Investigation summary

What happened

On 18 June 2025, a Beechcraft King Air B200, registered VH-EEL, was on descent into Bankstown Airport, New South Wales, on a passenger transport flight with the pilot and 4 passengers on board when the pilot heard a whistling noise followed by the sound of an impact coming from the rear of the aircraft. There were no abnormal indications and the aircraft was flying normally, so the pilot continued the flight.

Shortly after, the pilot was unable to reach air traffic control via radio and switched to the aircraft’s alternative radio. Communication was re‑established and the aircraft landed safely. An external inspection of the aircraft found that the VHF antenna on top of the fuselage was missing, and the vertical stabiliser was damaged.

What the ATSB found

While the top of the antenna was not recovered, the aluminium antenna base showed evidence of moisture ingress. This resulted in the antenna failing and separating from the aircraft. The exact failure mechanism could not be determined – moisture could have been absorbed by the composite skin of the antenna, reducing its strength. Alternatively, observed corrosion could have weakened the bond between structural components within the antenna, reducing stiffness and allowing cracks to develop.

Safety message

While it is not clear whether pre-existing damage was observable during antenna inspections, this occurrence is a useful reminder on the importance of vigilance while conducting routine maintenance. In addition, it serves to demonstrate the value of redundancy in safety-critical systems.

The investigation

The occurrence

On the afternoon of 18 June 2025, a Beechcraft King Air B200, registered VH-EEL, departed from Dubbo Airport, New South Wales, on a passenger transport flight to Bankstown Airport. The flight was operated by CJ Aerospace with the pilot and 4 passengers on board. It was a clear day and the aircraft was flying in visual meteorological conditions. 

At approximately 1523, the aircraft was about 30 NM (55 km) from Bankstown Airport and descending through 11,000 ft when the pilot heard a whistling noise coming from the back of the aircraft. After a few seconds, the pilot reported hearing the sound of an impact towards the rear of the aircraft. The aircraft’s airspeed was approximately 280 kt at the time. There were no abnormal indications in the cockpit and the aircraft was flying normally, so the pilot continued with the flight.

The aircraft had been previously cleared by air traffic control (ATC) to descend to 5,000 ft. However, after reaching this altitude it had not been cleared for further descent, which the pilot noted to be unusual. The pilot conducted a radio check with ATC but received no response. The pilot switched the aircraft’s active VHF radio from COM 1 to COM 2, and contact with ATC was subsequently re‑established. The rest of the approach and landing proceeded without incident and the aircraft landed at Bankstown Airport at 1534.

After landing, the pilot conducted an external inspection of the aircraft and found that the VHF antenna on top of the fuselage was missing, and the vertical stabiliser was damaged (Figure 1). Further information on the damage is in Aircraft information and Antenna examination.

Figure 1: Damage to the vertical stabiliser

Source: Jet Aviation

Context

Pilot information

The pilot held a Commercial Pilot (Aeroplane) Licence, issued in December 2019, with a multi‑engine aeroplane instrument rating. At the time of the occurrence, the pilot had approximately 1,980 hours total flying experience, of which 140 hours were accrued on the King Air B200.

Aircraft information

The Beechcraft King Air B200 is a pressurised, low-wing, twin turbine-engine aircraft. It has 2 VHF antennas: COM 1 is fitted on top of the fuselage, and COM 2 is underneath the fuselage (Figure 2). VH-EEL was manufactured in the United States in 2000 and registered in Australia in the same year. CJ Aerospace had been the registered operator of the aircraft since July 2021.

Figure 2: VHF antennas on VH-EEL

Source: CQ Plane Spotting

Aircraft examination

Following the occurrence, the aircraft was sent to a maintenance facility for examination and repair. The examination (not attended by the ATSB) identified that the leading edge of the vertical stabiliser had experienced deformation, and there was damage to the skin and paint on various parts of the empennage (Figure 3 and Figure 4). There also appeared to be some transfer of black material, possibly paint or rubber, onto the right side of the vertical stabiliser. The base of the antenna was still secured to the fuselage by 6 fasteners, but the glass fibre skin of the antenna had failed around each of the fasteners and separated from the aircraft (Figure 5).

Figure 3: Damage on the front of the empennage

Source: Jet Aviation, annotated by the ATSB

Figure 4: Damage on the right side of the empennage

Source: Jet Aviation, annotated by the ATSB

Figure 5: The antenna base still secured to VH-EEL

Source: Jet Aviation

Antenna examination

The detached antenna was not located. The antenna base was examined at the ATSB’s engineering facility in Canberra. The manufacturer’s label indicated that it was manufactured by the Trivec-Avant corporation. The part number was 18-40-01 and the serial number was 11514. The antenna was not original to the aircraft, and its installation date could not be determined. The Trivec-Avant corporation ceased operation in about 2011, and no technical drawings or other details could be obtained for the antenna. However, images of an antenna with the same part number were sourced online (Figure 6). It comprised a base and upper structure with an internal electrical antenna.

Figure 6: Exemplar VHF COM antenna

Source: majorjunque (eBay)

The antenna base from VH-EEL was an aluminium plate with 6 holes for fasteners and a central coaxial connection for the internal electrical antenna (Figure 7). A yellow foam adhered to the top face of the antenna was likely an expanding polyurethane product that was injected into the antenna during its construction in order to increase rigidity (Figure 8). Some fractured glass fibre composite material was observed around each of the fasteners. Fragments of a polymer seal were observed around the edges of the antenna base.

Figure 7: Antenna base from the aircraft

Source: ATSB

Both surfaces of the plate showed discoloration in several locations, identified as deposits on the surface of the metal (Figure 8). The deposits varied in colour. Samples of the dark-coloured and light-coloured deposits were scraped from the antenna using a plastic spatula and analysed for elemental composition using energy-dispersive X-ray spectroscopy (EDS). EDS analysis found that the composition of the light and dark deposits was very similar. Both predominantly contained aluminium, oxygen, and a smaller quantity of chlorine. The presence of chlorine indicated that the plate was exposed to salt water, resulting in corrosion of the aluminium plate, forming aluminium oxide.

Figure 8: Aft end of the antenna base, top face

Source: ATSB

The discolouration was not uniformly distributed over the base, and there were some regions, such as the one shown in Figure 8, where there was no evidence of deposits or discolouration. Similarly, while much of the base’s edge was discoloured, there were some regions underneath the polymer seal that appeared relatively unaffected (Figure 9).

Figure 9: Discolouration under the polymer seal, at the edge of the top face

Source: ATSB

Aircraft maintenance

The aircraft was maintained under a 4-phase inspection program over 800 flight hours or 24 calendar months. Each phase of routine maintenance was conducted sequentially every 200 hours. Inspection of the VHF antennas was conducted in Phase 3. The inspection required personnel to: 

…inspect all external antennas for leading edge erosion and condition of base seals. 

This was last performed on 18 October 2024 with no relevant findings recorded.

