Separation issue

The pilot of VH-LGI, enroute from Maningrida to Darwin, reported to Adelaide Flight Service that he had experienced a breakdown in separation with an aircraft travelling in the opposite direction.

He was advised there was no other instrument flight rules traffic in the area, and that the aircraft was VH-AMQ operating under the visual flight rules on a SARTIME flight, and therefore not given as traffic.

Although both aircraft had made all necessary radio calls, the conflict occurred at a Flight Information Service area boundary when opposite direction traffic are monitoring different VHF radio frequencies.

Factual Information

VH-SQV departed Bankstown for Coffs Harbour at 0855 EST initially via West Maitland then operating outside controlled airspace (OCTA).  Contact was established with Flight Information Service Sector 4 (FIS4) and the pilot requested a clearance into controlled airspace (CTA) via the 015 radial of the Sydney VOR on climb to 9,000 ft.

The Flight Service Officer (FSO) co-ordinated the request with Williamtown air traffic control (ATC) which approved the intent but withheld an airways clearance until the aircraft was closer to its airspace.  This intention was passed by FIS4 to the pilot of VH-SQV who changed heading to intercept the 015 radial and continued to climb beneath the CTA steps.

VH-TQM departed Williamtown for Sydney at 0916 and was cleared by Williamtown ATC to leave and re-enter CTA on climb to FL120.  This clearance was given after co-ordination with Sydney ATC but, due to a combination of workload on other tasks and the short taxi distance to runway 30 at Williamtown, FIS4 did not receive the co-ordination until two minutes after VH-TQM had departed.

The co-ordination was completed at 0919 and Williamtown ATC informed FIS4 that it would hand the aircraft (VH-TQM) off early for traffic, but did not mention the callsign.  This occurred immediately after discussion regarding VH-SQV with the FSO.

At 0919, following the above co-ordination, the FSO, having already given the pilot of VH-SQV traffic on

VH-TQM, asked him to report VH-SQV's distance from Sydney.  The pilot incorrectly advised his distance as 65 DME Sydney which is approximately 10 NM south of Williamtown and in the Williamtown ATC area of responsibility (it is likely that he transposed an indicated "56" to "65" DME).  The FSO believed the aircraft was closer to Williamtown than it actually was and immediately instructed VH-SQV to contact Williamtown ATC for an airways clearance. This transfer occurred at 0920.

Also, at 0920 the crew of VH-TQM contacted FIS4, as instructed by Williamtown ATC, and reported at 12 NM south of Williamtown.  The FSO therefore calculated that, as VH-SQV had reported 10 NM south of Williamtown approximately 1 minute earlier, the two aircraft had passed and that Williamtown ATC must have separated the aircraft in their airspace before giving the crew of VH-TQM its frequency transfer.  The pilot of VH-TQM then reported leaving 7,500 ft and the FSO instructed him to contact Sydney ATC as per normal operation.

At 0921 while making the transfer to Sydney ATC, the crew of VH-TQM observed the other aircraft and estimated it was approximately 500 m away and about 1,000 ft below them. This sighting occurred at a distance of 15 NM south of Williamtown.

The pilot of VH-SQV contacted Williamtown ATC at 0921 and gave a correct position of 60 DME Sydney. The aircraft was identified by Williamtown ATC in that position which was 3 NM south of its airspace. This identification was at 0921:50 seconds.

Radar analysis indicates that at 0921:31, the aircraft were 3 NM apart with 900 ft vertical separation.

Analysis

The FSO acted in accordance with the incorrect position report from the pilot of VH-SQV and, had that report been correct, the assumption made would have been reasonable. However, the pilot appears to have transposed the digits on the DME reading and reported 65 DME when he was 56 DME. He made a correct report of 60 DME to Williamtown later in the sequence of events.

For aircraft departing via non-controlled airspace, Williamtown ATC is required to make the co-ordination while the aircraft is taxiing.  In this case the Tower controller had to complete another task before initiating this co-ordination.  When he was able to do this the FSO was busy and unable to answer the intercom line for about 2 minutes.  This resulted in VH-TQM departing before FIS4 received the information and little time remained for the passing of traffic information.  The co-ordination was therefore rushed and did not specify the callsign or adequately clarify the traffic information requirements.

