Event Details

Title:Boeing 747-419, Air New Zealand ZK-NBU, failure of inertial reference units 300 nm north-east of auckland, 12 March 1997
Micro summary:A failure of a brake control system unit due to water contamination takes out the inertial reference unit data bus.
Event Time:1997-03-12 at 0032 NZDT
File Name:1997-03-12-NZ.pdf
Publishing Agency:Transport Accident Investigation Commission (TAIC)
Publishing Country:New Zealand
Report number:97-005
Site of event:
Latitude/Longitude:S34°30' E179°25'
Departure:Auckland International Airport, Auckland, New Zealand
Destination:Los Angeles International Airport, Los Angeles, California, USA
Airplane Type(s):Boeing 747-419
Flight Phase:Cruise
Operator(s):Air New Zealand
Type of flight:Revenue
Serious Injuries:0
Other Injuries:0
Executive Summary:On Wednesday 12 March 1997, at 0032 hours, Boeing 747-419 ZK-NBU was enroute from Auckland to Los Angeles as Flight NZ18. The Captain’s electronic primary flight display no longer displayed flight reference information and appeared blank. An internal failure within the brake system control unit, due to water ingress, in turn caused a fault with the inertial reference unit data bus supplying information to the Captain’s display. An alternate inertial reference unit was selected and it failed to supply the required information. The selection of a third inertial reference unit resolved the problem and the Captain regained his display. The two affected systems were turned off and the aircraft returned to Auckland without further incident. Safety issues discussed include the adequacy of the Quick Reference Handbook and the vulnerability of an inertial reference unit to an external fault. Safety recommendations were made on both these safety issues.
Learning Keywords:Systems - Braking Systems
Systems - Electrical
Systems - Navigation Systems


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