The helicopters main rotor blades came into contact with a tree during a low-level fence inspection operation. The helicopter then descended out of control into a flooded river and submerged. The pilot and observer egressed safely from under the water.

The pilot reported that he had manoeuvred the aircraft to within about 10 metres of some tall trees beside the river, in order to give the observer the best possible view of a section of fence. At this point the helicopter yawed left and the main rotor blades struck a tree. Later the pilot said that he though the tail rotor blades may also have struck a tree. After the tree strike the pilot had insufficient control and was unable to prevent the aircraft descending sideways into the river.

The wreckage was not recovered from the river for several weeks, due to flooding and continuing torrential rain. Later examination of the wreckage did not reveal any pre-existing mechanical fault which may have contributed to the accident. The tail rotor assembly was found to be intact and attached to the boom. No evidence was found to indicate the tail rotor blades came into contact with the tree.

The pilot reported that he had accumulated about 6.5 hours flying for the day as well as having spent time on the ground on business at a number of locations. It had been very hot and turbulent throughout the day. He was relieved when he reached the Newman circuit and relaxed as the flight was nearly over. He joined the circuit on downwind and made a general downwind broadcast on MBZ frequency. The pilot thought he had completed the downwind checks correctly, but subsequent events indicated he had forgotten to lower the landing gear. During his finals checks he noticed that the landing gear lights were not illuminated but he assumed he had forgotten to turn the brightness back to the daytime setting. He realised the gear was still up when the propeller started to hit the ground. The landing gear warning horn, which had not sounded during the circuit, came on as the aircraft settled onto its lower fuselage.

The pilot reported that the landing gear waring horn may have been intermittent prior to the accident. He had made a note on the maintenance release to have it checked at the next periodic service which was due when the aircraft arrived back in Perth.

The pilot indicated that he felt that the factors leading to the accident were very straight forward. He was fatigued after a long day and had relaxed too much when he reached Newman. He had not payed sufficient attention to the operation of the aircraft and his fatigue had led to him rationalise the lack of landing gear lights as a rheostat setting rather than an indication the gear was still up. The failure of the landing gear warning horn to sound aggravated the situation.

FACTUAL INFORMATION

A Boeing 727 aircraft was en route from Melbourne to Brisbane via Casino and Coolangatta at flight level (FL) 350, while a Boeing 767 aircraft was en route to Brisbane from Sydney via BANDA and Coolangatta at FL370. The Boeing 767 was east of the Boeing 727's track and a few minutes behind on time estimates. There was a holding requirement at Brisbane with instrument landing system approaches in progress due to reduced visibility in passing rain showers.

The Brisbane sector radar position responsible for controlling the two aircraft was manned by a trainee controller undergoing final checks prior to rating. The trainee was being supervised by a current sector controller. However, the supervising controller was not the regular training officer for the trainee, and this was the first occasion that they had worked together. The Boeing 727 was initially vectored in a northerly direction for separation from other traffic but was shortly after instructed to turn right onto a north-easterly heading for arrival sequencing at Brisbane. The trainee controller intended to maintain the Boeing 727 on the north-easterly heading and provide a final heading to Coolangatta to meet the time required for sequencing. The Boeing 767 entered the controller's area of responsibility, and the crew requested descent to FL330 due to moderate turbulence.

The Boeing 767 was recleared to FL330. The new level was read back and the crew reported leaving FL370. The supervising controller discussed with the trainee the requirement to ensure separation between the two aircraft, since they were on converging tracks with the Boeing 767 crew cleared to descend through the Boeing 727's level. Discussion centred on whether the Boeing 767 should be radar vectored to parallel the track of the Boeing 727 until the required vertical separation of 2,000 ft was established. However, as there was more than sufficient horizontal separation (minimum separation required was 5 NM), the trainee controller elected to leave the Boeing 767 under the crew's navigation and to monitor the situation. The supervising controller believed it was reasonable to allow the trainee a level of latitude for independent action greater than he normally would for a trainee as the trainee controller had almost completed training. As separation between the two aircraft reduced to approximately 15 NM, the trainee controller's attention was diverted as he conducted coordination with another control position. As horizontal separation approached 8 NM and vertical separation was approximately 700 ft (with the Boeing 767 below the level of the Boeing 727) the trainee controller instructed the crew of the Boeing 767 to turn right onto a heading to parallel the track of the Boeing 727.