The aircraft manufacturer provided guidelines for corrosion control inspections, which were optional and to be used depending on the operating environment. Regarding antennas, the inspection stated the following:

ANTENNAS - Inspect antenna bases for proper sealing. Inspect antenna leading edges for severe erosion. 

These inspections were also last carried out on 18 October 2024 with no relevant findings recorded. 

Neither inspection specified whether antenna removal was necessary.

Similar occurrences

The aircraft manufacturer could not identify any previous instances of antenna separation in flight, but noted that ‘while it is rare, it is not unknown for antennas to crack at the fastener holes’. 

Safety analysis

Based on the aluminium oxide and chlorine found on the surface of the VHF antenna base – a part of the antenna that should be fully enclosed and sealed – the antenna failed in flight due to pre-existing damage resulting from corrosion. The corrosion was almost certainly due to moisture ingress into the unit.

Since most of the antenna was not recovered, there was no way to determine the pathway through which moisture entered the antenna. Most of the seal surrounding the base had separated with the top half of the antenna. There was evidence of moisture under the seal in some regions, while some parts of the seal appeared to have prevented corrosion. The moisture under the seal could indicate a point of ingress, but it is possible that all the corrosion observed under the seals was due to moisture already inside the antenna, rather than evidence that the seal had been compromised.

Beyond the fact that the antenna cracked around the 6 fastener holes, the exact failure mechanism could not be determined. It is possible that corrosion weakened the bond between the polyurethane core and the base or skin of the antenna. This would have reduced the stiffness of the unit, allowing cracks to develop as it flexed during service. Alternatively, moisture could have been absorbed by the glass fibre composite skin, reducing its strength and increasing susceptibility to cracking.

Without an understanding of the mechanisms that led to moisture entering the antenna and the subsequent in-flight separation, it is not possible to determine whether any damage would have been externally visible during the relevant inspection 8 months before the occurrence. Cracking around the fastener holes might not have commenced at that point. Alternatively, damage could have been too small to detect or obscured by the paint.

One alternative possibility to pre-existing damage could not be entirely ruled out: a birdstrike or collision with a remotely piloted aircraft (RPA) could have resulted in antenna separation. However, very few birdstrikes occur above 10,000 ft, and most RPAs are not certified to fly that high. No in-flight RPA loss was reported. There was also no visual evidence of a birdstrike, and any contact with bird or RPA would likely have resulted in a loud bang precipitating the occurrence, rather than a whistling sound followed by the sound of an impact.

Findings

From the evidence available, the following findings are made with respect to the antenna failure involving Beechcraft King Air B200, VH-EEL, 55 km west of Bankstown Airport, New South Wales, on 18 June 2025. 

Contributing factors

• During flight, pre-existing damage due to moisture ingress resulted in the VHF COM 1 antenna failing and separating from the aircraft.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the pilot
• CJ Aerospace
• Textron Aviation (Beechcraft)
• the aircraft maintenance organisation
• the maintenance organisation that examined the aircraft following the occurrence
• Civil Aviation Safety Authority
• Flightradar24.

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the pilot
• CJ Aerospace
• the aircraft maintenance organisation
• Civil Aviation Safety Authority
• Textron Aviation (Beechcraft)
• National Transportation Safety Board (United States).

There were no submissions received.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. About ATSB reports ATSB investigation reports are organised with regard to international standards or instruments, as applicable, and with ATSB procedures and guidelines. Reports must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2025  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 Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the 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.

Investigation summary

What happened

On the afternoon of 13 June 2025, a Pilatus PC‑12, registered VH‑NWI and operated by Armada Aviation, was being used to conduct a charter air transport flight from Essendon Airport, Victoria, to Launceston Airport, Tasmania. On board were a pilot and 4 passengers.

During the approach to Launceston, the aircraft deviated left from the final approach course and intercepted the extended centreline of the adjacent taxiway. The aircraft then continued towards the taxiway where a Cessna 152 (C152) was holding for departure. Approaching the taxiway, the pilot conducted a low-level right then left turn to realign with the runway, before commencing a missed approach. During the manoeuvre the aircraft passed in close proximity to the C152. Following the missed approach, the aircraft conducted a visual circuit and landed without further incident.

What the ATSB found

The ATSB found that the final approach was conducted in clear conditions almost directly into the sun, exposing the pilot to glare. Subsequently, the pilot misidentified the taxiway as the runway and aligned the aircraft with the taxiway's extended centreline. The pilot then corrected the aircraft's flight path at a low level rather than conducting an immediate missed approach. During the manoeuvre the aircraft passed in close proximity to an aircraft on the taxiway.

It was also found that after identifying that the approaching aircraft was aligned with the taxiway, the instructor on board the aircraft on the taxiway made a radio broadcast, likely alerting both the pilot and air traffic control to the situation.

What has been done as a result

Armada Aviation circulated a notice to its aircrew advising them of hazards associated with a visual approach, such as sun glare. Additionally, it made the following changes to its operating procedures:

• Updated the final decision to proceed to landing to include a requirement that the runway was confirmed and clear by 400 ft above ground level, or the approach minima.
• Added a top of descent safety briefing to ensure pilots brief other risks associated with the visual approach segment following an instrument approach, including lighting configuration and sun position.
• Updated the checklist of the final phase of flight to include checking that the runway was confirmed and clear.

Safety message

Sun glare can reduce a pilot’s visual effectiveness even when meteorological visibility is good. When flying visually in such conditions, pilots should crosscheck against available flight and navigation instruments in conjunction with external indicators, such as airport lighting, to verify that the aircraft is on the intended flight path.

If a discrepancy is identified below an appropriate stabilised approach height, an immediate missed approach should be conducted. Low-level manoeuvring outside of the published approach and associated obstacle clearance increases the risk of collision with terrain or objects on the ground.

The investigation

The occurrence

On 13 June 2025, a Pilatus PC-12, registered VH‑NWI and operated by Armada Aviation, was being used to conduct a charter air transport flight from Essendon Airport, Victoria, to Launceston Airport, Tasmania (Figure 1). On board were a pilot and 4 passengers.

Figure 1: Occurrence flight

Source: Google Earth annotated by the ATSB

At 1511 local time, the aircraft commenced the instrument approach procedure for runway 32L[1] at Launceston. The weather at the time was predominately clear skies with few[2] clouds at 3,000 ft, variable wind up to 5 kt and visibility greater than 10 km.

At approximately the same time, the occupants (instructor and student) of a Cessna 152 (C152) on the ground at Launceston contacted air traffic control (ATC) to request taxi clearance for departure on a training flight. Due to the closure of a section of the taxiway (see Figure 4 and the section titled Construction works), the C152 was required to backtrack the runway and vacate onto taxiway A at the runway 32L threshold. The aircraft then turned 180° on the taxiway and stopped with the nose of the aircraft at holding point A. At 1515, the C152 reported to ATC that they had completed the taxi and were clear of the runway.

