The court hearing into the 1995 Ansett Dash-8 crash heard testimony yesterday from an American engineer via a live audio link from Seattle.
Donald Bateman told Palmerston North District Court that corrosion on the aircraft's radio altimeter aerial was the most likely reason there had been only a few seconds' warning before the plane hit the ground.
Mr Bateman, chief engineer of flight safety systems at Honeywell Corporation, was giving evidence on day four of a depositions hearing.
The hearing is to decide if Dash-8 pilot Garry Sotheran will face trial on manslaughter and injury charges.
The flight attendant and two passengers died on impact and a third passenger died later of injuries.
Mr Bateman, developer of the Ground Proximity Warning System (GPWS) used in the Dash-8 that crashed in the Tararuas, explained that the radio altimeter was the prime sensor for the system, which warns pilots if they risk hitting the ground.
He said any loss or interruption of the signal to the altimeter because of corroded aerials or connections was likely to cause a GPWS malfunction.
The aerial taken from the wreckage of flight 703 had been badly corroded inside, he said, and in his view it was unserviceable.
Mr Bateman told crown prosecutor Ben Vanderkolk that corrosion was the most probable cause of the system failing to give pilots enough warning.
But he conceded that the corrosion could have developed after the accident - because the aerial had apparently lain outside for several months before recovery.
- NZPA
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