A further factor was the relatively short distance for VH-TQM to taxi in order to reach the threshold of runway 30 and then the short distance between take-off and the Williamtown CTA boundary.

Significant Factors

1. The pilot of VH-SQV gave an incorrect DME distance from Sydney when responding to a position report request from FIS4.
2. The co-ordination for VH-TQM between Williamtown ATS and FIS4 was delayed due to workload and was not of a specific nature.

Safety Action

As a result of the investigation Williamtown ATC has issued a Local Order that, in specified cases, will ensure that co-ordination between Williamtown ATC and Sydney ATS is completed before an aircraft departs.

As a result of this and other occurrences (9400523) the Civil Aviation Authority and the RAAF were advised of the co-ordination deficiencies by Safety Advisory Notice SAN 940093.  The SAN states, in part:

The Bureau of Air Safety Investigation suggests that the CAA and the RAAF conduct a joint review of their procedures with respect to:

(a) The co-ordination of traffic information concerning aircraft departing Williamtown CTR for possible climb or cruise OCTA.

Factual Information

Sequence of Events

The crew of VH-SSV planned for a flight from Bankstown to Coffs Harbour as VH-SSW. The plan nominated flight within controlled airspace (CTA). A change of aircraft occurred and, after taxiing to the holding point, it was established that air traffic control (ATC) would require a delay before issuing a departure clearance into CTA. The crew therefore decided to proceed outside controlled airspace (OCTA) and departed at 0642 ESuT, climbing below the CTA steps.

At 0646 the aircraft passed the Hawkesbury Bridge, and the crew transferred to the flight service (FS) area frequency of 125.7 MHz. They requested that the flight service officer (FSO) inquire of Sydney Sector 1 (Sec 1) if an airways clearance was available as they had planned about 70 minutes earlier. This request was not relayed to Sec 1 until 0654 due to the workload on FS 4. At the time of the co-ordination, the sector controller had not received the flight plan details at the console.

Also at this time, the FSO passed traffic information on two IFR aircraft which were in the area and in possible conflict. Consequently, the crew of one of these aircraft (VH-KZQ) and the crew of VH-SSV arranged mutual vertical separation. During this time, the crew of VH-SSV reported maintaining 6,000 ft to FS.

VH-TQL had planned a flight from Williamtown to Sydney at FL120 and at 0647 the crew reported taxiing at Williamtown on area frequency as Williamtown ATC had not yet commenced duty. RAAF ATC were due to commence services at 0700. This taxi call is required to be co-ordinated with Sec 1, and this was completed at 0651, delayed due to workload on FS 4.

At 0653 the crew of VH-TQL reported to FS its departure of 0652 and, as the airspace was uncontrolled, they were required to remain OCTA until Sec 1 could issue an airways clearance. As a result, VH-TQL was levelled at 8,000 ft to remain OCTA while awaiting airways clearance.

The FSO providing the FS 4 service had received from Sec 1 an expectancy  that VH-TQL would be given an airways clearance with little or no delay and therefore instructed the crew to contact control on 123.4 MHz on reaching 8,000 ft for a clearance and asked the crew to report approaching 8,000 ft before leaving his frequency. 123.4 MHz is Sydney Arrivals Control and the responsibility for informing that controller lies with Sec 1.

At 0654 FS 4 co-ordinated with Sec 1 regarding the request from VH-SSV for an airways clearance. This was the first time that Sec 1 had been passed information on this aircraft but agreed to take the aircraft on frequency for processing. FS 4 instructed the crew of VH-SSV to contact control on 126.9 MHz (Sec 1) for a clearance. It is the responsibility of Sydney Departures Procedural control to inform Sec 1 when an aircraft that has planned in CTA from Bankstown departs OCTA and requires a clearance en-route. This co-ordination was not carried out.