By this time VH‑NWI was established on the final segment of the approach, approximately 7 NM (13 km) from the runway. Shortly thereafter, ATC cleared the aircraft to land, later reporting that at this time they observed the aircraft established on the final approach. The pilot reported that throughout the final approach, they were looking into the sun and consequently they ‘couldn’t really see much at all’. 

ATC reported again sighting the aircraft when it was approximately 4 NM (7 km) from the runway. At this point the aircraft was approximately 1,340 ft above ground level (AGL) and still aligned with the final approach course (Figure 2).

Figure 2: Final approach flight path

Recorded altitude resolution ± 12.5 ft, over underlying terrain elevation, rounded to nearest 5 ft. Source: ADS-B flight data overlaid on Google Earth, annotated by the ATSB

The pilot advised that, during the approach, they used the autopilot to manage the aircraft’s flight path until approximately 1,000 ft AGL. At this point they disconnected the autopilot and transitioned to looking outside. The pilot recalled that they were still looking into the sun and only seeing one feature on the ground that stood out. Identifying it as the runway, they began visually flying the aircraft towards it. Recorded flight data showed that at approximately 750 ft AGL, the aircraft began to deviate left until it intercepted the extended centreline of taxiway A. From this position the aircraft continued to descend towards the taxiway. At 1519, when the aircraft was approximately 120 ft AGL, weather cameras at the airport recorded images showing both the aircraft on final and the C152 at the holding point (Figure 3).

Figure 3: Weather camera images at 1519

Combination of 2 images: Left image camera bearing 135° (SE) at 1519:04, right image camera bearing 225° (SW) at 1519:02. Source: Bureau of Meteorology, annotated by the ATSB

The instructor on board the C152 recalled that upon looking for the approaching aircraft, they saw that it was lined up with the taxiway. At 1519:12, they made a radio broadcast on the Launceston Tower frequency advising ‘He’s landing on the taxiway’. Following the call, VH-NWI passed above and behind them. It then reappeared on their left side, after conducting a right, then left, turn to align with the runway.

A review of flight data showed that VH-NWI continued to descend as it tracked the taxiway extended centreline until 1519:16, at which point it commenced a right turn (Figure 4). During the turn, the aircraft passed over the taxiway at a height of approximately 45 ft AGL, 15 m behind holding point A, at which the C152 was positioned. Subsequently, the aircraft descended further as it flew over the grassed area between the taxiway and the runway before turning left to align with the runway centreline. During the realignment manoeuvre, the aircraft descended to approximately 15 ft AGL. 

Figure 4: Low-level manoeuvre and missed approach

Recorded altitude resolution ± 12.5 ft, over underlying terrain elevation, rounded to nearest 5 ft. Source: ADS-B flight data overlaid on Google Earth, annotated by the ATSB

The pilot recalled that when not far from the runway environment they became aware that they were approaching the taxiway and in response turned the aircraft towards the runway. They further reported that they were not aware of the C152 at the holding point. While they recalled hearing a radio broadcast as they were moving towards the runway, they did not know who had made it. 

ATC reported that upon hearing the broadcast from the C152 they observed VH-NWI on short final lined up with taxiway A, after which it immediately made a right turn to align with the runway. At 1519:22 they instructed the pilot to go around.[3] The pilot later reported that they heard the instruction from ATC, by which time they had decided to initiate a missed approach. Flight data recorded that the aircraft commencing a climb away from the runway at 1519:31. Following the missed approach, the pilot conducted a visual circuit and the aircraft landed without further incident. Subsequently, the C152 departed.

Context

Pilot

The pilot held an air transport pilot licence (aeroplane) issued in 2013 and a class 1 aviation medical certificate. They had accumulated 4,251 flight hours, of which 659 hours were operating the Pilatus PC‑12. In the previous 90 days, the pilot had accumulated 26 hours, all in the PC‑12. They completed an instrument proficiency check in January 2025.

The pilot reported that they had flown into Launceston Airport a number of times previously, both during the day and at night. They did not recall any prior occasion where sun glare had been an issue during final approach.

Aircraft

VH-NWI was a Pilatus PC‑12, powered by a Pratt & Whitney PT6A‑67B turbine engine driving a 4‑bladed, variable pitch Hartzell propeller. The aircraft was manufactured in 1995 and first registered in Australia in 2002. It was subsequently registered with the operator in 2014.

At the time of the incident, the aircraft had accumulated 8,674 hours total time in service. The aircraft was being maintained in accordance with the operator’s system of maintenance and the PC‑12 maintenance manual. The last periodic inspection was conducted in April 2025, and the maintenance release showed no outstanding items.

Launceston Airport

Runway environment

Launceston Airport had a single grooved asphalt runway 14R/32L (Figure 5). The runway was 45 m wide and approximately 2 km long with a runway heading of 313°. The airport had previously operated a parallel grass runway 14L/32R which had been decommissioned however, the remaining runway had not been renamed to remove the left / right designation. The En Route Supplement Australia (ERSA) provided information on Launceston Airport and identified the single operational runway and the decommissioned runway.

Access to the ends of the runway was via taxiway A located on the western side. The taxiway was 23 m wide and ran the length of the runway. The taxiway surface was a lighter colour compared to that of the asphalt runway.

Figure 5: Launceston Airport runway environment and lighting

Source: Google Earth, annotated by the ATSB

Aerodrome and approach lighting

Launceston Airport was equipped with runway edge lighting, approach lighting, taxiway lighting and precision approach path indicator (PAPI)[4] systems. Approach lighting was installed leading to runway 32L with a PAPI on both sides of the runway. Runway 14R had no approach lighting, and a single PAPI on the left of the runway. When activated, the intensity level of each lighting component could be set between 1‍–‍6, with 1 being the lowest intensity, and 6 being the highest. During tower hours, this setting was controlled by ATC via a panel in the control tower. Outside tower hours the settings were preset.

On the day of the occurrence, all aerodrome lighting was initially inactive. At 1331 local time, the PAPIs for both runway 14R and 32L were activated at an intensity setting of 5. At 1506, 13 minutes prior to the occurrence, the runway edge lighting, taxiway lighting and the approach lighting for runway 32L were activated with an intensity setting of 4. At the same time, the intensity of the PAPIs was reduced to 4. Airservices advised that this intensity setting was selected due to decreasing ambient light associated with winter conditions at that time of day.

The pilot could not recall whether the airport lighting was on during the first approach. During the second approach and landing, they recalled that the lighting was on and thought that it looked dim and was difficult to see.

Construction works

At the time of the incident construction works were being conducted in the area adjacent to the southern apron. These works required the closure of taxiway A between taxiway B and taxiway E (Figure 6). Barriers, unserviceability markers and lighting was deployed at the ends of the closed section of taxiway to prevent access. The presence of works and the taxiway closure were advised both via NOTAM[5] and the airport’s automatic terminal information service (ATIS).[6] The pilot reported being aware that the taxiway was closed.

