Misinterpretation of and miscommunication about a plume of flame and smoke from a Saab 340 regional airliner's left engine following an interrupted start-up resulted in the captain ordering an evacuation of the aircraft in which incomplete instructions were provided to the passengers, 2 passengers sustained minor injuries, and several passengers exited the aircraft with their bags.
An ATSB investigation report into the incident details that on 5 April 2022, the Regional Express operated Saab 340 was being prepared for departure at Melbourne Airport for a flight to King Island, with two flight crew, a flight attendant and 23 passengers on board.
During the engine start, a ground crew member prematurely disconnected the ground power unit from the left engine. Recognising the interrupted start, the captain initiated the interrupted start checklist, which included motoring the engine to purge residual fuel (rotating the engine by running the starter motor without supplying fuel).
"As part of the motoring process there was a plume of smoke and flame from the engine, which prompted the marshaller, who was unaware that that could be expected, to gesture to the flight crew that there was a fire from the left engine, and to shut down the engine," ATSB Chief Commissioner Angus Mitchell said.
"Due to the marshaller's repeated hand signals, the captain stopped the motoring, which meant that burning fuel remained in the engine, and as a result, the fire was not extinguished."
The captain subsequently shut down both engines and discharged the left engine fire extinguisher. They then ordered the evacuation of the aircraft, without communicating their observations or actions to the first officer prior, thus limiting the FO's opportunity to contribute to the identification and management of the situation.
At that time the flight attendant was using the public address system, and so the captain ordered the evacuation via four chimes. However, the flight attendant did not recognise the chimes as an evacuation signal and did not react to the command, and they remained unaware that an evacuation was required until the captain opened the flight deck door to communicate directly.
Then, when ordering the passengers to evacuate, the flight attendant provided limited instructions, and passengers in the emergency row did not open the right overwing exit, which delayed the evacuation.
"As they evacuated the aircraft, some passengers took their baggage with them during the evacuation, which increased the risk of injury and delays exiting the aircraft," Mr Mitchell added.
In all the evacuation, via the right front door only, took 4 minutes, and there were 2 reported minor injuries sustained during the evacuation: one passenger with a knee injury and another passenger with a grazed elbow.
Meanwhile, due to the nature of the problem not being communicated directly from the aircraft to air traffic control, the aviation rescue and firefighting service response was delayed by two minutes.
Mr Mitchell said the investigation highlights the importance of undertaking an informed and coordinated approach to decision‑making to ensure that the most appropriate action can be taken.
"The use of all available resources, including seeking input from other crew members, particularly in abnormal or emergency situations, assists in being able to positively identify the nature of a problem," Mr Mitchell noted.
"This occurrence also highlights the importance of the use of standard communications, including hand signals, to be able to effectively convey information, particularly in a potentially time-critical situation."
At an organisational level, the ATSB found that Regional Express did not provide flight crew or ground crew recurrent training to review the hand signals required to communicate with each other, including those used in an emergency.
In addition, although flight crew were required to notify ground crew if an evacuation was necessary, the operator did not provide guidance to ground crew on the actions to be taken in the event of an evacuation.
"A number of previous investigations have identified the importance of ground crew being aware of what happens during an evacuation and how they can potentially assist," Mr Mitchell concluded.
You can find here the report: Interrupted engine start and evacuation involving Saab 340B, VH-ZRK, at Melbourne Airport, Victoria, on 5 April 2022