During this transmission the trainee controller incorrectly advised the Boeing 767 crew that the radar heading was for sequencing, instead of separation. The trainee controller requested the crew of the Boeing 767 to expedite descent and to confirm that the aircraft was turning right. The crew advised that the aircraft was turning right and expediting descent and, shortly after, reported sighting the Boeing 727 as horizontal separation reduced to approximately 4 NM with vertical separation of 1,600 ft. Horizontal separation reduced further to just over 3 NM before 2,000 ft vertical separation was re-established. The operating console was not fitted with an air-ground-air communication override facility to enable the supervising controller to intercede in trainee transmissions. Traffic information was not provided to either aircraft as the horizontal and vertical separation reduced to less than the standard. There was no Traffic Alert and Collision Avoidance System (TCAS) report from the B767. ANALYSIS The trainee's use of the term "sequencing" instead of "separation" did not provide the level of notice to the crew of the Boeing 767 that was warranted under the circumstances. Had the crew been advised that the heading change was for separation they may have been more expeditious in complying. However, the situation should not have been allowed to develop to the stage where immediate action was required to maintain separation.

Similarly, the inclusion of a console facility that would enable the supervising controller to override the trainee's transmissions to establish appropriate separation measures would have been beneficial. But again the situation should not have developed to the extent that such facilities were essential. Both controllers had discussed separation requirements for the two aircraft, and the trainee was satisfied with monitoring the situation. The supervising controller deferred to the trainee's judgement because he understood the trainee was close to achieving a rating. However, the trainee became distracted, and the supervising controller did not adequately monitor the trainee's subsequent control actions.

The supervising controller could have emphasised to the trainee the need to give priority to the radar display and to maintain a high scan rate to ensure separation. However, the situation would have been still totally dependent on the performance of the trainee and the supervisor. As the trainee became distracted by coordination to the detriment of control, the supervising controller was unable to intervene adequately, and separation was lost between the aircraft. Monitoring of the flight paths did not provide an adequate level of separation assurance. Early implementation of an altitude requirement or a radar heading (to parallel the track of the Boeing 727) to the crew of the Boeing 767 would have been an adequate separation assurance technique. Use of separation assurance techniques would have greatly improved the possibility of the two aircraft remaining separated.

SIGNIFICANT FACTORS

1. The supervising controller did not adequately monitor the trainee controller's actions or ensure that a suitable separation assurance technique were employed.

2. The use of inappropriate radiotelephony phraseology by the trainee controller did not impart to the crew of the Boeing 767 the need for expeditious compliance with instructions.

3. The lack of a communications override facility deterred the supervising controller from implementing timely remedial action.

SAFETY ACTION

The Bureau of Air Safety Investigation is continuing its investigation into the provision of adequate communications override facilities for air traffic control training officers. This is intended for all consoles where on-the-job training of air traffic controllers is likely to occur.

The crew were carrying out rappelling recurrency training at the time of the accident. During the first of several planned descents down the rope, from 70 ft, the rescue crewman misjudged his speed and landed heavily, resulting in a fracture of his right leg.

The speed during descent is normally controlled by the degree of braking applied to the rope by one hand. The braking required is judged on 'feel' through the glove. The rescue crewman was wearing two pairs of gloves as the pair he normally wore were slightly frayed. He had previously only worn a single pair during rappelling activities. It is probable that the extra pair of gloves altered the 'feel' causing the crewman to misjudge his descent rate.

The crew were all endorsed for rappelling activities, a pre-flight briefing had been completed, and activities were being conducted in accordance with the operations manual. However, the rescue crewman's rappelling currency had lapsed.