Figure 6: Airport construction works

Source: Google Earth, inset supplied, annotated by the ATSB

Sun effect during the approach

Sun position

At 1517, the time that the aircraft began to deviate from the final approach course, the sun was positioned 10° to the left of the runway heading and 12° above the horizon. 

Glare

Glare occurs when unwanted light enters the eye. Direct glare comes directly from a light source whereas veiling glare occurs when light is reflected from crazing[7] or dirt on the windscreen. The ATSB research report Limitations of the See-and-Avoid principle examined the effect of glare on pilots stating:

It has been claimed that glare which is half as intense as the general illumination can produce a 42 per cent reduction in visual effectiveness when it is 40 degrees from the line of sight.

When the glare source is 5 degrees from the line of sight, visual effectiveness is reduced by 84 per cent (Hawkins 1987). In general, older pilots will be more sensitive to glare.

Direct glare from the sun and veiling glare reflected from windscreens can effectively mask some areas of the view.

The pilot reported that the aircraft was equipped with a tinted sun visor. They had placed this between their eyes and the sun during the approach however this did not sufficiently reduce the direct glare. Consequently, they reported that for most of the final approach, when not required for power adjustments, they held their right hand in front of their face to block the sun.

They further reported that the windscreen was not crazed or dirty and that the aircraft had been recently washed. They were wearing reading correction glasses which did not provide glare protection and were not wearing any headwear that could be used to shield the sun. 

Stabilised approach criteria

The operator’s procedures defined criteria for stabilised approaches. If an approach was not stable below 300 ft above aerodrome elevation, an immediate missed approach was required to be conducted. These criteria included that:

From 500 ft AGL on the descent, the aircraft shall be:

 - on the correct flight path with only small changes in heading and pitch required to maintain the correct flight path

 - the indicated airspeed is not more than Vref [landing reference speed] (-0/+ 10 kts)

 - the aircraft is in an acceptable landing configuration

 - sink rate is no greater than 600 fpm [feet per minute]; if an approach requires a sink rate greater than 1000 fpm, a special briefing should be conducted

 - power setting is appropriate for the aircraft configuration and is not below the minimum power for approach as defined by the aircraft operating manual

 - all briefings and checklists have been completed.

Safety analysis

The pilot conducted the final approach segment in clear conditions with the sun low in the sky and 10° to the left of runway heading. This exposed them to direct sun glare during the approach. To reduce the effect of the glare they used the aircraft’s visor and their right hand to block the sun. However, some glare remained, and their raised hand likely impacted their view of the runway and associated lighting. Consequently, the pilot misidentified the taxiway as the runway and aligned the aircraft with the taxiway centreline.

During the subsequent segment of the approach, the aircraft’s navigation instruments were likely indicating that the aircraft was to the left of the intended flight path. However, the pilot was looking outside during this time and therefore did not detect the deviation. Furthermore, they did not observe the C152 positioned on the taxiway, likely due to the continued reduced visibility throughout the approach.

The instructor on board the C152 broadcast over the radio after identifying that the approaching aircraft was aligned with the taxiway. Shortly after this broadcast, the aircraft commenced a turn towards the runway. While continuation to landing on the taxiway would likely have resulted in the aircraft passing over the C152, it would probably have resulted in a collision with obstacles associated with the airport’s construction works. As the aircraft commenced its turn toward the runway after the broadcast was made, it is likely that the broadcast contributed to the pilot’s recognition of the situation. However, they advised that they remained unaware that there was an aircraft on the taxiway.  

During the manoeuvre, the aircraft passed behind and in close proximity to the C152. Conducting such a manoeuvre carried a risk of collision with both the C152 and other objects on the ground. Moreover, this manoeuvre was not in accordance with the operator’s stabilised approach criteria where only small heading changes were permitted below 500 ft above ground level (AGL). Upon recognising that the aircraft was not on the intended flight path, an immediate missed approach was required to be conducted. The broadcast from the C152 instructor also alerted air traffic control (ATC) to the situation, prompting them to instruct the pilot to discontinue the landing.

Consideration was given to whether the designation of the landing runway at Launceston Airport as the left runway may have led the pilot to misidentify the taxiway as the left of 2 parallel runways. However, this was not reported by the pilot. Furthermore, they had prior experience operating at the airport and were therefore familiar with the runway layout.

Findings

From the evidence available, the following findings are made with respect to the passing in close proximity to an aircraft on a taxiway during approach involving a Pilatus PC‑12, VH‑NWI, Launceston Airport, Tasmania, on 13 June 2025. 

Contributing factors

• The final approach was conducted in clear conditions almost directly into the sun, exposing the pilot to glare. Subsequently, the pilot misidentified the taxiway as the runway and aligned the aircraft with the taxiway's extended centreline.
• The pilot corrected the aircraft's flight path at a low level rather than immediately conducting a missed approach. During the manoeuvre, the aircraft passed in close proximity to an aircraft on the taxiway.

Other findings

• After identifying that the approaching aircraft was aligned with the taxiway, the instructor on board the aircraft on the taxiway made a radio broadcast, likely alerting both the pilot and air traffic control to the situation.

Safety actions

Safety action by Armada Aviation

Armada Aviation circulated a notice to its aircrew advising them of hazards associated with a visual approach, such as sun glare. Additionally, it made the following changes to its operating procedures:

• Updated the final decision to proceed to landing to include a requirement that the runway was confirmed and clear by 400 ft above ground level, or the approach minima.
• Added a top of descent safety briefing to ensure pilots brief other risks associated with the visual approach segment following an instrument approach, including lighting configuration and sun position.
• Updated the checklist of the final phase of flight to include checking that the runway was confirmed and clear.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the pilot and operator
• the pilot and operator of the aircraft on the taxiway
• Bureau of Meteorology
• Launceston Airport
• Airservices Australia
• recorded data from the electronic flight bag (EFB) on the aircraft. 

References

Australian Transport Safety Bureau (ATSB) (2004). Limitations of the see-and-avoid principle, /sites/default/files/media/4050593/see_and_avoid_report_print.pdf, ATSB, accessed 13 June 2025

Hawkins, F.H. (1987). Human Factors in Flight, Gower, Aldershot.

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the pilot and operator
• the pilot and operator of the aircraft on the taxiway
• Launceston Airport
• Airservices Australia
• Civil Aviation safety Authority.

Submissions were received from:

• the operator.

The submission was reviewed and, where considered appropriate, the text of the report was amended accordingly.

