Runway incursion

What happened

On 17 August 2016, at about 0926 Central Standard Time (CST), an Alliance Airlines Fokker F27 MK 50 aircraft (Fokker 50), registered VH-FKV (FKV), and operating with callsign ‘Unity 3201’, landed on runway 12 at Adelaide Airport, South Australia (SA) after a flight from Olympic Dam, SA. The flight crew consisted of a captain seated in the left seat and a check captain seated in the right seat acting as the first officer. Also on board were two cabin crewmembers and 49 passengers.

Air traffic control (ATC) audio recordings showed that at 0926:53, after FKV had rolled through the intersection with runway 23, the aerodrome controller (ADC) cleared an aircraft for take-off on runway 23 (Figure 1).

Figure 1: Adelaide Airport

Source: Airservices Australia – annotated by ATSB

At the end of runway 12, FKV then exited runway 12 onto taxiway D2. After vacating the runway, the check captain switched the aircraft radio from the ATC Tower frequency to Ground frequency and reconfigured the aircraft in accordance with standard operating procedures after landing. The check captain was unable to immediately contact the surface movement controller (SMC) due to congestion on the Ground frequency. The SMC position had combined SMC and airways clearance^[1] delivery responsibility.

At 0927:46, the ADC cleared a Jetstar Airbus A320 aircraft, registered VH-VGI (VGI), to land on runway 23. At that stage, the ADC sighted the A320 about 3 NM away on final approach. The flight crew of FKV did not hear that clearance.

Shortly after entering taxiway D2, the check captain, seated on the right of FKV looked outside and sighted an aircraft in the take-off roll on runway 23 and also sighted the A320 on final approach. They estimated that the A320 was 5 to 6 NM away. Based on that estimate, the check captain assessed that they would probably be cleared to cross runway 23 behind the departing aircraft and in front of the landing A320, and then turned their attention inside the cockpit to complete their after-landing checks.

As FKV approached holding point D2, the flight crew had not received an ATC clearance to cross runway 23, and the flight crew therefore assumed they were going to stop at the holding point. The check captain was still waiting for a break in transmissions to make their initial contact with the SMC to advise ‘Adelaide Ground, Unity 3201 for bay 50 golf’.

The SMC was issuing a clearance to another aircraft when they sighted FKV taxiing on taxiway D2 towards the direction the controller was facing. At 0927:49, the SMC told the flight crew of an aircraft awaiting an airways clearance to standby, then immediately said ‘Unity 3201 hold short of runway 23, I’ve got you going to 50 golf’.

The check captain of FKV reported that the start of the transmission from the SMC was over-transmitted and what they heard was ‘runway 23 and I’ve got you for bay 50 golf’. As the instruction included the parking bay, the check captain thought the SMC had instructed them to ‘cross runway 23…’ and read back ‘cross runway 23 to 50 golf, Unity 3201’. The SMC thought the pilot read back ‘short runway 23...’ and assumed that the word ‘hold’ had been ‘clipped’. Both flight crewmembers of FKV thought they had received a clearance to cross runway 23.

The ADC sighted FKV on taxiway D2 and heard the SMC say ‘hold short’, but did not hear the response from the flight crew. The ADC scanned runway 23 to check it was still clear for the landing A320, which was then over buildings and less than 30 seconds from touchdown, and then commenced a handover of the ADC position to another controller.

At 0928:10, the SMC coordinated^[2] with the ADC and cleared a vehicle to cross runway 12.

The captain (in the left seat) of FKV then looked to their left and stated ‘clear left’ and taxied the aircraft onto runway 23 to cross. The check captain then looked to their right and sighted the A320 and reported that it was a lot closer than they had expected.

The SMC had looked down at their screen to check the flight strip for the aircraft awaiting a clearance. As the controller looked up, they saw FKV crossing the holding point.

At 0928:21, the SMC called ‘hold short’ and immediately realising that was not the correct instruction, said ‘Unity expedite expedite Unity’. The SMC could then see the A320 in the go-around. The ADC heard the SMC call ‘expedite’ and looked up to see the A320 about 100 ft above the runway – already in the go-around. At 0928:25, the ADC directed the A320 crew to go around.

The captain of FKV continued to taxi the aircraft across the runway and onto taxiway D1 and did not sight the A320 at any time. The A320 (VGI) returned to land without further incident.

Flight crew (FKV) comments

Check captain acting as first officer

The check captain commented that a crossing instruction fitted with their judgment of the situation when they first sighted the A320 while taxiing on D2. They were close to the holding point when they received the initial (hold short) instruction from ATC, and assessed that there was a level of urgency in the SMC’s voice which indicated to them that it was a crossing instruction.

The sun was behind the A320 on final approach to runway 23, which may have affected the check captain’s initial estimate, when they first entered taxiway D2, of how far away the A320 was. However, it was not a factor when FKV taxied onto the runway. At that time, the check captain estimated that the A320 was about 1.5 NM away at about 200 ft above the runway. The check captain decided not to advise the left-seat captain then of the A320 as they had already entered the runway.

There was no confusion in the flight deck over whether they had been instructed to cross the runway or not, they both thought that was the clearance.

The clearance was clipped or over-transmitted and led them to believe it was ‘cross’ not ‘hold short’. In hindsight, the pilot commented that maybe they should have reconfirmed the clearance to cross because the words were clipped, but they expected the readback would give the SMC confirmation that what they understood was correct and the opportunity to detect any misunderstanding. They did not hear anything that sounded like ‘hold short’. It was possible that the check captain had pushed their transmit (push-to-talk (PTT)) button which had momentarily over-transmitted the SMC’s call.