Safety Action

The operator has introduced a flying safety instruction requiring crew, who's currency in rappelling has lapsed, to complete at least three descents from a suitable static platform prior to helicopter operations. In addition, the first rappel from the helicopter will be completed from 30 ft instead of 70 ft.

The operator is also researching the use of mechanical braking devices as an alternative to the 'feel' system.

The purpose of the flight was to aero tow a glider from a paddock where it had made an out landing. Prior to take-off the pilot measured the paddock twice by pacing. The paddock was wedge shaped with powerlines running along the two longer boundaries. There was also a powerline spanning the paddock towards the narrow end of the wedge. Despite walking under this powerline while pacing the paddock, the pilot did not see it.

Take-off was into the northwest which provided the longest take-off run and was also into a 5-7 kt wind. After take-off the pilot held the tug down to gain speed. He then saw the powerline but too late to avoid it. After impact with the powerline the tug hit the ground and was substantially damaged.

The pilot said that in the take-off direction, the powerline was below the horizon against a background of hills which made it almost impossible to see.

VH-IGJ departed Canberra CTA on the Canberra Yass track 20 miles from Canberra and cruising at 4500 ft. Approximately five minutes later VH-IJA departed Canberra CTA on the same track, 20 miles from Canberra and cruising at 6000 ft. At that time the controller noted a radar return two miles ahead of IJA, orbiting on the Canberra Yass track, also at 6000 ft but climbing.

Flight Service was advised so as traffic could be passed to IJA and Flight Service was also asked to contact IGJ. The pilot of IGJ reported to Flight Service at 6700 ft. The base of CTA was 6000 ft at that position. The radar return was identified as IGJ. Shortly afterwards IGJ left CTA no descent.

Factors

The pilot of VH-IGJ initiated a climb into controlled airspace without a clearance.

The Cherokee departed from runway 14 to track to Flat Top Island, 4 NM east of Mackay, to carry out Airwork. Soon after, a Brasilia reported ready to take-off from the same runway, with the intention of tracking to Rockhampton via the 131 VOR radial. The aerodrome controller cleared the Brasilia to take-off after observing the Cherokee appeared to be established on track to Flat Top Island.

The pilot of the Brasilia reported that as he turned left to intercept the 131 VOR radial, he noticed the VOR had apparently failed and attempted to resolve the problem. Soon after, the copilot reported another aircraft immediately ahead. The pilot saw a Cherokee about 200 metres away at the same altitude, but slightly to the left, and passing from left to right. He took immediate evasive action by turning left to pass behind the other aircraft.

The investigation established that the instructor in the Cherokee had been concentrating on the instructional sequence and had not continued on track to Flat Top Island as cleared. The Cherokee had been subsequently turned onto a south-westerly heading, which conflicted with the flight path of the departing Brasilia.

History of the flight

Prior to landing West Sale, the crew were advised by air traffic control that the weather conditions at Latrobe

Valley, their next landing point after West Sale, were wind 270/5, cloud seven oktas at 800 ft and visibility 5000 m. 

Considering these conditions, the pilot in command elected to fly from West Sale to Latrobe Valley, a distance of 25 NM, at 4000 ft and make an NDB approach at Latrobe Valley. Weather conditions enroute were considered marginal for a VFR flight below the cloud base.  The minimum descent altitude for the NDB approach at Latrobe Valley is 1000 ft so the crew were aware they may not get into Latrobe Valley.

When they taxied for departure at West Sale, the crew were advised by air traffic control that another aircraft had flown to Latrobe Valley visually below 1000 feet above ground level and made a successful approach and landing, about 40 minutes previously.  On the basis of this information, the pilot in command decided to follow the same procedure.  An alternative course of action, in the event that visual reference was lost, was planned and briefed prior to departure.  The aircraft then departed and according to the crew, proceeded visually below the cloud at a reduced airspeed of 170 to 180kt, at 500 to 700 feet above ground level with a flight visibility of about 5000 metres.

