figure 4a). This may also have influenced the crew’s interpretation of the FMC altitude.

The following two figures show a comparison of two presentation options for multiple arrival altitudes. These altitudes are boxed in red.

Figure 4a: RNAV (RNP) approach chart used by the crew

Source: GCAA for chart provider (LIDO) modified by the ATSB

Figure 4b: RNAV (GNSS) Z approach chart

Source: GCAA for chart provider (LIDO) modified by the ATSB

Chart provider comments

The chart provider (LIDO) commented that presentation of information on a chart is normally at the discretion of the chart editor and based on:

• the amount of information which needs to be charted
• the amount of information already on the chart
• the space available for the information, based on standard font sizes.

If the information can be charted clearly using a leader line, this is used (see Figure 4a). As soon as the information exceeds two lines, the preference is usually for the information framed together in a box with a ball note^[7] at the point in question (see Figure 4b).

The chart provider advised that on the RNAV (RNP) chart the higher value (4000) should have been depicted above the lower value (3000). They reiterated that the approach chart (Figure 4a) used in this incident is no longer valid.

RNAV-U (RNP) runway 16 approach chart profile view

The approach chart provided a vertical profile view of the approach, but the view began immediately prior to intermediate fix (IF), waypoint UGARU, which is 4.4 NM beyond BOL (Figure 5a). As such, there was no profile view information on the approach chart for the approach from the initial approach fix (IAF) BOL, to UGARU. Had this information been present in a vertical profile, it may have alerted the crew to the different altitude requirements at BOL, associated with the different STAR procedures.

Figure 5a: Excerpt from the RNAV-U (RNP) runway 16 approach chart used by the operator showing vertical profile information

Source: Aircraft operator

Vertical profile view – operator comments

The operator noted that the profile view of Naverus charts was inconsistent with similar Airservices Australia charts. For example, the RNAV-Z (GNSS) runway 16 approach chart, which was designed by Airservices Australia, provided the important hazard information of the different minimum crossing altitudes over BOL in the profile view (Figure 5b). However, the RNAV-U (RNP) runway 16 approach chart, which was designed by Naverus, depicted these altitudes in the plan view only. The operator considered that extension of the profile view, as published on similar Airservices Australia charts, would assist flight crews to select the correct altitude for the IAF.

Figure 5b: Excerpt from the Airservices RNAV-Z (GNSS) runway 16 approach chart for comparison

Source: Airservices Australia

The operator suggested that the profile view of the Naverus charts should be amended to conform to that of the Airservices Australia charts.

Airservices response

Airservices advised that the standard for the approach profile view was to commence at the final approach fix (FAF), and not to include the initial approach fix (IAF). Airservices opted to trial the inclusion of the IAF, in this case BOL, in the profile view of other similar charts. While its inclusion made the approach altitude clearer, Airservices stated that it was not likely to be adopted as the convention, either generally by Airservices or internationally. Naverus charts conform to the ICAO standard, and therefore the profile view did not commence at the IAF.

FMC navigation data

Consistent with the STAR chart, the ARBEY 4U STAR FMC navigation data did not include an altitude restriction at BOL (Figure 6). FMC navigation data for the RNAV-U (RNP) runway 16 approach included an altitude restriction at BOL, but that altitude restriction was ‘3000A’ (meaning ‘at or above’ 3,000 ft) (Figure 7). The 3,000 ft restriction was applicable to a number of STARs that linked with the RNAV-U (RNP) runway 16 approach. But it was not applicable to the ARBEY STAR which had a 4,000 ft restriction.

Figure 6: ARBEY 4U STAR FMC navigation data

Source: Aircraft operator modified by the ATSB

Figure 7: RNAV-U (RNP) runway 16 approach FMC navigation data

Source: Aircraft operator modified by the ATSB

Compliance with the published procedure on this occasion required the crew to modify the FMC vertical profile at BOL by increasing the ‘at or above’ altitude restriction from 3,000 ft to 4,000 ft. Any requirement to modify the vertical profile brings about the potential to introduce errors, the consequences of which may be more significant when the FMC default altitude needs to be increased. If an error is introduced when the FMC vertical profile is modified, vertical path indications displayed to the crew during the approach may be misleading.

FCOM procedure

At the time of the incident, the FCOM stated that crews could change an FMC IAF ‘at or above’ altitude constraint, to an ‘at’ altitude constraint, using the same altitude. Technically therefore, the crew were unable to change the coded 3000A to the correct 4000A. This ambiguity within the FCOM procedure was raised with the aircraft manufacturer via the fleet technical pilots. At the time of publication, a response from the manufacturer was still pending.