As the crew of VH-SSV were transferring frequencies, they observed that they had passed the next control area step and elected to climb to 8,000 ft OCTA while awaiting their airways clearance from Sec 1. Due to a delay in the issuing of the clearance, the aircraft was levelled at 8,000 ft in order to remain OCTA. As their track was 002 degrees, both 8,000 ft and their previous cruising level of 6,000 ft were contrary to the table of hemispherical cruising levels.

At 0655 FS 4 co-ordinated the departure time of VH-TQL with Sec 1. The Sec 1 controller found that he had four aircraft OCTA all wanting airways clearances. He decided to instruct all four to remain OCTA until he had identified them on radar so that he could guarantee adequate separation within CTA. This resulted in a short delay for both VH-TQL and VH-SSV while on separate control frequencies and both maintaining 8,000 ft on conflicting tracks.

While Sec 1 was co-ordinating the clearances for the two aircraft with arrivals control, the initial radar returns indicated that the aircraft were in close proximity and on converging headings. The sector controller issued VH-SSV with a radar vector OCTA for collision avoidance. Traffic information was passed to both crews, and a mutual sighting was achieved during the turn manoeuvre.

The aircraft passed approximately 600 m apart at the same altitude.

Flight Planning

It is common practice for pilots to plan IFR in CTA ex Bankstown and then elect to proceed OCTA when ATC issue a delay for an airways clearance. It is also common practice for crews to hold a second, OCTA, plan in the cockpit for such eventualities. However, they do not submit this OCTA plan as the pilots prefer to operate IFR in CTA and they believe that ATC will always send them OCTA if such a choice exists on the flight plan. This causes problems in the distribution of flight details to FS.

Co-ordination

When an aircraft departs OCTA from Bankstown having planned in CTA, Bankstown ATC are required to pass the details to Sydney FS and Departures Procedural. Departures Procedural then passes this information on to Sec 1 for processing.

Hemispherical Levels

IFR aircraft are required to be flown in accordance with the table of hemispherical cruising levels. On this occasion the crew of VH-SSV chose to fly at a non-hemispherical level. The correct altitudes for their track would have been 5,000 ft and 7,000 ft in lieu of 6,000 ft and 8,000 ft.

Change of Level OCTA

The crew of VH-SSV were maintaining 6,000 ft when transferred by FS to control frequency. Shortly after, they initiated climb to 8,000 ft to remain OCTA in the belief that a clearance would be given by the time they reached that level, however the delay in obtaining the clearance resulted in the aircraft maintaining 8,000 ft. Neither the crew nor ATC informed FS of this change in altitude, which is contrary to requirements.

The FSO did not pass traffic to either aircraft in the belief that they were separated by IFR cruising levels, but he was aware of the requirement for VH-SSV to pass through the level of VH-TQL once ATC issued approval for climb into CTA. He considered that ATC would separate the aircraft on climb as both were on control frequencies with an expectancy of an airways clearance almost immediately (as this was normal practice).

Control Frequencies/Airspace Configuration

The two aircraft were transferred to separate ATC frequencies by the FSO. This was common practice but was not in accordance with Local Instructions. It resulted in neither crew being able to hear transmissions involving the other at a time when they were on conflicting tracks. The correct procedure would be for both aircraft to contact Sec 1 whose airspace they were about to enter.

FS Workload

The FSO was rostered to perform the FS 4 duties on his own until 0800 when a relief officer commences duty. The workload builds up after 0630 each morning and becomes very busy from approximately 0645. It has become common practice for the FS 4 operator to request the assistance of the Team Leader to act as co-ordinator during this period.

One reason for this rise in workload is that Williamtown ATC commence duty at 0700 each weekday and this results in an added workload for the FS 4 operator in that an update of all traffic in the Williamtown area is required to be passed to ATC. The process for passing this information is very formal and convoluted.

Findings

1. No flight plan for VH-SSV to depart Bankstown OCTA was submitted.
2. Sydney Departures Procedural did not co-ordinate the departure of VH-SSV as required by Sydney District Local Operating Instructions.
3. The FSO was experiencing a period of heavy workload.
4. The two aircraft were transferred to different control frequencies.

