Executive summary
On Tuesday 12 September 2006 at 0727, flight NZ503, a Boeing 737-319 registered ZK-NGJ started its take-off at Auckland International Airport on a scheduled flight to Christchurch. On board were 2 pilots, 3 cabin crew and 96 passengers.
Partway through the take-off roll an electrical relay failed, causing a loss of battery bus power. The pilots identified an escalating number of electrical malfunctions after take-off and elected to return to Auckland. After landing, the aircraft started to slowly fill with smoke, so the captain ordered a ground evacuation of the aircraft. All passengers and crew exited the aircraft without injury.
The evidence available pointed to the failure of the relay being due to faulty manufacture, which led to the contacts within the relay deteriorating over its 7-year life to the stage they were unable to remain closed because of the vibration encountered during the take-off.
The operator had initiated actions to monitor the performance of the relay and establish more robust procedures for crews to identify and handle a loss of battery bus power.
The ground evacuation provided valuable guidance on the effectiveness of the operator’s crew resource management and emergency procedures training. Safety recommendations were made to the regulator to improve the effectiveness of ground evacuation procedures and to disseminate the lessons learnt from the event.
Related Recommendations
Ensure that the Chief Executive of Air New Zealand and other New Zealand operators of Boeing 737 aircraft review and enhance emergency training procedures. The review should include the positioning of all crew members on board for abnormal landings and possible evacuations, and the associated use of all appropriate emergency exits, the use of hand signals in emergencies and the management of the ground evacuation checklist to ensure that flap has been fully deployed.
Promote the lessons learnt from this incident, in particular the value of good CRM training and the use of resources.