If the check captain had sighted the A320 later in the taxi and closer to the holding point, they would probably have expected to hold short rather than cross in front of it.

The controller’s addition of the bay information to the instruction was not consistent with a hold short instruction. The standard clearance is either hold short (with no further instructions), or cross and taxi to your bay or with additional taxiing instructions.

It was possibly a professional courtesy so the pilot did not have to respond with their bay number, but it added to their expectation that it was a crossing instruction. The flight crew had contacted their company personnel about 100 NM prior to their arrival and were issued with parking bay 50G. It was standard procedure to advise the SMC of their bay number on first contact with the SMC. The SMC presumably gets the bay allocation from the airport ground personnel, and provided that information to the flight crew to save a radio transmission. However, its addition to the end of the hold short instruction misled the pilots.

In the absence of any communication with the SMC prior to reaching the holding point, they would have stopped at the holding point rather than enter the runway.

When discussing the incident afterwards, the captain told the check captain that they had not been aware of or sighted the A320 at any time. The check captain commented that maybe they should have told the captain ‘there is one rolling and one on final’ when they first saw the two aircraft to increase the captain’s situational awareness.

Captain

The captain was normally based in New Zealand and commented that to cross an active runway there, pilots are required to contact the ADC on the Tower frequency for a clearance.

The captain was intending to stop at the holding point, but proceeded to cross when they thought they got the clearance to do so. They had to increase power to accelerate, having slowed ready to stop.

The bay number was a non-normal addition to a taxi instruction, possibly provided as the check captain had not yet been able to give the normal transmission with their bay allocation after exiting the runway.

Controller comments

The air traffic controllers provided the following comments.

Aerodrome controller

It was a quiet and routine traffic sequence and the weather at the time was benign.

The voice equipment was fitted in 2013 to Adelaide Tower. The Tower was a ‘quiet tower’, which means that the controllers can only hear the transmissions on the frequency they are controlling, in their own headsets. Although the ADC could hear the SMC give the instruction to hold short, they could not hear any response from flight crew on the Ground frequency.

Prior to the implementation of the quiet tower, controllers could hear transmissions on the other frequencies on speakers in the Tower. The ADC commented that this improved their situational awareness, particularly from a coordination perspective.

The ADC commented that since the incident, in a similar situation, they would wait for the aircraft to land before commencing a handover.

The ADC commented that following the incident there would be a greater focus among the controllers, not just on the instructions controllers give, but that it is not complete until you get adequate readback that responds to all the components of the clearance. In addition, there should be no taxi instruction beyond a hold short instruction.

Controller taking over from aerodrome controller

The controller in the process of a handover/takeover with the ADC was looking at the weather display and listening to the ADC handing over, when they heard the SMC say ‘hold short’ and then ‘expedite’. The controller looked across and sighted FKV half way across the runway and the A320 in the go-around.

The controller commented that before the ‘quiet tower’ they could all hear each other’s radio, which improved their situational awareness.

The controller also commented that when they receive a call from a pilot, they sometimes miss the first part of the transmission. The controller reported that this is a known fault that the controllers have reported via the Airways systems issues reporting scheme (see below). They also advised that they have become desensitised to hearing only part of the readback, which negates the effectiveness of the readback.

The controller advised that there were a number of things that could have prevented the incident:

• if the SMC had heard the readback correctly
• better scanning by air traffic controllers and pilots of aircraft approaching and crossing runways
• stop bars^[3] could have been an effective risk control even without hearing the readback or effective scanning.

The controller commended the actions of the A320 flight crew.

Surface movement controller

The SMC was confident they had given the hold short instruction clearly.

The SMC thought that the Unity flight crew would be expecting to hold short because there was no way they were going to be cleared to cross in front of the landing A320. The SMC commented that if they had not contacted Unity 3201 as they were approaching the holding point, they would have stopped. Because the aircraft was taxiing towards the runway and it is difficult to tell if the aircraft is slowing down, the SMC issued the hold short instruction to be sure they would stop.

They commented that they added the bay number to the hold short instruction to save a transmission, as another aircraft was waiting for their clearance. They were not sure why they did not pick up the incorrect readback, but they did not hear the first word.

The SMC asserted that in most of the transmissions in Adelaide, the initial second of a readback is clipped, for example they only hear ‘short’ instead of ‘hold short’. The controller thought the readback was ‘short runway 23’ not ‘cross runway 23’. As they thought the pilot would be expecting to hold short, the controller was expecting the readback to be ‘hold short’ and that expectation affected what the controller heard.

In Adelaide Tower, it is difficult to tell when a controller’s PTT button is released and whether the frequency is open or closed. Normally for a ‘hold short’ readback, you would be expecting two words but they get used to looking for one word. If you are not certain of a readback, you are meant to ask again, but if they don’t get the first word every time, it can lead to a lot of additional transmissions. Maybe if radio operators push the PTT button and then wait two heartbeats before they start talking, that technique may prevent transmissions being clipped.

The pilots may not hear the controllers’ instructions clearly either as they are also not listening in a perfect environment.

The airport ground staff provide the ADC with bay allocations, which the ADC then put on the flight strip. When the pilots first make contact with the SMC, they state the bay allocated by their company and the SMC checks that matches the bay number on the strip.

