Report says poor crew management of the approach and incorrect GPS use caused twin turboprop to crash in Iran
The Aeromist-Kharkov Antonov An-140 crash near Isfahan, Iran in December 2002 was caused by procedural navigation errors by the crew, says the report into the accident. All 44 people on board died when the aircraft hit high ground during the night descent towards Isfahan airport.
The Scientific-Technical Commission of the CIS Interstate Aviation Committee (MAK) report concludes that the main causes of the crash were poor crew management of the approach, and incorrect use of the aircraft's GPS satellite navigation system. Although the twin turboprop was being flown by test pilots, it had been chartered to carry senior Ukrainian aerospace industry executives to a roll-out ceremony for the Iranian licence-built version of the type.
The crew were normally engaged on visual flight rules factory tests and had low recent experience in instrument meteorological conditions and long-range flights. For that reason, they carried a supernumerary navigator who had no workstation and was seated in the jump seat of the normally two-crew cockpit.
The report says the aircraft, its equipment and the airport's navigation aids were all serviceable as the new An-140 began its approach from a reporting point 110km (60nm) from destination. The crew had made earlier visits to the airport, but in Antonov An-74s with different GPS equipment.
The An-140's GPS is specified as "unsuitable for approach" and was set in navigation mode, but the crew were using it as the sole approach aid, and ignored published procedures.
The night approach to runway 26R, intended to be visual, took place in haze, and the crew decided they would turn left to intercept a distance measuring equipment (DME) arc of 10nm (18.5km), but they used the GPS - not the DME beacon - to achieve the intercept. The GPS read 9.5nm for more than 3min despite the fact the aircraft was tracking to approach the DME arc and intercept it, and hit a mountain 33km from the beacon.
MAK says the crew made a number of errors, including:
* failure to apply approach procedures;
* incorrect reliance on the GPS, in breach of its operational requirements and their rating for its use on approach;
* failure to use information from other installed navigation equipment;
* failure to seek an alternative approach when they realised the GPS could not be giving a realistic DME readout.
PAUL DUFFY / MOSCOW
Source: Flight International
