The accident investigation revealed that the captain entered a left bank as his attitude director indicator (ADI) froze and showed no roll moment. He continued the bank as the copilot's ADI and the standby ADI both showed he was now banking excessively. The airplane's comparator warning system sounded to alert all concerned that there was a problem with at least one of the ADI's. Throughout all this the first officer said nothing. The flight engineer did call out the problem, but the captain ignored his warnings as well as those from the airplane. Less than 60 seconds from takeoff, they all died.
The failure in Crew Resource Management and the failure of both pilots to recognize an Unusual Attitude killed them both and their two crew mates. But why? The British Accident Investigation Board hints at a few answers:
There is another factor not mentioned in the accident report. Older aircraft the captain may have been familiar with would have self contained ADI's. That is, these ADI's were units unto themselves, not connected with any other equipment. If an ADI malfunctioned, the fault was more than likely to be in the ADI itself. Newer ADI's, such as the one installed on this Boeing 747, often get their attitude information from Inertial Reference Units (INUs). Pilots can easily cross train from one aircraft to another and not have a firm grasp of this idea. Had this captain understood that a little better, he might have properly diagnosed the problem.
Sitting in the left seat brings with it several responsibilities, among which is the need to stay sharp and avoid complacency. The best way to do that is to stay in the books and invite critique from others on the flight deck; but if you shut them down that opportunity is lost.
Everything here is from the references shown below, with a few comments in an alternate color.
Photo: HL 7451, from Aviation Safety Network.
This was a textbook response as would have been called for in the aircraft flight manual and by standard unusual attitude recovery procedures.
More about this: Unusual Attitudes.
The investigators point out the pushed back pin was likely to have occurred during installation and since the ADI had been working normally until the previous flight, it was unlikely to be the cause of the problem.
May Day: Bad Attitude, Cineflix, Episode 79, Season 11, 20 January 2012 (Korean Air 8509)
United Kingdom Air Accidents Investigation Branch, Aircraft Accident Report 3/2003, Report on the accident to Boeing 747-2B5F, HL-7451, near London Stansted Airport on 22 December 1999
Copyright 2019. Code 7700 LLC. All Rights Reserved.