Purpose of safety investigations The objective of a safety investigation is to enhance transport safety. This is done through:  identifying safety issues and facilitating safety action to address those issues providing information about occurrences and their associated safety factors to facilitate learning within the transport industry. It is not a function of the ATSB to apportion blame or provide a means for determining liability. At the same time, an investigation report must include factual material of sufficient weight to support the analysis and findings. At all times the ATSB endeavours to balance the use of material that could imply adverse comment with the need to properly explain what happened, and why, in a fair and unbiased manner. The ATSB does not investigate for the purpose of taking administrative, regulatory or criminal action. Terminology An explanation of terminology used in ATSB investigation reports is available here. This includes terms such as occurrence, contributing factor, other factor that increased risk, and safety issue. Publishing information Released in accordance with section 25 of the Transport Safety Investigation Act 2003 Published by: Australian Transport Safety Bureau © Commonwealth of Australia 2025   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 Commonwealth Coat of Arms, ATSB logo, and photos and graphics in which a third party holds copyright, this report is licensed under a Creative Commons Attribution 4.0 International licence. The CC BY 4.0 licence enables you to distribute, remix, adapt, and build upon our material in any medium or format, so long as attribution is given to the 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.

Investigation summary

What happened

On 29 April 2025, the flight crew of an Alliance Airlines Fokker 100 aircraft, VH-FKF, were conducting scheduled passenger flight QQ 3811, from West Musgrave Airport to Perth Airport, Western Australia. The captain was the pilot flying and the first officer was the pilot monitoring.

The flight crew received an air traffic control clearance to conduct a visual approach following a standard instrument arrival to Perth Airport’s runway 03. The approach required a 90° turn onto final that resulted in the aircraft being aligned with the runway and on the correct approach profile about 4 NM from the runway threshold. 

Passing about 1,000 ft radio altitude, the aircraft was above the operator’s permitted airspeed‑related stabilised approach criteria. However, a go‑around was not initiated and the aircraft landed uneventfully at 1539 local time.

What the ATSB found

The ATSB found that the pilot flying incorrectly assessed that the applicable stabilisation height was 500 ft. As a result, they did not manage the aircraft's energy state to ensure the stabilised approach speed requirement was met by 1,000 ft.

The pilot monitoring did not announce that the approach was unstable when the airspeed requirement was not met at 1,000 ft. This may have been influenced by their workload, the required check being completed slightly late, and an assessment that the airspeed was reducing.

Finally, although not contributory to the occurrence, during descent the captain inadvertently omitted to change the altimeter setting from standard pressure to QNH. This resulted in the left altimeter indicating 300 ft lower than the right altimeter. Neither flight crewmember detected the incorrect setting during 2 subsequent checks prior to landing.

Safety message

This incident highlights the importance of flight crew having a common understanding of the approach requirements. The International Air Transport Association provided guidance for flight crew to avoid an unstable approach. This included to:

• be aware of the stable approach criteria
• comply with the stable approach criteria published in the standard operating procedures (SOP)
• advise air traffic control when unable to comply with a clearance that would result in the aircraft being too high and/or too fast
• prepare for visual approaches by briefing speed/altitude/configuration gates, equivalent to those of an instrument approach, and follow the published visual approach pattern in the manufacturer’s or operator’s SOP
• configure the aircraft for landing at some predetermined distance from the airport or altitude, after which only small corrections to pitch heading and power setting should be made.

This incident also illustrates the need for effective flight crew monitoring. The Flight Safety Foundation identified that monitoring can be improved by standard operating procedures, increased emphasis and practice, and stated:

One of the most important aspects of a safe flight operation is the requirement for crewmembers to carefully monitor the aircraft’s flight path and systems, as well as actively cross-check each other’s actions.

The investigation

The occurrence

On 29 April 2025, the flight crew of an Alliance Airlines (Alliance) Fokker 100 aircraft, VH‑FKF, were conducting scheduled passenger flight, callsign ‘Unity’ (QQ) 3811, from West Musgrave Airport to Perth Airport, Western Australia. The captain was the pilot flying (PF), and the first officer was the pilot monitoring (PM).[1] 

At about 1449 local time, while in the cruise at flight level (FL) 340,[2] the flight crew received an air traffic control (ATC) clearance to conduct the KABLI One Victor standard instrument arrival (STAR) to Perth Airport’s runway 03 (Figure 1). 

Before commencing descent, the flight crew reviewed the Perth Airport automatic terminal information service (ATIS), which included QNH[3] of 1,024 hPa and wind from 080° at 10 kt. The flight crew calculated the landing reference speed (V_REF) for the aircraft’s weight using landing flap 25 to be 122 kt and the approach speed (V_APP) as 132 kt. 

Note: Airservices advised that the VOR depicted on the chart is historical, does not serve a navigational purpose for the depicted procedure and can be removed. Source: Jeppesen, annotated by the ATSB

At about 1512, the flight crew were cleared to descend to FL 190 ‘when ready’ and instructed to switch to another Melbourne Centre ATC frequency. The PM reported having commenced descent from FL 340 at 1517, and 3 minutes later, the controller instructed them to maintain 250 kt (airspeed) from KABLI until advised and cleared them to descend via the STAR to 9,000 ft. 

The aircraft passed waypoint KABLI at about 1527, descending through about FL 166 and then turned to track 50 NM via the STAR to fly-by waypoint[4] OBGOS, 5 NM from the runway 03 threshold. 

During descent, approaching the transition level (FL 110),[5] the required transition check involved:

• each flight crewmember setting the current local QNH (in this instance 1,024 hPa), on the altimeter set panel
• changing the subscale for the captain’s (no 1) and first officer’s (no 2) primary flight displays (PFD), from standard (STD) to QNH by pressing the QNH/STD button on the electronic flight instrument system panel (Figure 2).

When set to QNH, the PFD displays the value selected on the altimeter set panel in hPa. When set to STD, the PFD displays ‘STD’.  

Figure 2: Altimeter set panel and electronic flight instrument system (EFIS) panel (not collocated) 

Source: Fokker, annotated by the ATSB

Recorded flight data showed that the first officer’s PFD altimeter reference pressure changed from STD to QNH passing about FL 114, but the captain’s PFD remained on STD. The standby altimeter pressure setting was not recorded, but the captain reported having set the standby altimeter to QNH.

After each setting their own PFD, the standard operating procedures required each flight crewmember to crosscheck all 3 altimeters were set correctly. The PF was required to call out ‘Transition [1,024] set. Passing [x] ft now. Speed [x] knots’. The PM was to respond, ‘[x] ft checked’. The crew reported completing the checks, but did not identify that the no 1 PFD was incorrectly set to STD and therefore indicating about 300 ft lower than the no 2 PFD (and the standby altimeter).

At about 1527, the PM contacted the Perth Approach controller, and at 1528:44, passing FL 136, was instructed to increase speed to 270 kt then cancel further speed restrictions, and descend to 7,000 ft (see the section titled Air traffic control speed instructions). About 4 minutes later, they were cleared to descend to 3,000 ft and report when visual.[6] The PM read back ‘descend 3,000’ and advised they were visual. The controller then cleared the flight crew to conduct a visual approach, which the PM read back. 

