Paul Lewis/SINGAPORE
A US lawsuit filed against Sundstrand has called into question the reliability and effectiveness of the company's Mk2 ground proximity warning system (GPWS), following the fatal crash of a Garuda Indonesia Airbus A300B4 in Sumatra a year ago.
The Chicago-based Nolan Law Group, representing the family of two deceased US passengers, alleges that the Sundstrand GPWS "-was defective in that it did not sound or provide any warning to the pilot of flight GA152 that the airplane was on a collision course with the ground". The crash, near Medan on 27 September, 1997, killed all 234 people aboard.
In seeking wrongful death damages from the US company, Nolan alleges that the GPWS was "not reasonably safe, and defective when used" on account of the the fact that the system's radar altimeter failed to detect fast rising land, it included no digital terrain reference or cockpit visual terrain display and was sold without either "adequate instructions" for inspection, testing, maintenance and repair or warnings on unsafe use.
A final report on the crash is not expected before early 1999 on account of Indonesian crash investigators giving priority to the 19 December, 1997, SilkAir Boeing 737-300 accident also in Sumatra. Unlike the SilkAir crash, investigators say that the Garuda crash has yielded "clear" cockpit voice and flight data recordings right up to the point of impact.
Sundstrand, which has sold its GPWS business to AlliedSignal, was unable to comment.
Investigators have refused to comment on whether the 200 parameters recorded included a GPWS alert or not. Sources close to the investigation have told Flight International, however, that the crash was the result of an "accumulated chain of events involving weather, communications internally and externally and, maybe, systems".
The aircraft was making a radar vector approach to Medan in poor visibility when the pilot failed to turn right and intercept the instrument landing system as the result of apparent miscommunication between the cockpit and air traffic control. The A300 flew into a mountain valley and, according to crash site observers, appeared to be attempting a last-minute turn when it hit ground more than 500ft (168m) below its last cleared height of 2,000ft.
Sources suggest that the position of the flap screws indicate that the aircraft may have been in a landing mode, which would have inhibited the GPWS sounding. Enhanced GPWS, now entering airline service, includes a terrain database to overcome radar altimeter shortcomings and provide earlier warning of rapidly rising ground.
Meanwhile, a New York federal court judge is due to consider the status of a $25 million suit against Boeing on 5 October arising from the SilkAir crash.
Source: Flight International