Significant Factors

1. The crew of VH-SSV elected to fly at a non-hemispherical altitude.
2. Neither the crew of VH-SSV nor ATC informed FS4 that the aircraft had changed level while remaining OCTA.
3. The FSO did not pass traffic information on either aircraft to the crew of the other.

Safety Action

As a result of the investigation the following Safety Advisory Notices were issued:

SAN 940093: The Bureau of Air Safety Investigation suggest that the Civil Aviation Authority and the RAAF conduct a joint review of their procedures with respect to:

1. the coordination of traffic information concerning aircraft departing WLM CTR for possible climb or cruise OCTA;
2. notification of the opening of military airspace, with particular reference to RAAF/FIS coordination.

SAN940079: The Bureau of Air Safety Investigation suggests that the Civil Aviation Authority conducts a consultative meeting with local industry to discuss the practices and procedures used for IFR operations in Sydney airspace. This meeting should particularly address those operations departing Bankstown OCTA.

The Bureau issues the following, additional, Safety Advisory Notice:

SAN940095: The Bureau of Air Safety Investigation suggests that the Civil Aviation Authority review the staffing procedures at Flight Service Units to ensure that they are adequately manned during known periods of high workload.

On 3 July 2014, at about 1940 Eastern Standard Time an instructor and student pilot of a Bell 206 helicopter, registered VH-XJA (XJA), approached Sunshine Coast Airport, Queensland to conduct night circuits. An Airbus A320 aircraft, registered VH-VGJ (VGJ), was inbound to Sunshine Coast from Melbourne, Victoria via the area navigation (RNAV) required navigation performance approach to runway 18. When about 30 NM from Sunshine Coast, the first officer of VGJ broadcast on the common traffic advisory frequency (CTAF), inbound and did not receive a response.

When about 10 NM from the runway, on a downwind leg and approaching a base turn for runway 18, the first officer broadcast on the CTAF that VGJ had left 3,800 ft and was conducting an instrument approach to runway 18, expecting to land at time 2001, and did not receive a reply.

The instructor of XJA heard the call from VGJ and assumed that the aircraft was then about 15 NM away. He expected the crew of VGJ would subsequently broadcast when 10 and 5 NM from the runway, and he elected to continue the circuit and monitor the CTAF for those calls.

The instructor of XJA broadcast when on a 3 NM final, but the crew of VGJ did not hear this call. About 70 seconds later, the first officer of VGJ broadcast on a 2 NM final. Hearing this call, the instructor of XJA turned and sighted the landing lights of VGJ close behind, diverged to the right and commenced a climb. Radar data indicated that the two aircraft passed at an altitude of about 200-300 ft with a lateral separation of about 370 m.

This incident highlights the importance of using both unalerted and alerted see-and-avoid principles and maintaining a vigilant lookout at all times.

Aviation Short Investigations Bulletin - Issue 36

At about noon on 3 July 2014, an instructor and student were conducting training in the circuit at Roma Airport, Queensland, in a Skyfox Aviation CA25N aircraft, registered 24-3265. At the same time, a PA-28R, registered VH-WJO, was inbound to Roma Airport for a landing. The conditions were fine and clear.

As the PA-28R approached the airport, the CA25N instructor and the pilot of the PA-28R exchanged information regarding their respective positions and intentions on the Roma Airport Common Traffic Advisory Frequency (CTAF). During this exchange of information, the pilot of the PA-28R inadvertently miscommunicated his position, which left the CA25N instructor with an inaccurate perception of the position of the PA-28R and a misunderstanding with respect to the intentions of the PA-28R pilot. Similarly, based upon his interpretation of the information exchanged on the CTAF, the PA-28R pilot believed that he would be clear of the CA25N as he joined the circuit.

Despite their efforts, the CA25N crew and the PA-28R pilot were unable to sight the other aircraft until the downwind leg of the circuit when the CA25N instructor saw the PA-28R pass from left to right, about 100 metres ahead and about 200 ft above the CA25N. The CA25N instructor was then able to inform the pilot of the PA-28R of the relative position of the CA25N, allowing the pilot of the PA-28R to then sight the CA25N over his left shoulder. Both aircraft then continued for an uneventful landing, the CA25N landing ahead of the PA-28R which flew a wider circuit.