FMC approach altitude

As depicted in Figure 6, there was no altitude on the STAR coded in the FMC, so when the crew selected approach mode, the 3000A appeared as the relevant altitude restriction for BOL. Only one altitude can be selected by the FMC. The ATSB was unable to clarify what coding logic was applied to determine which altitude is selected when two are provided.

The aircraft operator commented that they did not raise this issue with the FMC database provider, as the database coding reflects the AIP procedure design. The aircraft operator considered the conditional altitude over the waypoint BOL to be a procedure design weakness and raised that with Airservices Australia accordingly. The approach is no longer valid, but the operator intends to closely monitor for this issue in any new approaches.

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Aircraft operator

Crew awareness of restrictions on STAR

Soon after the occurrence, the aircraft operator published a company Notice to Airmen (NOTAM) for crew awareness. The NOTAM pointed out that approaches into Melbourne may include altitude restrictions that depend on the particular STAR being flown. The NOTAM also pointed out that some altitude restrictions may be depicted on the approach chart plan view only, and not necessarily on the relevant STAR chart, or the approach chart profile view. The NOTAM advised crews to exercise caution when reviewing STAR and approach procedures to ensure that all applicable altitude restrictions were observed.

Flight crew operations manual

The operator intends to reconsider Flight Crew Operations Manual guidance dealing with the benefits of changing initial approach fix ‘at or above’ altitude restrictions to hard altitudes, and discuss the depiction of altitude restrictions on the relevant charts with the chart provider.

Flight management computer coding

The operator has identified the FMC coding issue as a threat in their Hazard Identification and Risk Assessment statements. All new destinations and also, within the review cycle, existing destinations, will be checked against this threat and corrective action will be taken if applicable.

Airservices and CASA

CASA and Airservices intend to discuss the coding of the FMC at the next international instrument procedures panel, where an ‘integration’ subgroup includes FMC coding specialists. The aim of the discussion is to ensure the charts are used in the cockpit the way they are intended.

Safety message

For operators, this incident highlights the need for careful attention to FMC navigation data management, particularly any procedures that relate to crew modification of navigation data. Operators should remain mindful that any manipulation of FMC navigation data by flight crew has the potential to introduce errors. Additionally, operators are encouraged to work closely with aeronautical information service providers to ensure that aeronautical charts (and any other operational information) are presented in a manner that minimises ambiguity and reduces the potential for misinterpretation.

For flight crew, this incident highlights the need for careful attention to approach procedure documentation and FMC navigation data management.

For producers and providers of aeronautical information products, a guiding principle specified in Procedures for Air Navigation Services, Aircraft Operations is to keep all charts as simple as possible. This may assist in reducing flight crew workload and the risk of error, and coding issues when entering data into flight management systems.

Aviation Short Investigations Bulletin - Issue 43

About this report Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, a limited-scope, fact-gathering investigation was conducted in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.

__________

1. A STAR is a published instrument flight rules arrival route that links the en route airways system to a fix at or near the destination airport.
2. An NDB is a radio transmitter at a known location, used as a navigational aid. The signal transmitted does not include inherent directional information.
3. The minimum en route altitude (MEA) and the minimum terrain clearance altitude (MTCA) are calculated differently, and both are depicted on the STAR chart used by the operator. Only the minimum en route altitude is depicted on the corresponding Airservices Australia STAR chart.
4. The FMC provides aircraft navigation, lateral and vertical guidance, and aircraft performance functions.
5. MSAW is a ground-based system intended to alert ATC to an increased risk of an aircraft collision with terrain.
6. QNH is an altimeter barometric pressure subscale setting. With QNH set, an altimeter provides an indication of the height of the aircraft above mean sea level.
7. The ball note, as depicted in Figure 3b, includes the black circle with reference number 1 at BOL, with the explanation in the box using the same black dot (or ‘ball’) and matching reference number (or letter).

Safety summary

What happened

On 20 July 2014, the pilot of a Cessna 182L aircraft, registered VH-TRS, was conducting a private flight in the local area surrounding the rural township of Burrumbuttock, NSW. The aircraft was observed by witnesses to be travelling at low altitude in a westerly direction toward the township. As the aircraft was flown above a paddock on the outskirts of the town, the aircraft struck wires from a high voltage powerline. The aircraft subsequently rolled inverted and impacted terrain. The wreckage came to rest a short distance from the Farmers Inn. The pilot was fatally injured, and the aircraft was destroyed.