At 1533, ATC broadcast that a new ATIS was current and the QNH had changed to 1,023 hPa. At that time, the aircraft was descending through about 5,000 ft. Passing 5,000 ft, the standard procedures required the PM to call out ‘5,000 ft on QNH [1,023]’ and the PF’s required response was ‘QNH [1,023] checked’. Both flight crewmembers recalled having set and then confirmed all 3 QNH displays were set to 1,023. However, they did not identify the altitude discrepancy between altimeters, or the no 1 PFD subscale setting of STD. 

As ATC had cancelled the STAR speed restrictions, the flight crew did not have to adhere to the airspeeds on the approach chart. Therefore, as the aircraft descended through 5,000 ft, it passed waypoint VAVGA at an indicated airspeed of about 270 kt – 40 kt faster than the published speed restriction. The aircraft subsequently passed waypoint KARGO, descending through about 3,300 ft at 230 kt airspeed – 45 kt faster than the published speed restriction. 

Approaching 2,500 ft and at about 200 kt airspeed, the PM selected flap 8. As the aircraft descended through 2,500 ft, the flight crew were required to crosscheck the radio altitude[7] indicating on both PFDs. The flight crew confirmed the radio altitudes matched, but again did not identify the no 1 altimeter subscale incorrectly set to STD. At the same time, the approach controller instructed the PM to change to the Perth Tower ATC frequency. The PM contacted the aerodrome controller at 1536:15. 

A review of recorded flight data identified that, at 1536:46, the aircraft commenced the right turn past waypoint OBGOS (Figure 3), at about 2,000 ft above mean sea level (AMSL) and 180 kt airspeed. During the turn, landing gear was extended, followed by flap 25. Just before the aircraft was levelled, the captain deployed the speed brake.

Figure 3: Recorded flight data showing VH‑FKF turn past fly‑by waypoint OBGOS

Source: Recorded flight data overlaid on Google Earth, annotated by the ATSB

The captain reported identifying a discrepancy between the altimeter and the radio altitude during the turn, passing about 1,500 ft, and assessed it as an instrument error. As they were visual, the captain was primarily focused outside, ensuring the aircraft aligned with the runway and on the correct profile by following the precision approach path indicator (PAPI) guidance. 

About 1 minute after commencing the turn, the aircraft was aligned with the runway centreline, about 4 NM from the threshold, at 1,250 ft radio altitude and 172 kt airspeed. The captain later reported that the airspeed was faster than normal due to their focused attention on the observed altimeter discrepancy. As the aircraft descended through about 1,000 ft radio altitude (also about 1,000 ft above aerodrome elevation), the PM assessed that all stabilised approach criteria were met and called ‘stable’, and the flight crew continued the approach. 

The aerodrome controller cleared the flight crew to land as the aircraft passed about 600 ft radio altitude. At 1539, the aircraft landed normally within the touchdown zone. After landing, the captain realised that the no 1 PFD was set to STD and changed the setting to QNH.

Context

Flight crew information

The captain held an air transport pilot licence (aeroplane), class 1 aviation medical certificate, and had accrued 24,797 hours total flying time, 1,497 of which were in the Fokker 70 and 100 aircraft types. 

The first officer held a commercial pilot licence (aeroplane), class 1 aviation medical certificate, and had 4,600 hours total flying time, 520 of which were on the Fokker aircraft types. 

The captain reported their fatigue as 3/7 and the FO as 1/7.[8] There was no evidence fatigue was a factor in this occurrence. 

Key speeds

The flight crew used the onboard performance tool to calculate the landing reference speed (V_REF) of 122 kt. The Alliance Airlines Fokker 70–100 Aircraft Operating Manual (AOM) Supplement (SUP) defined the approach speed as V_REF + 5 kt with the following wind correction:

The approach speed (VREF + 5) should be corrected for wind, including gusts, as follows:

Wind 0 up to 10 knots inclusive:                     no correction

Wind (+gust) more than 10 up to 20kts inclusive:     add 5kts

Wind (+gust) more than 20kts:                       add 10 kts

Based on the ATIS specified wind speed of 10 kt and the Alliance AOM SUP, there was no wind correction required and the V_APP was 127 kt. However, the crew added 5 kt for wind correction and used V_APP of 132 kt. The flight crew could not recall their decision‑making around the wind correction, but reported it may have included consideration of the wind the aircraft was experiencing at the time of the calculation, and the aerodrome forecast wind speed of 12 kt. 

The Fokker Aircraft Operating Manual specified maximum flap extended speeds of:

• flap 8° – 250 kt
• flap 15° and 25° – 220 kt
• flap 42° – 180 kt

and the maximum landing gear extended and operating speed was 200 kt. 

Air traffic control speed instructions

Airservices Australia’s Aeronautical Information Publication (AIP) included the following content related to airspeed requirements:

ENR 1.5 – 47:

10.1.5      When a clearance for the termination procedure is authorised e.g. visual approach, the published STAR speed restrictions still apply unless specifically cancelled. 

10.2.5      Cancellation of ‘published speed restrictions’ cancels all speeds published on the STAR chart. Cancellation of ‘ATC-issued speed control instruction’ cancels any speed control instructions issued by ATC. Airspace speed limitation must be complied with unless specifically cancelled. 

ENR 1.4 – 13:

4.1 Airspace speed limitations stated ‘N/A’ for IFR aircraft in Class C (and Class A) airspace. 

GEN 3.4 – 56 included the phraseology [DESCEND VIA STAR TO (level)], CANCEL SPEED RESTRICTION(S), for the circumstances:

During a STAR descent:

    a. comply with published level restrictions
    b. follow the lateral profile of the STAR
    c. published speed restriction and ATC-issued speed control instructions are cancelled

ENR 1.6 – 5:

5.2           The pilot must request an alternative when at ATC-issued speed control instruction is unacceptable on operational grounds. 

5.5           A pilot will be advised when a specific ATC-issued speed control instruction is no longer necessary. Unless otherwise stated, an ATC-issued speed control instruction applies until the aircraft reaches the point in the descent profile where the speed would normally be reduced below that assigned by ATC. Except for a STAR, a DME arrival, or unless otherwise specified, a clearance for final approach or a clearance for a visual approach terminates speed control.

On this flight, after being cleared for the STAR, the flight crew were instructed to ‘increase speed to 270 knots and then cancel further speed restrictions’. About 3 minutes later, they were cleared to conduct a visual approach.  

Airservices Australia advised that in this case, the aircraft was expected to maintain 270 kt until the point of normal profile speed reduction. The flight crew could then resume their desired profile speed. 

The aircraft maintained 270 kt until it passed waypoint VAVGA, less than 2 minutes after being cleared for a visual approach. The captain reported that the cancellation of speed restrictions created a ‘subtle pressure’ to maintain a higher airspeed, and contributed to the faster approach speed.  

Recorded flight data

At 1528:44 the aircraft was 40 NM from OBGOS at 13,915 ft (corrected barometric altitude for comparison) and 250 kt when ATC instructed the flight crew to increase speed to 270 kt then cancel further speed restrictions. 