The SMC did not hear the ADC clear the A320 to land (or the other aircraft to take off) because they were issuing a clearance at the time.

If the A320 had landed and FKV had crossed the runway, they may have just got across in front of it but it would have been close.

If the airport had stop bar lights, the incident would more than likely not have occurred.

Manual of air traffic services

In the Manual of air traffic services (MATS), under section 12.3.1.11 Taxiing across runways, section 12.3.1.11.1 Intermediate holding points, stated: ‘Do not include positions beyond required intermediate holding points in taxi instructions.’

Airways systems issues database report

Airservices Australia provided the ATSB with a copy of the relevant Airways systems issues database (ASID) report. In June 2013, the ASID report from Adelaide ATC stated that inbound calls from pilots were clipped at the beginning of calls. This could be heard on recorded audio from the tower transmissions and was compared with transmissions recorded prior to the implementation of the new radio system. Following ATC transmissions, when the controller releases the PTT, the voice communications control system switch remains in the transmit state for 200 milliseconds, known as the guard period. During this period, receive audio is blocked, therefore the audio from pilots is dropped.

In August 2014, the report was updated to state that the clipping issue had been incorporated into the voice system training manual. On 17 December 2015, the comment added was ‘Vendor has advised that this defect will be addressed in the next software release which is currently scheduled for delivery in June 2016’. There was no indication what, if anything, was delivered in that release to address the issue.

On 25 August 2016, a comment was added to the report indicating that rather than a system defect, the cut-off responses could be ‘mostly attributed to poor radio technique by pilots or ATC’. Furthermore, ‘it is also important that controllers release PTT as soon as possible to ensure that the receiver is unmuted’.

The ASID entry dated 17 December 2015 was based on information received from the vendor. Airservices sought input from the vendor on whether they believed the reported issue was a defect and whether the guard period could be adjusted.

Airservices received a response from the vendor with a list of issues which the vendor aimed to address in the next release and the guard period issue was included in this list. Airservices has investigated this issue and has determined it is not a system issue, given that the guard period of 200 milliseconds is less than other voice communication systems used by Airservices and the same as used in other Integrated Tower Automation Suite (INTAS) towers where there has been no observed replication of this issue. It was instead concluded that this issue was due to controller actions related to extended engagement of the foot PTT beyond the end of their transmissions. Airservices considers that the issue was not prevalent in the occurrence as was communicated by the interviewees.

Airservices Australia comment

Airservices Australia provided the following comments in response to the ATSB draft report.

Quiet tower

Although some controllers prefer speakers to increase their situational awareness, it may also result in considerable noise when all three positions are open during periods of increased traffic. Such noise is particularly distracting for controllers that have transitioned from an enroute environment where headsets are used and speakers are not permitted.

Additionally, ATC procedures are designed to ensure controllers can perform their duties safely without reliance on speakers. The use of speakers does not always increase situational awareness and should not be relied upon as an effective threat barrier.

Clipped transmissions

The recorded audio leading up to, during and after the occurrence did not contain any clipped transmissions related to the ‘fault’ reported.

Adelaide Tower Line Manager's and Shift Manager's regular monitoring of the controller's air­ ground communications have observed that pilot transmissions may occasionally be missing the first part of the call (clipped transmissions are less than one second in duration). This typically occurs when the pilot commences their response prior to the controller releasing the press to talk (PTT) button. However, clipping of this nature does not occur frequently and not to a point where controllers would become desensitised to only hearing part of the readback.

Existing ATC procedures require the controller to obtain a correct readback of instructions (in accordance with per AIP GEN 3.4 -12). In the absence of the correct and complete readback, the controller must challenge the readback until they are satisfied it is correct.

Audio sample

Airservices randomly sampled 90 minutes of audio from 1 August 2016 at Adelaide and did not identify any calls which had a clipped the transmission.

On 12 September, Airservices reviewed the radio technique of a controller in the tower using a foot PTT and noted that there was a significant (0.5-1 second) delay from the end of the delivery of the instruction by the controller to the time when the controller disengaged the foot PTT. This anomaly in the controller's technique resulted in a number of clipped pilot transmissions due to them starting the readback whilst the foot PTT was still engaged. The controller's error was rectified by using the in-line PTT which decreased the delay of the controller releasing the foot PTT.

Additionally, the Voice Communications and Control System (VCCS) enables controllers to view the status of the transmitter and receiver.

ATSB comment

The A320 crew are to be commended for their actions in preventing a potentially more serious incident occurring.

The flight crew of FKV thought they were cleared to cross the runway probably because of the bay allocation at the end of the hold short instruction. An effective sighting of the aircraft on final approach may have led them to query their understood instruction to cross the runway.

The SMC heard one word in response and mis-heard it as ‘short’ rather than ‘cross’ and that assumed ‘hold’ had been clipped from the transmission. The SMC did not question the pilots about the missing word as they had some previous experiences of the beginning of transmissions being clipped. As there was a ‘quiet tower’ communications system, there was no opportunity for the ADC to hear this pilot read-back to the SMC and notice the misunderstandings before the runway incursion.

The ADC was in the process of handover/takeover and was not watching the landing A320 or the runway as they assumed FKV would hold short and that the runway was clear.

Safety message

The risk of runway incursions and other separation events can be minimised through good communication. This incident highlights the importance of:

• controllers and flight crews using correct phraseology
• controllers and pilots challenging instructions which they have not heard or understood fully
• pilots looking carefully for aircraft or other hazards before entering an active runway.