What the ATSB found

The ATSB found no evidence of any engine or airframe defect that may have contributed to the accident. The pilot did not hold any approval to conduct low flying and had not received training in the identification of hazards or in the operating techniques for flight close to the ground. There was no operational reason identified for the pilot to have been flying at such a low altitude on the day of the accident. The evidence also indicated that the pilot had a history of unauthorized low flying.

The pilot was reported to be in good health with no issues that might have affected his ability to fly an aircraft. Despite this, the postmortem medical examination revealed a pre-existing medical condition that could have resulted in pilot incapacitation. While it is possible that the pilot may have had a medical incapacitation event immediately prior to the accident, the aircraft was being operated in a manner consistent with previous flights undertaken by the pilot and at a level that provided little margin for error should such an event have been experienced.

Safety message

This accident highlights the importance to pilots of not flying below the regulated thresholds of 1,000 ft AGL for flight overpopulated areas and 500 ft for flight over non-populated areas. Pilots who fly below this height without appropriate training and an operational reason to do so are exposing themselves and any passengers that may be on board to an increased risk of striking hazards, such as electrical power lines, many of which are difficult to see from the cockpit of an aircraft in flight.

Accident site VH-TRS

Source: ATSB

The occurrence

At about 1700 Eastern Standard Time^[1] on 20 July 2014, a Cessna 182L aircraft, registered VH-TRS, departed from the pilot’s own airstrip for a private flight under visual flight rules^[2]. The pilot was appropriately qualified and endorsed on the type of aircraft. Family members and friends of the pilot reported that he regularly flew on weekends around the Burrumbuttock area. His pilot logbook indicated that the flights were generally short in duration of less than one hour.

About 30 minutes into the flight the aircraft was observed to be flying at a low altitude above the ground in a westerly direction toward Burrumbuttock. At 1733, the aircraft struck two energised electrical wires from a powerline in a paddock that bordered the town. The aircraft continued on for a short distance before it impacted terrain in a steep nose-down inverted attitude, stopping short of the Burrumbuttock ‘Farmers Inn’ hotel (Figure 1).

Patrons within the inn were alerted to the accident and immediately exited the establishment to investigate. A number of people ran to the wreckage to render assistance to the pilot. Despite the presence of leaking fuel, one of the patrons crawled into the aircraft where it was confirmed the pilot had sustained fatal injuries.

Figure 1: The accident site at Burrumbuttock

Source: ATSB

Witness descriptions

There were a number of witnesses identified during the investigation that had either spoken with the pilot early on the day of the accident, who saw the aircraft flying later that afternoon, or who had seen the accident.

Those who saw or heard the aircraft on the day of the accident reported nothing abnormal in its operation. It was noted that it was not unusual to see the aircraft flying quite late in the day around the local area. Two witnesses reported seeing the aircraft flying quite low as it approached the town.

Immediately prior to the accident, the aircraft was observed approaching the town at low altitude. The aircraft appeared to lose height as it banked left, in the direction of the Farmers. It struck the powerlines shortly afterwards. The aircraft subsequently became unstable and impacted terrain a short distance from the hotel.

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1. Eastern Standard Time (EST) was Coordinated Universal Time (UTC) + 10 hours.
2. Visual flight rules (VFR) are a set of regulations that allow a pilot to only operate an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going.

Context

Pilot information

The pilot had lived and worked in the Burrumbuttock region for around 20 years. He had obtained a private pilot aeroplane license in January 1999 and subsequently gained experience in a range of single- and twin-engine aircraft. Toward the end of 1999, the pilot had attained an Aerobatics and Spinning endorsement and in 2005 had also qualified to fly at night under visual meteorological conditions.^[3][4]

The pilot’s logbook showed that he had last undergone and successfully completed a biennial flight review in April 2014. He did not hold a low-level flying endorsement and there was no record of him undergoing low-level flying training. He had accumulated a total of 1,033.6 flying hours, approximately half of which was spent at the controls of the accident aircraft.

The pilot regularly flew the aircraft around the local area and was known to fly over the Farmers Inn, within the Burrumbuttock township, on occasion during weekend flights. A witness to one of these previous flights recalled that the aircraft had passed over the inn, tracking in a westerly direction and that he thought the pilot had maintained a safe altitude.

