Aviation safety investigations & reports

Collision with terrain involving Cessna A150M, VH-CYO 5 km west-south-west of Peachester, Queensland, on 23 June 2021

Investigation number:
AO-2021-025
Status: Completed
Investigation completed
Phase: Final report: Dissemination Read more information on this investigation phase

Final

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What happened

On 23 June 2021, a Cessna A150M Aerobat, registered VH-CYO, departed from the Sunshine Coast Airport, Queensland, with an instructor and student pilot on board. The purpose of the aerobatic training flight was to introduce and practice spin entry and recovery techniques.

The aircraft climbed to about 6,000 ft above mean sea level and arrived at the area intended to conduct aerobatics about 20 minutes after departure. Radar data showed that the aircraft then entered into a left spin that continued for about 55 seconds until the aircraft impacted terrain. The instructor and student were fatally injured, and the aircraft was destroyed.

What the ATSB found

Forward movement of the aircraft and the low angle of entry indicated that the aircraft was most likely in the process of recovering from the spin when it impacted with trees.

Examination of the aircraft did not identify any mechanical defect. However, the aircraft was significantly disrupted and therefore functionality of the flight controls was unable to be fully assessed. Pre- and post-accident medical information did not identify any underlying conditions in either pilot that may have contributed to the accident.

The aerobatics instructor was experienced in conducting spins, primarily in the Pitts Special aircraft type. However, it was likely that they had no experience in spinning a Cessna A150 Aerobat or any similar variant. The instructor’s theoretical spin training provided to the aerobatic student pilot (and another student at the same time) did not include instruction on the recovery technique as prescribed in the Aerobat pilot’s operating handbook (POH). Further, the ATSB established that it was likely the instructor intended to practice 2 spin recovery techniques. One of those techniques, broadly known as the Mueller/Beggs recovery method, has been shown to not recover a Cessna A150 Aerobat established in a spin to the left. The other method known as PARE, aligned closely with the aircraft’s POH and, if utilised, it would recover the aircraft from a spin.

The ATSB was unable to ascertain which of the recovery technique(s) was being utilised at the various stages of the spin recovery preceding the accident. For this reason, the ATSB was unable conclude if the use of an inappropriate recovery technique contributed to the accident.

What has been done as a result

The ATSB has issued a Safety Advisory Notice SAN (AO-2021-025-SAN-001) for aerobatic pilots and aerobatic instructors who conduct spins utilising the Mueller/Beggs spin recovery method, to raise awareness of its limitations.

Safety message

Although the reason for the accident could not be fully established, the investigation identified that one of the spin recovery methods that was to be practiced on the day of the accident would most likely not recover the Cessna A150M Aerobat from a spin.

This investigation presents a timely reminder that pilots should review the pilot’s operating handbook of the aircraft type that they intend to operate. Prior to intentionally spinning an aircraft, pilots should obtain instruction and/or advice in spins and recovery techniques from an instructor who is fully qualified and current in spinning that model. Further, aerobatic pilots and instructors should be aware and also teach the Meuller/Beggs method of spin recovery advantages, but most importantly its limitations in that it will not recover all aircraft types from a spin.

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The occurrence

Context

Safety analysis

Findings

Safety actions

Glossary

Sources and submissions

ATSB

Safety Advisory Notice

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Safety Advisory Notice

To aerobatic pilots and instructors

All aircraft types do not spin and recover in the same way. Know your aeroplane type, what recovery techniques will work and what recovery techniques will not work.

What happened

On 23 June 2021, while conducting spin entry and recovery training from 5,800 ft above ground level, the Cessna A150M Aerobat did not fully recover from a spin to the left before impacting terrain.

Factors uncovered during the investigation

The aerobatics instructor was experienced in conducting spins, primarily in the Pitts Special aircraft type. However, it was likely that they had no experience in spinning a Cessna A150 Aerobat or any similar variant.

The instructor’s theoretical spin training provided to the aerobatic student pilot (and another student at the same time) did not include instruction on the recovery technique as prescribed in the Aerobat pilot’s operating handbook (POH). Further, the ATSB established that it was likely the instructor intended to practice 2 spin recovery techniques (Mueller/Beggs and PARE). The technique broadly known as the Mueller/Beggs recovery method, has been shown to not recover a Cessna A150 Aerobat established in a spin to the left. However, the PARE method was similar to Aerobat POH method, with less emphasis on the brisk full forward movement of the control yoke.