At 1531:42, the aircraft was 24.6 NM from OBGOS at 7,698 ft barometric altitude and 272 kt when cleared for a visual approach. The aircraft then continued at about 270kt to waypoint VAVGA, 16 NM from OBGOS. From there, about 140 kt deceleration to V_APP (132 kt) was required by 1,000 ft. 

At VAVGA the aircraft was at 5,000 ft, 1,600 ft higher than the minimum permitted altitude. To that point, the average descent rate since the crew were instructed to increase to 270 kt (40 NM from OBGOS), had been 1,938 fpm. A descent rate of 2,286 fpm was required for the aircraft to have passed VAVGA at 3,400 ft and subsequently achieve the required deceleration. 

Figure 4 depicts key parameters of the recorded flight data during the approach from 3,000 ft. At 1,000 ft radio altitude, the recorded airspeed was 158 kt, which reduced to the stabilised criterion of V_APP + 10 (142 kt) by 800 ft, 9 seconds later. The vertical speed was not recorded but was calculated from the change in recorded altitudes.

Table 1 shows the derived vertical speed, with exceedances of the stabilised criterion of 1,000 fpm between about 1,000 ft and 450 ft radio altitude. These included an expected increase in vertical speed associated with the retraction of the speed brake, passing about 800 ft radio altitude. The recorded data also showed that the aircraft was within one dot of the 3° glideslope from 1,000 ft and therefore on the correct approach profile.

Figure 4: Recorded flight data of approach to runway 03 from 3,000 ft

Source: ATSB analysis of recorded flight data

Table 1: Descent rates from about 1,000–400 ft radio altitude

Alliance Airlines documented procedures

Descent rates

The OPPM stated: 

The following values for the rate of descent below the transition altitude shall not normally be exceeded: 

• 3000 fpm down to an altitude of 3000 ft above aerodrome level (AAL). 

• 2000 fpm down to an altitude of 2000 ft AAL transitioning to 1000 ft AAL 

• 1000 fpm below 1000 feet AAL.

Visual approach 

The OPPM stated that in visual meteorological conditions (VMC)[9] on a visual approach, the aircraft must join the circuit on the upwind, crosswind or downwind leg, or make a straight-in approach after establishing on final approach by 5 NM.

The Alliance Airlines F70–100 AOM SUP (versions 2.5 published in March 2024 and 2.6 published 10 June 2025) included section 7.12 Visual approach with subheadings 7.12.1 Procedure and 7.12.2 Straight-in visual approach. Both subsections included: 

If not in the correct landing configuration at 1000ft AAL [above aerodrome level], a go around must be initiated.

If not stabilised on speed and glide path at 500ft AAL, a go around must be initiated.

Additionally, section 7.12.2 Straight-in visual approach included:

The following are the requirements for configuring a straight in approach. 

• The aircraft must be configured landing gear down and flap 25 prior to 1500ft AAL and a 5nm final.

• Select flap 42 (if required) at 1300ft AAL. 

Vertical speed should not exceed 1000ft/min inside 5nm to touchdown.

Stabilised approach criteria

The Alliance Airlines OPPM defined a stabilised approach as one that met the following criteria: 

a) the correct flight path;

b) only small changes in heading/pitch are required to maintain the correct flight path;

c) the aircraft speed is not more than V_APP + 10 knots indicated airspeed and not less than V_REF;

d) the aircraft is in the correct landing configuration;

e) sink rate is no greater than 1,000 feet per minute

f) thrust or power setting is appropriate for the aircraft configuration;

g) all briefings and checklists have been completed;

h) specific types of approaches are stabilized if they also fulfil the following

i. instrument landing system (ILS) approaches must be flown within one dot of the glideslope and localizer

ii. a Category II or Category III ILS approach must be flown within the expanded localizer band

i) unique approach procedures or abnormal conditions requiring a deviation from the above elements of a stabilized approach require a special briefing to have been completed prior to beginning the approach.

• Note 1: A momentary excursion is permitted for points (c) & (e). A momentary excursion is defined as a deviation lasting only a few seconds and where every indication is that it will return to the stabilised criteria as listed in points (c) & (e).

• Note 2: Where the nominal descent path for a particular approach requires a descent rate greater than 1000 fpm. This is only permitted when expected rates of descent have been briefed prior to the approach being commenced. 

Stabilized Heights 

All flights shall meet all of the above stabilized approach criteria by 1,000 feet above aerodrome level except under the following circumstances: 

Visual approach:

• Speed may be higher than V_APP + 10, provided it is within limits and expected to reduce to V_APP+10 or below by no later than 500ft AAL.

• Note 3: Visual conditions as defined by Jeppesen AUS or AIP - the pilot has established and can continue flight to the airport with continuous visual reference to the ground or water; and visibility along the flight path is not less than 5000m.

Visual circuit:

• Manoeuvring shall be completed no later than 500 AAL.

 Circling approach 

• Final Flap shall be selected no later than leaving the Circling Altitude.

• By 500ft AAL for the following shall be achieved.

          ◦ Approach Speed must be achieved

          ◦ Checklists must be completed

          ◦ Manoeuvring must be completed.

…[RNP-AR approach]

An approach that does not meet, or subsequently exhibits sustained deviations outside of these criteria requires an immediate go-around.

On 3 April 2025, Alliance issued Operations notice 25-038:

The Alliance Airlines Fokker AOM SUP (v2.5 released March 2024 and v2.6 released 10 June 2025) included the following visual approach standard calls:

Hierarchy of manuals

The Alliance Airlines hierarchy of manuals stated that the Operations Policy and Procedures Manual (OPPM) was the primary manual, and the aircraft operating manuals and supplements were supporting manuals. The OPPM section 7 – Standard operating procedures stated:

All Pilots must be fully aware and observant of the procedures and calls outlined in this chapter. Operate Alliance Airlines aircraft in accordance with the appropriate Aircraft Operating Manual and the Alliance Airlines Operations Policy and Procedures Manual. If information in either of these manuals conflict, the information in the most recent revision of the Aircraft Operating Manual or Operations Notice ‘date’ can be assumed to be valid.

Based on the hierarchy, the operations notice replaced the stabilised approach criteria documented in the OPPM. At the time of the incident, the operations notice had a more recent publication date than the AOM SUP and therefore took precedence where the information conflicted. However, an amendment to the AOM SUP was published after the incident (and subsequent to the operations notice), which did not amend the information that conflicted with the operations notice. 

Alliance Airlines advised that it intended the flight crew to comply with the operations notice, which at the time of writing was to be incorporated into an amended OPPM. Additionally, a further amendment would be made to the AOM SUP to remove conflicting information.  