The pilot occasionally flew with a family friend, also an experienced aviator and one who regarded the accident pilot as someone who flew well and in control. Most of the accident pilot’s flying was around regional New South Wales and Victoria.

Medical and pathological information

The pilot’s last aviation medical assessment was in October 2010, at which time there was no identified medical condition and/or medication which may have affected his ability to operate an aircraft. Family and friends of the pilot reported that he was fit and well rested in the period leading up to the accident.

A post-mortem examination was conducted and the autopsy report stated that the injuries sustained to the pilot were consistent with that of a high energy aircraft accident. Toxicological screening did not reveal the presence of any drugs or toxins.

The autopsy report also stated that narrowing and damage of a major coronary artery to the pilot’s heart was identified. There was an area of plaque haemorrhage and fibrin deposition within the artery that is typically seen as an immediate precursor to a heart attack. The report summarised that, due to abnormalities in the blood vessel, it was possible that the pilot became incapacitated prior to the crash.

Aircraft information

The aircraft was manufactured in the United States in 1968 by the Cessna Aircraft Corporation as a model 182L. The aircraft was a four-seat, single-engine, high-wing configuration with a conventional tricycle undercarriage. The engine fitted was a Teledyne-Continental Motors six-cylinder reciprocating piston variety with a McCauley two-blade, constant speed propeller. The aircraft was certified for visual flight rules (VFR) and VFR Night; where flying during the day or night was permitted under visual meteorological conditions.

The engine fitted to the aircraft had last been overhauled in October 2000. The engine logbooks indicated that it had last been serviced in September 2013, 1,065.5 total hours of engine operation since that last overhaul. All servicing requirements were up to date and the next scheduled service was due on 13 September 2014.

Examination of the daily inspection and service sheet records for the aircraft showed the last complete entry was logged the day before the accident flight at 7,930.8 hours. An incomplete entry on 20 July 2014 indicated that the daily certification inspection had been completed by the pilot. There were no reported problems with the aircraft from family members and persons who were familiar with the aircraft.

Wreckage and impact information

Accident site

A survey of the accident site showed that the aircraft travelled along the flight path for 195 m after contacting the powerlines, before impacting terrain in an inverted, nose-down attitude of approximately 50⁰ - 60⁰. Upon impact with the terrain, the aircraft then slid forward an additional 30 m. These characteristics, in particular, the extended distance travelled from the location of the wire strike, indicated that the aircraft had been travelling with significant forward speed at the time.

Debris along the flight path in advance of the powerline included items from the left wing, comprising a segment of leading-edge skin, plastic pieces from the landing lights and a guide pulley from the aileron controls.

Aircraft structure

The aircraft structure had sustained severe damage from ground impact forces (Figure 2). Both wings were compressed and the tail section had buckled midway along its length. Upon contact with the ground, the nose and front section of the aircraft took the majority of the impact loads, breaking the engine mounts and compromising the survivable cockpit space. The pilot’s seatbelt assembly was locked and secure.

A significant quantity of fuel had leaked from the damaged wing fuel tanks. The front spar from the left wing displayed saw marks and tearing that was consistent with striking the powerline. The marks commenced at the strut-to-spar connection and their general orientation indicated that the aircraft was probably right-wing low at the time of the wire strike (Figure 3).

All of the primary structures and controls were accounted at the accident site. With the exception of the left aileron cable, flight control continuity was established and no pre-impact defects were identified. The left-wing aileron cable had fractured in overstress coincident with the strut-to-front spar connection (Figure 4).

A small sample of fuel was recovered from the fuel sump drain. The colour and smell of the fuel was consistent with aviation gasoline. Testing on-site showed that water was not present in the fuel sample.

Figure 2: The aircraft impacted terrain near the Farmers Inn hotel. The aircraft was inverted at impact and the propeller separated from the engine

Source: ATSB

Figure 3: Illustration showing the likely aircraft orientation at the time of striking the powerline

Source: Illustration by Cessna Aircraft Corporation (modified by ATSB)

Figure 4: The aircraft’s left wing leading edge structure including the aileron guide pulley and cable, was damaged from contact with the powerline

Source: Illustration by Cessna Aircraft Corporation (modified by ATSB); photographs ATSB

Engine and propeller

Analysis of propeller damage can provide evidence of the operational state of an aircraft’s engine at the time of any collision with terrain. In this instance, the engine was severely disrupted during the accident sequence and the propeller had separated from the crankshaft and was embedded in soil a few metres forward of the initial point of ground impact. Both blades from the propeller exhibited chordwise scoring and a degree of bending and twist that was consistent with being operated under significant torque at the time of the accident (Figure 5).

