Qantas has issued a safety information notice to its pilots after an accident left two cabin crew members injured.
On 13 March, 2017, a Qantas Airways Boeing 737 was travelling to Canberra on a scheduled passenger flight from Perth Airport, Western Australia. There were two flight crew, five cabin crew, and 177 passengers on board.
As the aircraft began descending towards Canberra Airport, it encountered increasing turbulence, and the flight crew switched on the ‘Fasten Seat Belt Sign’, calling for cabin crew members to be seated within one minute of the announcement. The crew began to move towards their seats, securing the cabin as they went.
At 22,000 feet, an abrupt change in the direction of the wind resulted in the aircraft airspeed increasing towards the maximum allowable operating speed.
To prevent an overspeed, the pilot flying applied backpressure on the control column, so as to override the autopilot. This was a common practice for B737 flight crews at Qantas, and the first officer recalled that this was part of initial training for the B737. The expected outcome was that the autopilot would revert to a different mode and raise the aircraft’s nose.
A cabin crew member who had not yet reached her seat felt the cabin floor drop and then quickly come up
In this case, however, the autopilot disengaged, and the aircraft moved abruptly. A cabin crew member who had not yet reached her seat felt the cabin floor drop and then quickly come up. The force of the aircraft’s movement resulted in her fracturing her leg, while a second cabin crew member fell and hit her head on a trolley.
The injured crew member was given first aid and the aircraft landed without further incident. Paramedics met the aircraft to attend to the two injured cabin crew.
The method of intervention by the pilot was understandable, and consistent with previous responses of other flight crew in similar situation. Modification of the autopilot, however, had inadvertently left the aircraft vulnerable to this type of scenario.
Qantas has taken steps to address the dangers that this manoeuvre can create. They have issued a safety information notice, warning of the potential dangers of that approach.
The report also highlights the manufacturer’s preferred use of speedbrakes to prevent overspeed. Boeing has advised that they are considering a revision to the overspeed guidance in the 737 flight crew training manual.
“It’s encouraging to see organisations taking steps to address problems as they emerge,” said Nat Nagy, the ATSB’s Executive Director, Transport Safety. “This method of intervention to prevent overspeed had been used 20 times in the past six years, but this occurrence and the resulting investigation has provided an opportunity to make transport even safer.”Last update 02 May 2018