Approaching Latrobe Valley all appropriate checks were completed.  Calculated landing weight was 6400 kg which equated to a target threshold speed (Vref), pilot in command could not recall any Vref minus calls. The captain did not respond to Vref minus calls by application of power.

Touchdown was heavy and both crew members agreed there had been no landing flare.  The co-pilot sensed an increased sink rate shortly before touchdown but did not note the vertical speed indication.  The crew found no damage to the aircraft during a post flight inspection.  However, the day after the occurrence, minor damage consistent with a heavy landing was discovered.  An inspection of the runway threshold, after the occurrence, revealed that the aircraft had touched down just prior to the threshold and had hit and broken two frangible runway end lights.

The investigation

As part of the investigation, the flight data recorder was read out.  This revealed that at touchdown, airspeed had reduced to below Vref and sink rate was high (approx:102 kt/1000 ft/min+).  Runway 03/21 at Latrobe Valley is 1430 metres long, is narrow (an 18 metre wide sealed section), has no touchdown zone markings or approach guidance lighting (e.g. TVASIS).  Visibility was reported by the crew to be about 5000 metres at the airfield and deteriorating.  Light rain was falling.  The pilot in command did not turn on the windscreen wipers because on long final approach, speed was in excess of the windscreen wiper limit speed and later on final he was reluctant to divert his attention from flying the approach to the wiper control switch.

The crew did not activate the runway lighting which may have assisted with approach angle guidance.  The pilot in command stated that he was aiming to touch down just past the piano keys (the threshold) due to the runway being wet, narrow and having a downslope (0.4% down to the southwest).

The pilot in command acknowledged that he clearly misjudged the approach in that the aircraft touched down before he had initiated a landing flare.  It is possible that there may have been a visual illusion created by the combination of a narrow runway, reduced visibility and rain on the windscreen.

Safety action

As a result of its investigation the company has instituted the following measures:

1. The Metro Operations Manuals are being amended to reflect the requirement to call excessive sink rate on final approach.
2. The operator has distributed an aircrew circular describing techniques which assist in overcoming visual illusions associated with approaches to narrow runways, particularly in reduced visibility conditions.
3. Runway lights are to be activated on narrow runways to assist in assessing approach angle.
4. All flight crew members are to complete crew resource management courses.

FACTUAL INFORMATION

A BAe146 (VH-NJN) was maintaining flight level (FL) 280 on a flight from Cairns, Qld to Ayers Rock, NT.  The crew reported over Alice Springs at 1236 CST with an estimate for Ayers Rock of 1312.

A second BAe146 (VH-JJW) departed Alice Springs at 1237 for Ayers Rock and climbed to FL240.

Both aircraft were under the control of Melbourne air traffic control (ATC) sector 5 which was staffed by a trainee under the supervision of a team leader. The aircraft were subject to procedural control procedures.

The trainee controller coordinated the two aircraft positions with flight service, giving the estimated times of arrival (ETA) at Ayers Rock as 1312 for NJN, and 1318 for JJW.   An error was made in the time of arrival for JJW in that the trainee incorrectly added the flight plan time intervals.  The correct estimate was 1316.  This error was not detected by the team leader.

When both aircraft were on the control frequency, the trainee checked their respective DME distances, this resulted in NJN being 22 NM ahead of JJW. As the aircraft were of the same type, a suitable standard (15 NM) had been established to allow the descent of NJN through the level of JJW.

At 1253, the crew of NJN requested descent.  This was approved by Melbourne control and the aircraft commenced descent at 1255.  At 1256, the crew established contact with flight service and advised their ETA as 1311.

At 1259, the crew of JJW requested descent.  This was approved by Melbourne control and descent was commenced at 1302.  At 1303, the crew contacted flight service and advised their ETA as 1312.  The flight service officer then passed traffic information on three aircraft, including NJN, to the crew of JJW.