Figure 5: Propeller slash marks (arrowed)

Source: ATSB

Recorded data and instrument examination

Garmin GPS

A severely damaged Garmin AERA 500 GPS navigation unit was recovered from within the wreckage at the accident site. The ATSB applied forensic techniques to remove and then interrogate the internal memory module from the GPS.

Data from the previous 4 months of flying, including the accident flight, was able to be recovered. Parameters recorded by the GPS were: latitude, longitude, altitude and time. Analysis of the data revealed the following:

• The pilot had routinely conducted low-level flying in the local area throughout the previous 4 months, as well as on the day of the accident flight.
• The pilot had flown over the Burrumbuttock ‘Farmers Inn’ on many occasions. On 6 July 2014, 2 weeks prior to the accident, the aircraft was flown over the Inn at approximately 150 ft above ground level. The aircraft then continued to descend over the powerline (struck by the aircraft in this accident) and manoeuvre at very low altitude.
• The accident flight data (Figure 6) captured a number of low-altitude and aerobatic manoeuvres, including an extremely low-level pass into a quarry, located north-east of Burrumbuttock. Previous flight data showed that the pilot had conducted that manoeuvre previously.
• The final recorded GPS track point for the accident flight was written at 1731, approximately 2 minutes prior to the accident. The aircraft altitude at that time was approximately 420 ft above ground level. The ATSB was unable to determine why the GPS ceased recording data at that point.

Figure 6: Accident flight path noting that the final 2 minutes of data was unable to be recovered

Image Source: Google Earth TM, edited by ATSB

Cockpit instruments

Laboratory examination of the cockpit instruments that were recovered from the aircraft wreckage was conducted at the ATSB’s facilities in Canberra. This type of examination may reveal fine details on an instrument face, or its internal mechanism, that may assist an accident investigation gain further information about the aircraft at the time of the accident. In this instance, no additional evidence was able to be derived.

Weather and environment

The Bureau of Metrology forecast at the time of the accident were for overcast conditions, with a light north-westerly wind of up to 3 kt (6 km/h). Witnesses reported weather conditions, including wind strength that were consistent with the forecast.

Sunset on 20 July 2014 for Burrumbuttock was calculated to have occurred at 1720 and last light^[5] was at 1748. The accident occurred at 1733. The position of the sun at the time of the impact with the powerline was calculated to be below the level of the horizon.^[6] Under overcast conditions and with the sun having set, the pilot’s ability to observe the fine detail of the electrical wires was likely to have been significantly diminished.

Minimum height requirements

Regulation 157 of the Civil Aviation Regulations 1988 outlines the requirements for conducting low flying. It states:

(1) The pilot in command of an aircraft must not fly the aircraft over:

(a) any city, town or populous area at a height lower than 1,000 feet; or

(b) any other area at a height lower than 500 feet.

The above requirements did not apply if weather conditions made it essential for the pilot to fly at a lower altitude. The regulation also did not apply if the aircraft was engaged in approved low flying operations, the aircraft was taking off or landing, or was engaged in the dropping of articles as part of a search and rescue operation. There was no evidence in the pilot’s documentation to indicate that the pilot was issued with a low-flying approval or permission from CASA. There was similarly no evidence to indicate that the pilot was engaged in any approved low-flying operations.

Powerlines

The powerline struck by the aircraft was not required to be marked in accordance with Australian Standard AS 3891.1 - 2008 Air navigation - Cables and their supporting structures - Marking and safety requirements. The electrical supply organisation reported that the section of powerline impacted by the aircraft consisted of a series of wooden poles, each supporting dual, three-strand, interwoven steel wire conductors (Figure 7). Installation drawings for the section of powerline showed that the poles had been erected and the electrical wires strung in 1994. The powerline was energised at the time of the accident and supplied electricity to a number of households in the immediate area. Each pole in the series was separated by distance of about 300 m.

The aircraft’s impact with the powerline dislodged both electrical wire conductors from their insulated tie-off points atop the cross-arm of one of the poles. One of the wires was severed from the impact and a large current fault was recorded at 1733:08 by the company’s electrical system. On-site measurements showed the point of impact to be 30 m to the nearest wooden pole and the wire height at the point of impact was estimated to be 9.5 m above the ground.