Applicable stabilisation height 

Alliance assessed that for the visual STAR via OBGOS the applicable stabilisation height was 1,000 ft, ‘because the STAR has FMS [flight management system] guidance and is not a visual circuit or circling manoeuvre’. However, Alliance’s stabilisation heights depended on whether a visual straight-in approach, instrument approach or visual circling/circuit approach was being conducted. The procedure did not describe the height based on whether an arrival was coded in the FMS. Alliance advised that initially the flight did not flag an exceedance in Alliance’s flight data analysis program and would therefore not have been further reviewed had the flight crew not reported setting the incorrect QNH. Having reviewed the recorded flight data, Alliance initially determined that there were no speed exceedances, and although the descent rate exceeded 1,000 fpm between 1,000 and 500 ft, this was considered transitory in nature and therefore was permitted in accordance with the stabilised approach criteria. However, Alliance subsequently assessed that the duration of the speed exceedance was not momentary.

The captain and first officer were familiar with the content of the operations notice. The first officer identified the approach as a straight‑in visual approach and therefore made the appropriate callout of ‘1,000 ft’, assessed that the stabilised approach criteria were met, then called ‘stable’. The first officer reported that due to the ‘busyness of [turning] the corner’, this check may have occurred slightly below 1,000 ft. Additionally, they reported assessing that the airspeed was reducing as required and subsequent vertical speed exceedances were momentary and therefore acceptable within the criteria.  

Prior to Alliance Airlines issuing operations notice 25‑038, 26 days prior to the occurrence, the stabilisation height for a visual approach in VMC was 500 ft. However, the captain assessed that the visual approach via the STAR and waypoint OBGOS was not specifically defined in the operations notice, either by a visual approach with a 5 NM final, or a visual circuit, which did not permit joining the circuit on a base leg. Further, that for the intent of a stabilised approach, the approach was more aptly comparable to a visual circuit, albeit that the aircraft entered the circuit on base leg before turning onto final. The captain therefore interpreted the applicable stabilisation height to be 500 ft. As pilot flying, the captain reported having flown the approach with the intent to be stable by 500 ft, and had observed that otherwise the airspeed was too high at 1,000 ft. 

The ATSB assessed that the approach was a straight‑in visual approach, though by design had a final leg somewhat less than 5 NM, and therefore based on the operations notice, the applicable stabilisation height was 1,000 ft. 

Safety analysis

The flight crew reported performing the transition checks, which required each flight crewmember setting and then crosschecking that all 3 altimeters were set to the correct pressure subscale. However, neither flight crewmember identified that the captain’s primary flight display (PFD) had not been switched from standard (STD) to barometric pressure (QNH). This was again missed at the required 5,000 ft check, which coincided with air traffic control (ATC) advising of a change in the QNH.

The flight crew also did not identify the error when they later crosschecked that the radio altitudes matched on both PFDs, when passing about 2,500 ft. It could not be determined why this was missed, but it resulted in the captain’s PFD indicating about 300 ft lower than the aircraft’s actual height. 

Having the altimeter set correctly is important to ensure the aircraft is operating at the same height basis as other aircraft in the same airspace, and to ensure adequate separation from terrain. In this case, indicating 300 ft lower than actual did not increase the risk of a collision with terrain. Additionally, had the captain, as pilot flying, based the approach profile on the indicating lower altitude, it should have resulted in the aircraft being stabilised 300 ft higher than the stabilisation height. However, by that stage, the flight crew were referencing radio altitude rather than barometric altitude. 

The captain reported identifying the discrepancy between the altimeter and the radio altitude at about 1,500 ft, during the turn onto final. Their focus on the discrepancy may have contributed to the delay in achieving the required stabilised speed. However, having assessed the required stabilisation height as 500 ft, the captain was unconcerned (although aware) that the airspeed was fast at 1,000 ft. The airspeed reduced below the stabilisation criterion by 800 ft.  

The first officer’s assessment that the 1,000 ft stabilised height applied, and all requirements were met, was consistent with Alliance Airlines’ assessment that the vertical speed deviations were transient and acceptable within the stabilisation criteria. However, at 1,000 ft, the airspeed was 26 kt above the approach speed, with only a 10 kt exceedance permitted. The pilot monitoring did not call ‘unstable’ as required by the stabilised approach policy. This may have been influenced by the pilot monitoring experiencing the turn onto final as a ‘busy corner’, the required checks being completed slightly below 1,000 ft and an assessment that the airspeed was reducing.   

The ATC speed instructions resulted in the aircraft being significantly faster than the published speeds during the standard instrument arrival (STAR). Additionally, the captain reported some pressure to keep the speed up during the approach. However, according to the Airservices Australia Aeronautical Information Publication (AIP), an ATC‑issued speed instruction only applied to the point where the flight crew would reduce the speed on the normal profile for the approach. Furthermore, if flight crew assessed a speed control instruction was unacceptable, they were to request an alternative. 

The aircraft’s average descent rate was less than 2,000 fpm between about 14,000 ft to 5,000 ft, during which 270 kt airspeed was maintained. As Alliance permitted up to 3,000 fpm above 3,000 ft, there was opportunity to descend faster earlier in the approach, which would have facilitated more effective speed reduction later in the approach. The airspeed was below the 200 kt landing gear extension speed for about 1 minute before the landing gear fully extended during the turn onto final. As the airspeed was only above the required stabilised approach speed at 1,000 ft for 9 seconds, extending the landing gear, flap, and/or speed brake slightly earlier, would likely have ensured the stabilised criteria could be met. 

Findings

From the evidence available, the following findings are made with respect to the unstable approach involving Fokker 100, VH-FKF, near Perth Airport, Western Australia on 29 April 2025.

Contributing factors

• The pilot flying incorrectly assessed that the applicable stabilisation height was 500 ft. As a result, they did not manage the aircraft's energy state to ensure the stabilised approach speed requirement was met by 1,000 ft.
• The pilot monitoring did not announce that the approach was unstable when the speed‑related stabilised approach criteria was not met at 1,000 ft. This may have been influenced by workload, the required check being completed slightly late, and an assessment that the airspeed was reducing.

Other factors that increased risk 

• Passing the transition level, the captain inadvertently omitted to change the altimeter setting from standard pressure to QNH, resulting in the left altimeter indicating 300 ft lower than the right altimeter. Neither flight crewmember detected the incorrect setting during 2 subsequent checks prior to landing.

Sources and submissions

Sources of information

The sources of information during the investigation included:

• the flight crew
• Alliance Airlines
• Honeywell
• Airservices Australia
• the Bureau of Meteorology
• recorded flight data from the aircraft. 

Submissions

Under section 26 of the Transport Safety Investigation Act 2003, the ATSB may provide a draft report, on a confidential basis, to any person whom the ATSB considers appropriate. That section allows a person receiving a draft report to make submissions to the ATSB about the draft report. 

A draft of this report was provided to the following directly involved parties:

• the flight crew
• Alliance Airlines
• Airservices Australia
• the Civil Aviation Safety Authority
• Fokker
• the Dutch Safety Board.

Submissions were received from:

• Alliance Airlines
• Airservices Australia
• Fokker
• the Dutch Safety Board.

The submissions were reviewed and, where considered appropriate, the text of the report was amended accordingly.

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