The flight service officer also passed traffic information on JJW to the crew of NJN who then transferred to the Mandatory Broadcast Zone (MBZ) frequency.

Shortly after, the crew of JJW also changed to the MBZ frequency and commenced a DME check with the crew of NJN.  This resulted in the aircraft being 12 NM apart while JJW was passing FL180. Based on this information, the crew believed that NJN passed through their flight level in controlled airspace with only 12 - 14 NM separation and therefore a breakdown in separation had occurred.

As the aircraft approached Ayers Rock, in the MBZ, a pilot initiated distance check revealed that the aircraft had reduced the separation to 4 NM.  Both aircraft landed without further incident.

ANALYSIS

Air Traffic Control

The two minute error made by the trainee in the ETA for JJW at Ayers Rock was not considered to be a factor in this occurrence because the flight service officer passed traffic information based on the pilot reports not the ATC estimates and the DME check was independent of the ETA.

The controller established a correct separation standard (15 DME) for aircraft of the same type and issued control instructions appropriate to the circumstances.  It is probable that the correct distance for this standard was maintained throughout the period of flight within controlled airspace.

The flight progress strips that the controllers had for reference did not differentiate between the various series of BAe146 aircraft.  Additionally, the Manual of Air Traffic Services only published some of the various profile speeds for the BAe146 series of aircraft and these were displayed in the radar control section, not specifically in the procedural control sections. Flight Service

The flight service officer provided traffic information in a correct manner appropriate to the circumstances.

Aircrews

Both crews acted in accordance with ATC instructions and operated their aircraft within company profiles.

Flight Plans

The flight plan held by the crew of JJW varied to that held by ATC in that the ETA Ayers Rock on the crew's plan was 1312 and on the ATC plan was 1316. The reason for this discrepancy was that ATC took the overall block time provided by the flight plan and had their computer calculate the ETA at each reporting point based on the various distances from one point to the next.  As the company provided a two minute manoeuvring time at the departure and destination aerodromes, a four minute difference existed between the times provided to ATC in the flight plan and the time the pilot held in the cockpit.  The pilot based his reporting calculations on the time of departure and had, therefore, already accounted for the two minute manoeuvre prior to advising his actual departure time to ATC. ATC then added the computer generated time intervals to this reported time of departure and the erroneous situation was complete.

Aircraft Performance

ATC reference data for the BAe146 aircraft indicated that there was a similarity of performance between the operating profiles of the various series of BAe146 aircraft operated by all companies.  This was not the case, as the operating profiles indicated that a difference of up to .08 Mach can exist while two aircraft are on descent.

This performance differential could lead to a degradation in certain separation standards such as the 15 DME standard used in this case.

Additionally, the reference material was only contained in the radar sections of the Manual of Air Traffic Services.

SIGNIFICANT FACTOR

The air traffic controllers had insufficient information to indicate that significant closing between aircraft may occur.

SAFETY ACTION

As a result of the investigation the following action was taken:

Local ATS management introduced an amendment to the Manual of Air Traffic Services (MATS) Local Instructions which specifies the full range of performance options for BAe146 series aircraft.

Airservices Australia has undertaken to amend MATS to ensure that the information on BAe146 aircraft is adequately displayed for controller reference.

Airservices Australia and the operating company of JJW are consulting over the format for flight plan submission so that both parties understand the requirements and operating methods of the other.  This process should ensure that controllers and aircrew have the same initial information on which to base their operational requirements.

Due to poor lift conditions the pilot was forced to make an outlanding. He selected what appeared to be a suitable paddock and noted there was a powerline running parallel to the selected landing direction. Late on final approach, the glider hit another powerline that the pilot had not seen. This line was a three-wire spur line crossing the landing path at 90 degrees and originating from an area of trees.

Significant Factors

The following factors were considered relevant to the development of the accident:

1 The pilot had to make an outlanding due to poor lift conditions.

2 The pilot did not see the powerline before his aircraft collided with it.