Emergency landing

It was known by some members of the local community that an emergency landing strip had existed in a relatively flat farm paddock that bordered the eastern edge of the Burrumbuttock town. The land owner of the paddock reported that the most recent aircraft to have landed on that strip was at least 20 years prior and that any remnants of the strip were probably concealed by crop.

An aerial survey flight was conducted during the on-site phase of the investigation which showed that the paddock was being used for cropping and pasture. No identifying markers or features could be observed that might otherwise indicate the location of such a strip in that paddock and the circumstances of the accident do not indicate that the pilot was seeking to conduct a forced landing.

Figure 7: The powerline (electrical wires arrowed) looking back along the flight path. A piece of the leading edge skin from the left wing is also shown

Source: ATSB

Wire strikes – an avoidable accident

The ATSB has investigated numerous accidents involving wire strikes from previous years. The investigations generally found that the pilot was involved in low flying for no identified operational reason and, in many of the occurrences, was more than likely aware of the presence of wires.

Between 1999 and 2008, there were 147 fatal accidents reported to the ATSB involving aerial work, flying training, private, business, sport and recreational flying in Australia. Of those fatal accidents, at least six were associated with unauthorised and unnecessary low flying; that is, flying lower than 1,000 ft (for a populous area) or 500 ft (for any other area) above ground.

In March 2013, the ATSB published an education series based on avoidable accidents. The first of the avoidable accident series was focused on accidents involving unnecessary and unauthorised low flying:

ATSB Avoidable Accidents No. 1 ‘Low-level flying’

Recognising the risks and hazards of low-level flying, CASA requires pilots to receive special training and endorsements before they can legally conduct low-level flying. In the accidents examined, many of the pilots did not have low-level training or an endorsement to do so, and none had a legitimate reason to be flying below the minimum limits. For most private pilots, there is generally no reason to fly at low levels, except during take-off and landing, conducting a forced or precautionary landing, or to avoid adverse weather conditions.

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3. Visual Meteorological Conditions is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft.
4. Night Visual Flight Rules (NVFR) permit flight at night under the Visual Flight Rules (VFR) using visual navigation augmented by the use of radio navigation aids. Flight under the VFR (by day or night) must be conducted in Visual Meteorological Conditions (VMC), that specify minimum inflight visibility and vertical and horizontal distance from cloud.
5. Last light is the time when the centre of the sun is at an angle of 6° below the horizon following sunset. At this time large objects are not definable but may be seen and the brightest stars are visible under clear atmospheric conditions. Last light can also be referred to as the end of evening civil twilight.
6. Astronomical information calculated through www.ga.gov.au. The sun had an azimuth of 293° (north north-west) and an elevation of 3° below the level of the horizon.

Safety analysis

The accident

While flying at low-level, the aircraft struck powerlines and lost control, resulting in the impact with terrain. The ATSB determined that the aircraft was capable of normal operation up until the wire strike. Upon striking the wires, the left wing aileron cable was severed, rendering the aircraft uncontrollable for the pilot. The aircraft subsequently rolled left and impact terrain at high speed. There was no pre-existing engine or airframe defects that would have contributed to the accident.

The witness descriptions and flight path of the aircraft indicated that the pilot had deliberately intended to overfly the Farmers Inn hotel. The considerable distance at which the aircraft travelled following the wire strike, as well as its configuration as found at the accident site, was not consistent with the pilot attempting to make an emergency landing. No operational reason could be identified for the pilot to fly at a height less than the minimum prescribed levels.

Analysis of the recorded GPS data indicated that the pilot had regularly flown at, and conducted hazardous low-level flying manoeuvres in the months preceding the accident. The pilot resided just outside the Burrumbuttock township and made regular flights over the town. It was therefore probable that he was aware of the presence and location of the powerline and the hazard that it posed. Powerline poles often provide good visual cues to enable a pilot to see the electrical wires. However, when the span between the poles is large this important visual cue is diminished or unavailable.

Additionally, at the time of the accident, the sun had set below the level of the horizon and the sky was overcast, thereby further reducing the ambient light. Under these conditions the pilot’s ability to detect the electrical wires was likely to have been significantly diminished.