Aviation Short Investigations Bulletin - Issue 54

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 2016 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 clearance issued by ATC to operate in controller airspace along a designated track or route at a specified level to a specified point or flight-planned destination.
2. Coordination is the process of obtaining agreement on clearances, transfer of control, advice or information to be issued to aircraft, by means of information exchanged.
3. Stop bars are a series of unidirectional lights at right angles to the taxiway centreline. The lights are spaced three metres apart and located 0.3 m before the holding point. Stop bars show red in the direction of approach to the stop bar from the taxiway and are controlled by ATC.

What happened

At about 0738 Central Standard Time (CST), a Cessna 172 aircraft, registered VH-EKV (EKV), taxied to depart from runway 12 at Alice Springs Airport, Northern Territory for Ayers Rock. The pilot and two passengers were on board the private flight. The air traffic control Tower was scheduled to open at 0800. At the time of departure, procedures for operating in the vicinity of non-controlled aerodromes applied at Alice Springs Airport. The airport has a common traffic advisory frequency (CTAF) when the Tower is closed.

The aircraft was located on the general aviation apron and taxied for holding point bravo for runway 12 (yellow line in Figure 1). The pilot of EKV broadcast a taxi call on the CTAF.

Figure 1: Alice Springs Airport showing the taxi routes and relevant locations of EKV (yellow line) and MLB (orange line)

Source: Google earth, modified by the ATSB

The transcripts of the relevant CTAF recordings are shown below, with the time, who made the broadcast, the transmission, and readability.^[1]

Following the broadcast by the pilot of EKV, several broadcasts were made on the CTAF where the airport rescue and firefighting service were conducting routine radio checks.

At 0741:15, the pilot of a Beech 58 aircraft, registered VH-MLB (MLB), broadcast a taxi call on the CTAF (the readability was 2, as the call was badly broken and very hard to understand). The aircraft was located on the commuter apron and taxied for holding point echo with the intention of then backtracking on the runway in preparation for a runway 30 departure (for a flight to Nyirripi) (orange line in Figure 1). The pilot and two passengers were on board the charter flight.

 At 0741:25, the pilot of EKV broadcast that they were lining up on runway 12 (Figure 1).

 The pilot of MLB reported that they did not hear this broadcast from EKV, nor the earlier broadcast that they were taxiing for runway 12.

At 0741:30, the pilot of a Piper PA32 broadcast a taxi call (the readability was 3, with a loud squeal). The PA32 was located at the general aviation apron, close to where EKV had taxied earlier, and was taxiing for runway 12.

 The pilot of MLB responded to the broadcast by the pilot of the PA32, asking if they were happy for MLB to taxi (which included entering and backtracking the runway) for runway 30, and advised that they were ‘shortly to depart’.

 The pilot of the PA32 responded to that broadcast by indicating that they would hold short of runway 12.

 The pilot of MLB responded, thanking the pilot of the PA32.

 Following this exchange between the pilot of the PA32 and the pilot of MLB, several broadcasts were made on the CTAF, where the airport fire and rescue service were conducting radio checks (at 0741:53, 0741:59, and 0742:02).

The pilot of MLB approached holding point echo and reported looking for other aircraft on approach or lined up on either runway (12 or 30). The pilot of MLB did not see any other aircraft and had not heard any other aircraft on the CTAF except for the PA32, so entered the runway and commenced backtracking runway 30 (orange line in Figure 1).

At about the same time, the pilot of EKV commenced take-off on runway 12. At about take-off speed, the pilot reported observing another aircraft enter the runway and start taxiing on runway 12 (away from them). The pilot assessed that it would be more dangerous to stop, so continued with the take-off.

An air traffic controller arrived in the control tower (which was due to open at 0800) and observed a Cessna 172 aircraft (EKV) taking off on runway 12 and a Beech 58 aircraft (MLB) taxiing on the same runway, about half way down the runway (Figure 1). The controller advised the pilot of EKV to stop immediately.

The pilot of EKV reported not hearing the advice to stop immediately, but was busy with the take-off. The controller reported that EKV was airborne approximately 500 m before the position of MLB and passed overhead MLB at about 150 feet above ground level. The pilot reported banking the aircraft to the north at about 500 feet and two-thirds of the way down the length of the runway to avoid any possible conflict with the aircraft (MLB) on the runway.

The pilot of MLB heard the controller’s advice to another aircraft to stop, but was not aware of the reason. During the turn at the end of the runway to line up on runway 30, the pilot noticed a Cessna 172 (EKV) in a left turn toward the north. The pilot broadcast on the CTAF for the aircraft in the Alice Springs circuit area to notify their intentions.

 The pilot of EKV then gave a departure call at 0744:14 (readability was 4).

 The pilot of MLB believed that the pilot of the Cessna 172 (EKV) had responded to their broadcast, and reported that the readability from the Cessna 172 was very poor. The pilot of MLB responded to the Cessna 172 at 0744:27, but that broadcast was over-transmitted by another aircraft making a taxi broadcast.

The next broadcast recorded from MLB was at 0747:19, where the pilot broadcast a departure call. The pilot reported having made lining-up and holding broadcasts, which may have been over-transmitted, and also making a rolling broadcast that was not recorded on the CTAF.

Both aircraft departed without further incident.

Pilot comment VH-EKV

The pilot reported generally operating at Alice Springs Airport when the tower was open, so would normally communicate with the tower controller. At the time of the occurrence, the Tower had not opened and the pilot reported hearing radio calls, but commented that radio calls from aircraft were not as clear as those made from the tower controllers. The pilot was aware that there was another aircraft departing to Nyirripi (destination of MLB).