Although the CA25N instructor and PA-28R pilot were communicating on the CTAF and attempting to establish visual contact, separation seems to have been compromised on this occasion due to the limited effectiveness of the CTAF communications and the limitations of each pilot’s lookout. Lookout effectiveness was probably compromised by a combination of CTAF miscommunication, the geometry of the event and sun glare.

This incident highlights the importance of an effective lookout, and accurate and timely communication. These are fundamental pillars supporting the principles of alerted see-and-avoid.

Aviaiton Short Investigations Bulletin - Issue 37

On 21 May 2014, a Grob G115, registered VH-BBJ (BBJ) and a Grob G115, registered VH-ZIM (ZIM) were both conducting dual flight training, in the northern training area, near Merredin aeroplane landing area (ALA), Western Australia.

The student pilot of ZIM was conducting a pre license general flying progress test. After completion of the training area component of the test, in the northern training area, the student pilot navigated to the inbound reporting point near Burracoppin, at an altitude of about 3,500 feet above mean sea level (AMSL). During the flight, the student became disorientated and tracked toward the town of Merredin, instead of Merredin ALA. The student was not able to locate Merredin ALA and the instructor provided assistance by pointing out land features. 

At about the same time, the instructor of BBJ had just completed basic instrument flying with the student in the northern training area. The student tracked to the south-east, toward Burracoppin at 3,500 feet AMSL. The aircraft remained clear of the inbound track from Burracoppin to Merredin ALA. The instructor broadcast their intentions on the common traffic advisory frequency (CTAF).

As ZIM turned to navigate toward Merredin ALA, the instructor observed BBJ, which appeared to take up almost the entire windscreen. The instructor took over control of the aircraft, and took evasive action, pushing the control column forward and descending. At about the same time, the instructor of BBJ observed ZIM straight ahead, at or just below the horizon coming towards them. The instructor also took over control of the aircraft, to take evasive action, pulling the control column rearward and climbing.

Both aircraft returned to Merredin without further incident. The pilots of both aircraft were uninjured and neither aircraft was damaged.

The serious incident highlights that it is difficult for pilots to spot another aircraft through visual observation alone.

Aviation Short Investigations Bulletin - Issue 38

On 5 October 2013, a Piper PA-44 aircraft, registered VH-CZH (CZH), was enroute to Rottnest Island, from Perth, Western Australia, to conduct instrument flight rules (IFR) navigation aid (navaid) training. On board were a flight instructor and student.

There was other IFR training aircraft on the Rottnest Island common traffic advisory frequency (CTAF) when CZH arrived over the navaid to commence the practice non-directional (radio) beacon (NDB) training. Both the instructor and student made frequent broadcasts on the CTAF to advise other traffic of the aircraft’s position and their intentions. The weather was instrument meteorological conditions and conditions were deteriorating as a large cold front was moving rapidly in from the south-west.

At about 1509 Western Standard Time (WST), as CZH was inbound in the holding pattern at 2,000 ft, Perth Centre air traffic control (ATC) advised the crew that an IFR Mooney M20 aircraft, registered VH‑DJU (DJU), was inbound to Rottnest Island, and would be on descent from 3,000 ft, for instrument navaid training. The estimated time of arrival overhead the NDB would be 1518. The instructor in CZH acknowledged this traffic information.

Shortly after, the instructor and student in DJU requested a descent to 2,000 ft due to severe turbulence at their current level. This descent took DJU from controlled to uncontrolled airspace and thus a change from ATC separation responsibility, to pilot responsibility for maintaining separation in the Rottnest Island area.

When the crew in CZH had not heard from DJU on the CTAF, the instructor tried unsuccessfully to raise them on this frequency. He then contacted ATC on the Perth Centre frequency, who provided traffic information. The pilots subsequently arranged mutual separation

The ATSB SafetyWatch campaign highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns is safety around non-controlled aerodromes. Insufficient communication between pilots, and breakdowns in situational awareness were the most common contributors to occurrences in the vicinity of non-controlled aerodromes.

