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| Date: | Monday 13 March 2017 |
| Time: | 22:09 |
| Type: |  Boeing 737-838 |
| Owner/operator: | Qantas |
| Registration: | VH-VZZ |
| MSN: | 39445/4010 |
| Year of manufacture: | 2012 |
| Fatalities: | Fatalities: 0 / Occupants: 184 |
| Aircraft damage: | None |
| Category: | Accident |
| Location: | near Canberra, ACT -
 Australia
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Perth Airport, WA (PER/YPPH) |
| Canberra Airport, ACT (CBR/YSCB) | |
| Investigating agency: | ATSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
At about 21:55 EDT a Qantas Boeing 737-838 aircraft was about to start its descent in to Canberra Airport. The aircraft was on a scheduled passenger flight from Perth Airport and had two flight crew, five cabin crew, and 177 passengers on board. The first officer was the Pilot Flying (PF) and the Captain was performing the role of the Pilot Monitoring (PM).
Air traffic control (ATC) cleared the flight to descend and advised its flight crew to expect an arrival on runway 17. The controller also requested that the crew maintain maximum speed. In response, a descent speed of 320 kt was selected, 40 kt above the standard descent speed of 280 kt. The aircraft’s maximum allowable operating speed (VMO) was 340 kt.
At about 22:00, the flight crew informed ATC that descent from flight level (FL) 310 had commenced and reported some light to moderate turbulence. Shortly after, ATC informed the flight crew that there would be a runway change to 35.
At about 22:04, the flight was descending past FL 280 when the flight crew made an announcement over the aircraft’s public address system advising the cabin crew to prepare for landing. That announcement provided a cue to the cabin crew that they had about 10 minutes to secure all loose items in the cabin before illumination of the ‘fasten seat belt’ sign. By the time the aircraft passed FL 270, it had accelerated to the flight crew selected speed of 320 kt.
At about 22:09, the turbulence began to increase. In response, the flight crew switched on the ‘fasten seat belt’ sign and advised the passengers and crew to be seated with seat belts fastened. The operator’s procedures required cabin crew members to be seated within 1 minute of that
announcement.
At that time, a cabin crew member was passing row 22 on her way back to the rear of the cabin. The aircraft’s movement due to the turbulence was such that she needed to hold onto the overhead lockers as she walked along the aisle. About 15 seconds later, she reached the rear galley, closed a stowage latch, and secured a rubbish bin in preparation to be seated in the left cabin crew seat.
When the flight descended through FL 220 (about 30 seconds after the ‘fasten seat belt’ sign was switched on), the wind direction changed by about 80 degrees, resulting in a head wind increase from 15 kt to 32 kt. That in turn led to the airspeed increasing through 325 kt, and the PF applying control column backpressure to avoid exceeding VMO. About 1 second after the maximum control column force was applied, the autopilot disengaged and the G-Load4 peaked at 2.2 g. The pilot monitoring reported that they were checking the instrument approach, as a result of the change to runway 35, when they heard the autopilot disengage tone and saw the speed of the aircraft increasing toward VMO.
The aircraft’s pitch angle changed by 3.87 degrees in 1 second, and its airspeed reached a maximum of 339.5 kt.
The cabin crew member recalled that, while standing in the rear galley and preparing for arrival, she felt the cabin floor drop and then quickly come up. The force due to the aircraft’s movement resulted in the cabin crew member fracturing her leg. The cabin crew member seated in the right rear seat assisted the injured cabin crew member.
The aircraft movement also resulted in a second cabin crew member in the forward galley falling forward and hitting her head on a trolley. She also received injuries to her knees, back and neck.
The flight crew received an interphone call from the cabin reporting the leg fracture injury. The turbulence subsided and the flight crew turned off the ‘fasten seat belt’ sign and first aid was provided to the injured crew members.
At about 22:11, the aircraft’s speed decreased and the flight crew re-engaged the autopilot. The flight crew alerted ATC to the turbulence and were informed that no other turbulence had been reported in the area.
Due to her fractured leg, the injured crew member in the rear galley remained lying on the cabin floor for the landing. The aircraft landed at about 22:34, and paramedics met the aircraft to attend to the two injured cabin crew members. Both of them were transferred to a hospital for treatment.
The cabin crew member injured in the rear galley was admitted to the hospital. The other crew member was treated and discharged without admission. The aircraft was not damaged and none of the other crew or any of the passengers were injured.
Findings
- The increase in headwind while VH-VZZ was making a routine high speed descent at 320 kt resulted in the airspeed increasing towards the aircraft’s maximum allowable speed.
- The pilot flying applied a control column input to prevent an overspeed, which resulted in the autopilot unexpectedly disengaging. The consequent change of pitch and g-loading led to two cabin crew suffering injuries.
- The aircraft’s autopilot had been modified such that, if sufficient control column back pressure was applied, the autopilot would disengage rather than revert to the Control Wheel Steering (CWS) mode. Autopilot disengagement resulted in larger elevator and pitch responses than those associated with reversion to CWS mode.
Accident investigation:
 |
|
Sources:
http://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-030/
History of this aircraft
Other occurrences involving this aircraft
| 14 October 2017 | VH-VZZ | Qantas | 0 | Sydney-Kingsford Smith International Airport, NSW (SYD) | |
min |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 15-Mar-2017 08:20 | Pineapple | Added |
| 04-May-2023 13:22 | harro | Updated |
Corrections or additions? ... Edit this accident description
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