Pilot comment VH-MLB

The pilot reported identifying the location of the PA32 as they approached holding point echo. The pilot commented that there were some white buildings in the distance behind the threshold of runway 12 that may have made it difficult to see EKV. The pilot indicated that the runway, although long, it is quite flat, and the whole runway was visible. The pilot also indicated that they were focused on known traffic. The pilot recognised the aircraft registration of the PA32 and the voice of the pilot, and confirmed the location of that aircraft before entering the runway.

The pilot reported that the winds were calm. They elected to use runway 30 as it was the most convenient runway for their departure.

Radio communication - Alice Springs airport

A study was conducted in 2010 by the Civil Aviation Safety Authority (CASA) to review the airspace classification above Alice Springs, Aeronautical Study of Alice Springs (YBAS) January 2010, and is available from the CASA website. The study consulted with stakeholders and did not identify any radio transmission ‘black spots’.

ATSB comment

The relevant communication recordings for the Alice Springs CTAF were obtained by the ATSB from Airservices Australia and the relevant broadcasts were given a readability level by the ATSB using the standard in radiotelephony communications as published in the AIP. The communications recorded are not necessarily what a pilot hears in their respective aircraft.

The ATSB could not establish why the pilots of both aircraft did not hear the broadcasts from the other aircraft.

Safety message

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One such concern is Safety around non-controlled aerodromes, which highlights that it is difficult for pilots to detect another aircraft through visual observation alone. The ATSB has identified that insufficient communication between pilots operating in the same area is the most common cause of safety incidents near non-controlled aerodromes.

This incident highlights the fundamental importance of effective communication, particularly during operations at a non-controlled aerodrome. The Civil Aviation Safety Authority (CASA) has produced several publications and resources that provide important safety advice related to operations in the vicinity of non-controlled aerodromes. Relevant guidance and explanatory material provided by CASA includes the following:

• CASA Civil Aviation Advisory Publication (CAAP) CAAP 166-1(3) Operations in the vicinity of 
  non-controlled aerodromes, 
• CAAP 166-2(1) Pilots’ responsibility for collision avoidance in the vicinity of non-controlled aerodromes using ‘see-and-avoid’,
• Operations at non-towered aerodromes booklet.

Aviation Short Investigations Bulletin - Issue 53

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 2016 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]     As outlined in the Airservices aeronautical information publication (AIP), the readability scale is as follows: 1. Unreadable, 2. Readable now and then, 3. Readable but with difficulty, 4. Readable, 5. Perfectly readable.

[2]     Alice Springs Airport has an aerodrome frequency response unit (AFRU) installed. The AFRU is to provide an automatic response to CTAF broadcasts to indicate to an operator that the correct radio frequency was selected and to confirm the operation of the radio’s transmitter and receiver, and the volume setting. If a broadcast has not been made on the CTAF in the preceding five minutes, and this transmission is over 2 seconds in length, a voice identification from the ARFU ‘Alice Springs CTAF’ is generated. If a broadcast has been made on the CTAF in the preceding five minutes, a 300-millisecond tone will be generated after each transmission over two seconds long.

What happened

On 7 June 2016, at 0418 Eastern Standard Time (EST), the pilot of a Fairchild SA227-DC, registered VH-HPE (HPE), departed Brisbane Airport, Queensland, for a flight to Mount Isa, Queensland. The flight included intermediate stops at Rockhampton and Richmond. The pilot was the only person on board the scheduled freight flight.

Prior to commencing the flight, the pilot reviewed the weather and NOTAM^[1] information. The pilot noted there was no NOTAM information for Richmond Airport for the expected arrival time.

After completing the first leg of the flight, HPE departed Rockhampton for Richmond 30 minutes later than scheduled, at about 0615. The expected arrival time for Richmond was about 0810.

At about 0800, the aerodrome reporting officer (ARO) arrived at Richmond Airport with a work crew to undertake pre-planned work. The planned work was to remove plant growth from around the runway lights. The ARO conducted a pre-work safety briefing which included the work crew actions in the event of an aircraft arrival. The ARO then gave the two available hand-held VHF radios to the workers in the two works vehicles working within the runway strip. The ARO did not have a VHF radio in their vehicle and they were the only person qualified to broadcast on the common traffic advisory frequency (CTAF) used by aircraft, which uses VHF. All other works vehicles carried UHF radios.

At about the same time, the pilot of HPE broadcast on the Richmond CTAF advising they were 40 NM to the east and conducting a straight-in approach to runway 27. The pilot received a full response from the aerodrome frequency response unit (AFRU).^[2]

After the brief, the workers undertook the required task in three groups. One group positioned at the eastern end of the runway and a second group at the western end of the runway while the ARO remained at a mid-point along the runway (Figure 1). While the work groups conducted the plant removal, the pilot of HPE activated the pilot activated lighting.^[3] The workers in the groups at each end of the runway observed the lights illuminating and immediately began to vacate the runway strip.^[4] The pilot made a further broadcast when 20 NM east of Richmond, and received only a short response from the AFRU.

At about 0815, as the aircraft joined a 5 NM final approach to runway 27, the pilot reported that they sighted a vehicle on the runway threshold moving clear of the runway strip. The pilot then broadcast on the Richmond CTAF and broadcast again passing 3 NM on final approach to the runway. They received no response to the broadcasts apart from the AFRU short response.