Aviation Short Investigation Bulletin - Issue 26

On the evening of 7 October 2013, the pilot of a Cessna 172 aircraft, registered VH‑NUU (NUU), commenced night circuits at Archerfield Airport, Queensland. He reported that there were also four other aircraft and a helicopter conducting night circuits at the time. The pilot reported that the aircraft in the circuit were flying a ‘modified’ due to a strong tailwind and to make allowances for a helicopter that had been conducting stop-and-go circuits.

At the same time, the pilot of a Beech F33A aircraft, registered VH‑ZBZ (ZBZ), inbound to Archerfield, was advised by air traffic control that there were four or five aircraft in the circuit area. ZBZ joined the circuit between an aircraft on downwind and another on upwind. The pilot of ZBZ reported that he had the aircraft in front of him (NUU) sighted on downwind and extended the downwind leg to maintain separation with NUU.

NUU turned onto base and about 20 seconds later, the pilot of ZBZ also broadcast that he was turning onto base. Soon after, the pilot of ZBZ broadcast that he was established on final. At that time, he had sighted an aircraft well ahead on late final and believed it was NUU. The pilot of NUU immediately broadcast that he was on final.

The pilot of ZBZ then saw NUU below his aircraft. The pilot of ZBZ conducted a go‑around and NUU continued the approach.

Airservices Australia surveillance data indicated that the vertical separation reduced to 300 ft.

Maintaining a vigilant lookout at all times and standardisation of the circuit pattern is important for safe operations in the vicinity of non-towered aerodromes.

Aviation Short Investigation Bulletin - Issue 25

On 12 September 2013, at about 0930 Eastern Standard Time, the pilot of an Ayres S2R aircraft, registered VH-WBK (WBK), commenced aerial agricultural operations on a property about 37 km south-southwest of Horsham aerodrome, Victoria.

At about the same time, the operator of an unmanned aerial vehicle (UAV), Sensefly eBee 178, arrived at the Echo mine site to conduct an aerial photography survey. He heard WBK operating about 1-1.5 km away and broadcast on the area frequency advising his intention to conduct unmanned aerial photography operations but did not receive a response. He asked the mine manager to contact the farmer and notify the pilot of WBK.

The UAV operator then commenced the flight at about 390 ft above ground level (AGL).

After completing the first load of fertilizer, the farmer informed the pilot of WBK there would be an ‘aircraft’ conducting aerial photography over the Echo mine site. The pilot assumed this would be a fixed-wing aircraft operating at or above 500 ft AGL, and intended to remain at or below 350 ft AGL to ensure separation.

At about 1000, the UAV operator heard WBK and observed the aircraft conduct a turn about 150 m north of the UAV, before it departed to the north. The operator immediately put the UAV into a holding pattern to maintain its current position. He estimated WBK was at about 100-150 ft AGL and came within about 100 m horizontally of the UAV. He attempted to contact the pilot of WBK on the radio but did not receive a response.

The pilot of WBK reported operating at about 50-100 ft AGL on a block just north of the mine site and did not see the UAV.

This incident highlights the challenges associated with having a diverse mix of aircraft operating in the same airspace and the need for all pilots and operators to remain vigilant and employ see-and-avoid principles.

Aviation Short Investigation Bulletin Issue - 27

Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.

On 5 July 2013, the ATSB commenced an investigation into an airspace related event involving a Cessna 208B, registered VH-WZJ, and an unknown aircraft, later identified as VH-BSL, a Pilatus Britten-Norman BN2A-20 aircraft, at Horn Island, Queensland on 31 May 2013.

Examination of the voice recordings collected during the investigation indicated that the pilots of both aircraft had made broadcasts on the common traffic advisory frequency (CTAF). Furthermore, the pilot of VH-BSL indicated that he was holding short on runway 08, to allow VH-WZJ to land on the cross runway (14).

Accordingly, the ATSB decided that there was limited potential to enhance transport safety by continuing this investigation, and has elected to discontinue it.