Identifying the powerlines

Identifying powerlines and other similar obstructions from an aircraft in low-level flight is not a simple task. If the powerlines are in an area that is known to be a hazard for aircraft operations then they are required to be marked to enhance visibility. In this case, the powerlines were not required to be marked and, therefore, there was no enhancement to indicate their presence or assist in locating them. Factors such as windscreen visibility and environmental conditions can compound the problem of detection.

Wire strike accident investigations have often revealed that the pilot was aware of the presence and location of a powerline, but have nevertheless flown into it. The investigations have shown that even in the event that a subject pilot is able to detect the wires immediately prior to contact, the operating speed of the aircraft would severely limit the opportunity to react.

The effects of a wirestrike at low level are obvious; significant damage to the aircraft, usually leading to a loss of control and, because of the lower margin for recovery, subsequent impact with the ground or water. Pilots must keep in mind that not only do powerlines exist at low levels and in remote areas, they are also not easy to identify. Even against a clear blue sky, wires are difficult to spot for a number of reasons. Wires can oxidise to a blue/grey tinge and may blend into the background, or the wire may be obscured by terrain. Wires are very difficult to detect from the air and can be encountered in the most unexpected places in rural areas. Even if a pilot has spotted a powerline, the ability to judge its distance from the aircraft can be distorted by optical illusions or a lack of nearby visual reference points.

Low-level flying also presents fewer opportunities to recover from a loss of control compared to flight at higher altitudes. It takes time to react and to regain control of an aircraft should something go wrong.

Incapacitation

The postmortem medical examination revealed a pre-existing medical condition that could have led to the pilot being incapacitated during the flight in the moments leading up to the accident. Some coronary damage in the form of plaque haemorrhage and fibrin deposition to the pilot’s heart was found during the examination. Those changes are typically seen as an immediate precursor to a coronary artery thrombosis with the potential for a ‘heart attack’ and subsequent incapacitation. It was also possible that the arterial damage observed during the post-mortem examination had been induced by the impact forces experienced by the pilot.

While this pathological evidence cannot be discounted, the possibility of an incapacitating event is tempered by the facts surrounding the accident. The recorded data supports the numerous witness statements that the aircraft was being flown in a controlled manner and had been conducting low-level manoeuvring prior to the accident. Such operation of the aircraft was consistent with both witness accounts regarding previous flights and the recorded data from the GPS from previous flights.

Findings

From the evidence available, the following findings are made with respect to accident involving a Cessna 182L aircraft, registered VH-TRS, while being flown around Burrumbuttock, New South Wales on 20 July 2014. These findings should not be read as apportioning blame or liability to any particular organisation or individual.

Contributing factors

• While the pilot was operating at low level, the aircraft contacted electrical powerlines and collided with terrain.

Other factors that increased risk

• The pilot did not hold any approval to conduct low flying and had not received training in the identification of hazards or in the operating techniques for flight close to the ground.

Other findings

• There was no evidence of any defect with the aircraft that might have contributed to the accident.
• While it is possible that the pilot may have had a medical incapacitation event immediately prior to the accident, the aircraft was being operated in a manner consistent with previous flights undertaken by the pilot and at a level that provided little margin for error should such an event have been experienced.
• The powerline was not fitted with visual warning markers, nor was there a requirement for such markers in accordance with the Australian Standard.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• witnesses to the accident
• the next-of-kin
• the aircraft’s maintenance provider
• Civil Aviation Safety Authority (CASA)
• Bureau of Meteorology
• New South Wales Police Service

Submissions

Under Part 4, Division 2 (Investigation Reports), Section 26 of the Transport Safety Investigation Act 2003 (the Act), the Australian Transport Safety Bureau (ATSB) may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. Section 26 (1) (a) of the Act allows a person receiving a draft report to make submissions to the ATSB about the draft report.

A draft of this report was provided to the family of the pilot, the New South Wales Police Service and CASA.

Submissions were received from the family of the pilot and CASA. The submissions were reviewed and where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through: identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information  Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2015 Ownership of intellectual property rights in this publication Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this report publication is owned by the Commonwealth of Australia. Creative Commons licence With the exception of the Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this publication is licensed under a Creative Commons Attribution 3.0 Australia licence. Creative Commons Attribution 3.0 Australia Licence is a standard form licence agreement that allows you to copy, distribute, transmit and adapt this publication provided that you attribute the work. The ATSB’s preference is that you attribute this publication (and any material sourced from it) using the following wording: Source: Australian Transport Safety Bureau Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations. Where you wish to use their material, you will need to contact them directly.