As HPE approached the runway, the pilot reported that they noticed vehicles and equipment at the far end of the runway and witches hats along the edge of the bitumen. As the vehicles and equipment had moved clear of the runway strip, the pilot continued the approach. At a height of about 100-200 ft above ground level, the pilot reported that they observed a person inside the runway strip near the bitumen of the runway and conducted a go-around.^[5]

The pilot then re-joined the circuit, and observed that all workers and equipment were clear of the runway. The pilot conducted a second approach and landed without incident.

No persons were injured, and the aircraft was not damaged in the incident.

Figure 1: Richmond Airport 

Source: Google Earth, modified by the ATSB

Aerodrome reporting officer (ARO) comment

The aerodrome reporting officer provided the following comments:

• The works procedures for Richmond Airport require a NOTAM to be provided for all works within the runway strip exceeding 30 minutes duration. As the ARO did not expect the works to exceed 30 minutes duration, no NOTAM was provided.
• The ARO elected to conduct the works on a Tuesday, as no passenger service was scheduled for that day.
• The ARO receives no notification of the actual expected arrival time of the scheduled daily freight service, therefore they were not aware that the service was running late and did not check the airport movement log. Had the ARO checked the log they would have delayed the works until after the aircraft had departed.
• The work crews carried two hand-held VHF radios for communicating with aircraft. While broadcasts from aircraft further than 5 NM from Richmond Airport may not be heard, calls within 5 NM are generally received.
• The runway lights were activated about 15 minutes prior to the aircraft landing.
• HPE conducted a straight-in approach to runway 27. In the past, aircraft arriving overflew the airport prior to approaching to land which the ARO believes is a safer procedure.
• All workers and equipment were clear of the runway strip at the time HPE arrived. However, the workers and equipment positioned themselves just outside the runway strip. It may have appeared to the pilot that the workers and equipment were not clear.

Pilot comment

The pilot of HPE provided the following comments:

• When approaching Richmond Airport an inbound radio broadcast was made. The AFRU provided a full response, which confirmed that their radio was working correctly and no radio broadcasts from other sources had been recently made within the Richmond CTAF.
• No radio call was received from the work crew before or after the incident.

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.

Airport operator

As a result of this occurrence, the airport operator has advised the ATSB that they are taking the following safety action:

Change to works procedure

Prior to conducting works within the runway strip, the flight log is to be reviewed to ensure no flights are scheduled to arrive while work is in progress.

Safety message

The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One identified concern is Safety around non-controlled aerodromes.  

This incident shows the importance of communication and ensuring that the systems exist and are used to minimise the likelihood of communication break downs. Effective communication between all parts of the aviation system, along with robust systems in place to support the individuals, is essential for safe operations.

• The ATSB booklet, A pilot's guide to staying safe in the vicinity of non-controlled aerodromes provides information to assist pilots to safely operate around non-controlled aerodromes.
• The Airservices Australia document An airside driver’s guide to runway safety provides information to assist ground personnel to operate safely at both controlled and non-controlled aerodromes.

Aviation Short Investigations Bulletin - Issue 53

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 2016 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.

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[1]     A Notice To Airmen (NOTAM) advises personnel concerned with flight operations of information concerning the establishment, condition or change in any aeronautical facility, service, procedure, or hazard, the timely knowledge of which is essential to safe flight.

[2]     Aerodrome frequency response unit provides an automatic response when pilots transmit on the traffic frequency for that particular aerodrome. If no other transmissions have been received by the AFRU within the previous 5 minutes the AFRU will respond with a pre-recorded voice message comprising aerodrome identification followed by ‘CTAF’. If a transmission has been received within the previous 5 minutes the AFRU will respond with only a short tone.

[3]     Pilot activated runway and taxiway lighting is activated by a series of timed transmissions using the aircraft’s very high frequency radio, on either a discrete or the local airport communication frequency.

[4]     Runway strip is a prepared area provided around the runway to reduce risk of damage to an aircraft running off of a runway and also provide an obstacle-free area for aircraft using the runway during take-off and landing.

[5]     Go-around, the procedure for discontinuing an approach to land, is a standard manoeuvre performed when a pilot is not completely satisfied that the requirements for a safe landing have been met. This involves the pilot discontinuing the approach to land and may involve gaining altitude before conducting another approach to land.

What happened

On 10 September 2015, at about 0930 Eastern Standard Time (EST), an instructor and student pilot of a Cessna 172M aircraft, registered VH-EJM (EJM), were conducting circuits at Townsville Airport, Queensland.

The student was flying the aircraft and on mid-final for a touch-and-go landing on runway 07, when the instructor noticed a truck on the perimeter road, near the threshold to runway 07. The truck had not held at the stop sign. The stop sign required all vehicles to stop, look for aircraft, and not proceed unless there was no aircraft landing (Figure 1).

Shortly after the instructor sighted the truck, the Townsville Tower air traffic controller advised the pilots of EJM that there was a truck on the perimeter road. The instructor acknowledged the controller and they proceeded with the landing.

The aircraft conducted a touch-and-go and continued with several more circuits without incident.

Figure 1: Townsville airport perimeter road near runway 07

Source: Google earth, modified by the ATSB

Instructor and aircraft operator comments

The instructor commented that another vehicle on the perimeter road, ahead of the truck, also did not stop at the stop sign.

The operator reported this could potentially have been a more serious issue if the student pilot was conducting their first solo flight, as there would be greater risk that the student might get low on the approach and might not see the truck.