Safety advisory notice

AO-2021-025-SAN-001: The ATSB strongly encourages all aerobatic pilots and aerobatic flight instructors to be aware:

  • the Mueller/Beggs method of spin recovery does not recover all aircraft types from a spin
  • the Mueller/Beggs spin recovery method limitations should be emphasised during spin theory training
  • the Mueller/Beggs method of spin recovery will not recover a Cessna A150 Aerobat or similar variants from a spin in some circumstances
  • they should review the pilot’s operating handbook of the aircraft type that they intend to operate for the recommended spin recovery technique
  • prior to doing spins in any model aircraft, pilots should obtain instruction and or advice in spins from an instructor who is fully qualified and current in spinning that model.

Read more about this ATSB investigation: Investigation: AO-2021-025 - Collision with terrain involving Cessna A150M, VH-CYO 5 km west-south-west of Peachester, Queensland, on 23 June 2021 (atsb.gov.au)

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Preliminary

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This preliminary report details factual information established in the investigation’s early evidence collection phase, and has been prepared to provide timely information to the industry and public. Preliminary reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003.

The occurrence

Two private pilots contracted an aerobatics instructor to provide aerobatic flight training. On the morning of 23 June 2021, the three pilots gathered at the Sunshine Coast Airport, Queensland, for a pre-flight briefing. The briefing contained theoretical information about spin[1] training and recovery techniques, which were intended for the practical component of the aerobatic flights that day. The pilots had hired a Cessna A150M Aerobat, registered VH-CYO, from the Sunshine Coast Aero Club for the practical flight training.

At 1103 Eastern Standard Time,[2] VH-CYO took off from the Sunshine Coast Airport, with the instructor and one of the student aerobatic pilots on board. The flight was being conducted under visual flight rules (VFR), and visual meteorological conditions existed during the flight.

The aircraft departed to the south-west and climbed to about 6,000 ft above mean sea level (AMSL) (Figure 1). It arrived at the area intended to conduct aerobatics about 20 minutes after departure.

Figure 1: VH-CYO flight track radar data showing take-off point and accident site

VH-CYO flight track radar data showing take-off point and accident site

Source: Google Earth, annotated by the ATSB

Figure 2 shows recorded radar data for the last 3 minutes of the flight. It indicates that, within the last 90 seconds, the aircraft turned left, decelerated while maintaining altitude, and then descended rapidly. Shortly after, at about 1122, the aircraft impacted terrain. The aircraft was destroyed and the two occupants were fatally injured.

Figure 2: VH-CYO last 3 minutes of recorded flight data viewed from the left and above

VH-CYO last 3 minutes of recorded flight data viewed from the left and above

Radar positions (depicted by green pins) were recorded every 5 seconds. The last two points depicted without pins were predictive in nature and were not considered to be accurate. Source: Google Earth, annotated by the ATSB

The aircraft was reported missing by a member of the aero club at about 1515 EST. A subsequent search found the wreckage in bushland near Peachester several hours later.

Context

Aircraft information

The Cessna 150 is a high wing, two-seat, single piston engine aeroplane designed for flight training. The Cessna A150M Aerobat model was designed to conduct aerobatic training.

VH-CYO was manufactured in 1976 and first registered in Australia in 1995. It had been owned by the Sunshine Coast Aero Club since March 2021.  

Recorded information

The aircraft flight path was derived from primary[3] and secondary[4] surveillance radar data recorded by Airservices Australia. The data included the aircraft’s position with a time stamp and altitude at 5-second intervals. A groundspeed can be derived by calculating the distance travelled over a known time period.

Each of the green pins in Figure 2 depicts a recorded radar position. The recording stopped at about 1,200 ft AMSL, most likely due to the aircraft descending below radar coverage.

Site and wreckage examination

The accident site was located in a dense stand of trees, about 400 ft AMSL. The trees stood about 15–20 m high and straddled a creek line in a band about 50 m wide, with open areas of farmland on either side (Figure 3).

Figure 3: Area of accident site

Area of accident site

Source: Google Earth, annotated by the ATSB

The wreckage trail extended about 50 m from the initial tree impact point, until the final piece of wreckage, oriented in an east-west direction. There were several notable tree impact points, including trees that had been broken in half or completely felled by the impact forces.

