What happened
On December 20, 2009, a Boeing 737-33V, registration LN-KKD, was preparing for a scheduled flight from Stockholm/Arlanda to Nice, France. During the de-icing process on the apron, the aircraft's APU generator failed, causing the cabin's main lighting to extinguish and disabling the internal communication and passenger announcement systems.
As the crew began starting the right engine, short-lived flames appeared from the engine exhaust, and a small pool of fuel on the ground briefly ignited. Although the fire extinguished itself spontaneously, several passengers observed the flames and shouted that the aircraft was on fire. This triggered a sudden movement of passengers toward the exits. Because the cabin crew could not communicate with each other or the cockpit via the intercom, and because passengers were blocking the aisles, the forward cabin crew initiated an emergency evacuation.
The investigation
The Swedish Accident Investigation Board (SHK) examined the sequence of events leading to the evacuation, focusing on the breakdown in communication between the ground crew, flight crew, and cabin crew. The investigation looked into the technical failure of the APU generator, the lack of signaling from ground staff when disconnecting external power, and the effectiveness of the crew's emergency training. The inquiry also reviewed the passengers' actions, including the improper use of an emergency exit door and the delay in evacuation caused by passengers attempting to retrieve hand luggage.
Findings
- The ground crew disconnected the airport's electrical power supply without notifying the pilots.
- The failure of the APU generator left the cabin crew without the ability to use the intercom or the passenger address system.
- The cabin attendants were unable to control or prevent the course of events in the cabin when spontaneous calls about fire caused a passenger reaction.
- The evacuation was initiated by the cabin crew without the required signal to the Commander.
- Passengers hindered the evacuation by bringing personal belongings and by incorrectly placing a left-side window emergency exit door inside the cabin rather than outside.
- The lack of a headset connection between the ground crew and the pilots meant communication during pushback relied solely on hand signals.
Safety action
Following the investigation, the following recommendations were made to the European Aviation Safety Agency:
- Improve initial and recurrent training for crews regarding emergency situations on the ground, specifically focusing on scenarios where electrical failures disable internal communication systems.
- Expand methods for verifying that passengers understand emergency evacuation procedures, particularly regarding the use of emergency exits.