Department of Defence investigation

The Department of Defence conducted an investigation into the serious incident. They determined that a contractor, driving a truck on the western perimeter road, failed to stop at the stop sign near the threshold of runway 07. VH-EJM missed the top of the truck by about 4 to 5 metres and the aircraft landed without incident.

The Department of Defence also conducted a subsequent investigation into an incident where a contractor driving a truck on the western perimeter road failed to stop at the stop sign near the threshold of runway 07. The pilot of a Cessna C172RG aircraft that was on short final, saw the truck coming towards their approach path and informed air traffic control. Air traffic control acknowledged the transmission. The truck stopped almost directly under the path of the arriving aircraft and the aircraft landed without incident.

The investigation determined that the stop signs located on the perimeter road on approach to runway 07 provided drivers with clear direction to stop, observe and give way to approaching aircraft. The failure of the drivers of the vehicles in these incidents to observe those protocols created the potential for a collision between the vehicle and the aircraft.

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.

Department of Defence

As a result of this occurrence, the airport operator has advised the ATSB that they are taking the following safety actions:

• briefing material for contractors has been updated placing greater emphasis on safety around runways.
• flashing lights have been installed on the stop signs, for the under-run service road, to improve observation of the sign by drivers.

ATSB comment

At the time of writing this report, two other similar events occurred on 8 and 10 December 2015. The occurrences were subsequent to the update of briefing material for contractors and the installation of flashing lights on the stop signs. The Department of Defence are conducting a review of their safety actions to see if there are any other options to prevent a re-occurrence.

Safety message

The International Civil Aviation Organization (ICAO) has identified runway safety as one of its priorities and has been working with countries and aviation organisations globally to reduce runway safety accidents. ICAO has developed a runway safety website, which offers a range of information and products to assist the aviation community to improve runway safety.

In addition, ICAO has published a Manual on the Prevention of Runway Incursions Doc 9870 AN/463, available from the ICAO website. The manual includes information on the prevention of runway incursions. The manual discusses that deficiencies in design, training, technology, procedures, regulations and human performance can result in a system break down and safety being compromised. A pilot, as part of the last line of defence, cannot assume that anyone will do the right thing, like the driver of the truck stopping at the stop sign, and they need to be prepared to re-evaluate the planned flight.

Additional information on runway safety is also available from the Airservices Australia webpage Runway safety.

In addition, Airservices Australia has published a guide for airside drivers, The Airside Drivers Guide to Runway Safety, which focuses on four aspects of operating safely on an aerodrome:

1. planning your aerodrome operation
2. aerodrome procedures
3. communications
4. aerodrome markings, signs and lights.

Aviation Short Investigations Bulletin Issue 46

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 2016 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.

Circumstances

At 0341 hours the driver of Qantas tug Red Charlie requested permission to tow a Qantas B767 aircraft from the Qantas Maintenance Area to the International Terminal Bay 30. The driver was cleared by ATC to tow the aircraft via taxiway foxtrot and hold short of runway 16. This instruction was acknowledged by the driver.

VH-AMB was arriving at Sydney on a flight from Armidale and was on final approach to runway 16.

As the tug approached the holding point for runway 16 the Aerodrome Controller [ADC] issued the hold short instruction a second time which was again acknowledged by the driver. The ADC had decided that VH-AMB would land before the tug would be given permission to cross runway 16 and issued a landing clearance to that aircraft at 0345 hours.

It had been common practice during the night shift, for tug drivers to receive a clearance to cross runway 16 at the point at which the ADC issued the second hold short instruction. With this expectancy in mind, the tug driver thought he had received a clearance to cross runway 16 when he acknowledged the second hold short instruction.

The holding point for runway 16 on taxiway foxtrot is not easily recognised from the tower at night and controllers therefore had to rely on pilots/drivers complying with any instruction received. As Red Charlie was approaching this holding point, it was not possible for the ADC to accurately determine the position of the tug and aircraft.

At 0346.10 hours the pilot of VH-AMB informed the tower that he had an aircraft in front of him on the runway. The ADC immediately cancelled the landing clearance and established that Red Charlie was clear of runway 16, having crossed that runway. As VH-AMB was still in a position to land, a second landing clearance was issued at 0346.55 hours.

VH-AMB continued the approach and landed safely.

Significant Factors

1. The driver of Red Charlie had an expectation that he would be given a clearance to cross runway 16 at the time the second hold short instruction was issued.

2. The position of the taxiway foxtrot holding point is difficult to visually judge at night from the control tower. 3. The driver of Red Charlie did not read back the instruction to hold short of runway 16. 4. There is no ATC requirement for the read back referred to in 3 above.

Safety Actions

The Bureau of Air Safety Investigation issued a Safety Advisory Notice [SAN930310] to Qantas Airways, the Civil Aviation Authority and the Federal Airports Corporation. It stated that:

The Bureau of Air Safety Investigation advises that formal radio procedures instruction should be included in all airside driver training and suggests that ATC could have an input into such training.

Simultaneous runway operations were being conducted at the time of the occurrence with departures from runway 16 and arrivals on runways 16 and 07. A busy traffic situation was creating high workload levels for the tower staff. Weather conditions were fine with light winds.

The air traffic situation around the airport was further complicated by an overflying helicopter which had departed from Prince Henry hospital, located 8 km to the east, enroute to Bankstown via overhead Sydney Airport at 1,500 feet.

