The aircraft, registration a de Havilland Canada DHC-8 Dash 8, was manufactured in Canada in 1986.
Accident
During the approach to a right turn which would place the aircraft on final approach to runway 25, the rightlanding gear failed to fully extend so the co-pilot began to manually extend it using a hydraulic pump. The aircraft's power settings had already been reduced to Flight Idle which was normal, but the aircraft was inadvertently allowed to descend too low toward the undulating terrain leading into Palmerston North. The initial impact with terrain occurred at above sea level; an aircraft on profile should have been above sea level. Although Flight 703's Ground Proximity Warning System sounded an alarm four seconds before the aircraft hit the ground, the crew was unable to avoid the accident. According to the Transport Accident Investigation Commission report, an audio alarm telling the crew to climb the aircraft should have sounded 17 seconds before impact, but the GPWS malfunctioned, for reasons that have never been determined. There was an investigation by the New Zealand Policein 2001 into whether or not a mobile phone call from the aircraft may have interfered with the system. The official crash report does mention the following on page 69:
"The aircraft manufacturer's avionics representative advised that there was no likelihood that the operation of a computer, other electronic device or a cell phone would have affected the aircraft's flight instruments."
The captain's defence was that 4.5 seconds before impact the radar altimeter display flipped 1,000 feet in altitude as he watched.
Crash site
Flight 703 pancaked onto a hilltop and broke up as it slid along the ground, killing the flight attendant instantly. Passenger Reginald John Dixon tried to free two others trapped near the wing root as the wreckage caught fire. He failed to free them and a flash fire critically burned him. He died from his injuries two weeks later. Thus, three passengers also died and many others sustained injuries. of the accident aircraft For his bravery in a dangerous situation, Dixon was awarded the New Zealand Cross, New Zealand's highest award for civilian bravery.
Possible radar altimeter malfunction
Later study of the wreckage of Flight 703 revealed that the antennas for the radar altimeter had been painted and this possibly reduced the GPWS' ability to provide a timely alarm, although later comments by TAIC insisted the paint did not block or reflect signals. Radar altimeter antennas are clearly embossed with the words, "do not paint", a warning that was not heeded. Bench testing of the radar altimeter proved the unit was still functioning perfectly after its recovery from the wreckage.