Calculations of the tree impact damage heights indicated the final flight path angle was a descent of about 13°. The main wreckage came to rest at the base of a tree that was struck at a height of about 10 m.  

The aircraft structure was significantly disrupted as a result of impacting several trees (Figure 4).

Figure 4: Aircraft main wreckage at the base of a large tree that was struck

Aircraft main wreckage at the base of a large tree that was struck

Source: ATSB

The ATSB conducted an examination of the aircraft wreckage. This examination identified that:

  • the disruption to the aircraft and foliage, coupled with the length of the wreckage trail, indicated that the aircraft had significant forward speed at impact
  • the flaps were in the retracted position
  • the aircraft had no evident pre-impact defects with the flight controls or aircraft structure
  • the aircraft was intact prior to impact with terrain
  • the engine had no obvious defects upon external examination
  • the throttle setting was captured at an idle position during the accident sequence
  • the propeller rotational damage signatures were minimal, indicating a low power setting.

Ongoing investigation

The investigation is continuing and will include:

  • interviews with parties involved with the operation of the aircraft
  • further analysis of the radar data
  • examination of the pilots’ qualifications, experience, and medical/recent history
  • assessment of the aircraft’s flight performance characteristics
  • assessment of spin training requirements and practices
  • examination of aircraft maintenance and operational records
  • processes surrounding the use of flight notes or a nominated SARTIME to highlight expected arrival/return times so that aircraft are identified as overdue in a timely manner.

Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties so appropriate and timely safety action can be taken.

A final report will be released at the conclusion of the investigation.

__________

  1. A spin is a sustained spiral descent of a fixed-wing aircraft, with the wing’s angle of attack beyond the stall angle.
  2. Eastern Standard Time (EST) was Coordinated Universal Time (UTC) + 10 hours.
  3. Primary radar returns are produced by radar transmissions that are passively reflected from an aircraft and received by the radar antenna. The received signal is relatively weak and provides only position information, not the aircraft’s altitude.
  4. Secondary radar returns are dependent on a transponder in the aircraft replying to an interrogation from a ground station. An aircraft with its transponder operating is more easily and reliably detected by radar and, depending on the mode selected by the pilot, the aircraft’s pressure altitude is also displayed to the air traffic controller.
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Summary

The ATSB has commenced a transport safety investigation into the collision with terrain of a Cessna A150 Aerobat two-seat light aircraft near Cedarton, approximately 38 km south-west of Sunshine Coast Airport, Queensland, on 23 June 2021.

The aircraft was hired for a private flight to conduct aerobatics with an instructor pilot and another pilot on board. The aircraft departed Sunshine Coast Airport at 1103 and collided with terrain at about 1122. It was reported missing after failing to return to Sunshine Coast Airport during the afternoon. A subsequent search confirmed the aircraft had collided with terrain in bushland near Cedarton. The two pilots on board were fatally injured and the aircraft was destroyed.

The evidence collection phase of the investigation will include examination of the accident site and wreckage by ATSB investigators, and the collection of other relevant evidence, including recorded data and communications, air traffic control surveillance data, weather information, witness reports and pilot and maintenance records.

A report will be published at the conclusion of the investigation. Should a critical safety issue be identified during the course of the investigation, the ATSB will immediately notify relevant parties, so that appropriate safety action can be taken. 

General details
Date: 23 June 2021   Investigation status: Completed  
Time: 11:22 Australian Eastern Standard Time   Investigation level: Short - click for an explanation of investigation levels  
Location   (show map): 5 km WSW of Peachester, Queensland   Investigation phase: Final report: Dissemination  
State: Queensland   Occurrence type: Collision with terrain  
Release date: 10 August 2022   Occurrence category: Accident  
Report status: Final   Highest injury level: Fatal  

Aircraft details

Aircraft details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model A150M  
Aircraft registration VH-CYO  
Serial number A1500655  
Operator Sunshine Coast Aero Club Pty. Ltd.  
Type of operation Flying Training  
Sector Piston  
Damage to aircraft Destroyed  
Departure point Sunshine Coast, Queensland  
Destination Sunshine Coast, Queensland  
Last update 10 August 2022