VH-AJM taxied at 0744 EST and at 0747, reported ready for take-off on runway 16, from the intersection with taxiway Foxtrot, 536 metres south of the runway 16 threshold. VH-MZM taxied at 0750 and was instructed to taxy to and hold at the holding point adjacent to the threshold of runway 16. The planned departure sequence from runway 16 was VH-AJM followed by VH-MZM.

The Tower Controller amended the departure sequence due to the presence of the overflying helicopter, as the departure track of VH-AJM placed that aircraft in potential confliction with the helicopter. He decided that VH-MZM should take-off before VH-AJM.

When VH-MZM was instructed to line up, the crew of VH-AJM mistakenly believed the instruction was addressed to them and commenced to taxy beyond the holding point into the runway strip. They recognised their error when VH-MZM was subsequently cleared for take-off. Although the Tower Controller had not observed VH-AJM move beyond the holding point, as his view of taxiway Foxtrot was obscured by a structural roof support beam, the incursion was immediately noticed by the Tower Coordinator and the Surface Movement Controller who alerted the Tower Controller.

The take-off clearance for VH-MZM was cancelled and both aircraft were instructed to vacate the runway to allow an aircraft on final approach for runway 16 to land.

Significant Factors

1. The crew of VH-AJM expected to depart before VH-MZM.

2. The Tower Controller amended the departure sequence due to overflying traffic in potential conflict with the departure track of VH-AJM.

3. The crew of VH-AJM misinterpreted the callsign when the Tower Controller issued a line up clearance to VH-MZM.

The Partenavia was being flown from Essendon to Sydney. During the final stage of the flight the aircraft was radar vectored for an approach and landing on runway 34, which was accomplished normally.

After landing, the aircraft vacated left into taxiway 'Alpha' and contacted Surface Movement Control (SMC), which cleared the aircraft to cross runway 34 via taxiway 'Hotel' and hold short of runway 07. Although this was acknowledged by the pilot, the aircraft continued past the holding point on taxiway 'Charlie' and infringed the runway 07 flight strip, despite being queried by SMC. When the pilot of the Partenavia recognised the aircraft had entered the flight strip he immediately carried out a 180 degree turn to vacate, during which the runway surface itself was slightly infringed.

In the meantime, a Boeing 737, VH-TJO, which had been cleared to take-off on runway 07, was instructed by the Aerodrome Controller (ADC) to stop immediately. This was accomplished safely from a reported speed of 100 knots. The aircraft was able to vacate the runway via taxiway 'Charlie'.

The pilot of VH-MGZ was instructed to taxi for runway 30 and to hold short of runway 35. The aircraft was later observed approaching the holding point and taxiing at a considerable speed. The pilot was instructed to stop immediately. The aircraft came to a halt just within the flight strip of runway 35. VH-CSN was sent around from short final approach. The pilot reported that he had been distracted by his preparation for a navigation exercise and by the two passengers on board his aircraft.

The pilot of FDP had been instructed to taxy to the holding point at taxiway A2 for departure. The Surface Movement Controller then diverted his attention to other traffic. The Aerodrome Controller then noticed that FDP was holding at the intersection of runway 15 and taxiway A3 , partially inside the holding point.

The pilot advised that the aircraft was slightly inside the holding point and asked for approval to conduct engine checks in that position. As there was no immediate traffic, the aircraft was cleared onto the runway. The pilot reported that he did not see the holding point marking until he had passed over it. He added that the marking did not extend across the full width of the taxiway, and felt that this contributed to the incident. In addition, he had not operated into Cairns for more than 2 years, so he was not completely familiar with the aerodrome layout.

The comments by the pilot on the holding point marking were discussed with the local Airservices manager and the airport owner. Both these agencies indicated that there had been other instances of pilot confusion concerning taxiway markings in the same area. It was agreed that Airservices would arrange for a 'Caution' note to be inserted in the En-route Supplement advising pilots to exercise caution when approaching the taxiway A3 holding point. The airport owner was completing arrangements to repaint the holding point marking to extend the full width of the taxiway, and to repaint the holding point and frequency information on the associated gable marker.

Prior to issuing a take-off clearance the controller checked that the runway was clear. Take-off was rejected when the crew of VH-OGK saw a vehicle on a taxiway and entering the runway. The aircraft exited via the next available taxiway and returned to the runway end for an uneventful departure.

A pest control contractor had been escorted to an aircraft parking area on the domestic apron to fumigate a number of aircraft. He was also informed that another aircraft to be treated was in the maintenance hangar on the other side of the airport. He indicated that he would travel to the hangar via the public roads outside the airport and that he would leave the airport via Gate 1, through which he had entered. He also indicated that he knew the location of the airline's operations office. No airline supervision was provided while the contractor did his work.

On completion of the work on the apron the contractor decided to travel to the hangar via the perimeter road inside the airport. He ultimately arrived at the hangar and completed the task there. No supervision was provided by hangar staff as they were not aware the contractor did not have an airside licence. The contractor departed the hangar intending to return to gate 1 via the perimeter road. While driving along the taxiway from the hangar he missed the turn to the perimeter road and crossed the holding point to the runway. This was when the aircraft crew observed the vehicle and rejected the take-off. A short time later, the vehicle was intercepted by an airport safety officer.

Procedures required that all persons who do not hold an 'Airside Drives Authority' be escorted and supervised at all times while airside. This requirement was not complied with in this instance. As an additional safety measure, a 'Safety Information Note' has been prepared for issue to all airside visitors.