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The light plane which crashed at Whenuapai air base yesterday came perilously close to setting off a devastating explosion.
The pilot and owner of the home-built aircraft, Wayne Matthews, 62, and his passenger, Brent Baldwin, 46, both died on impact.
The Thorp S-18 hit the ground at the Royal New Zealand Air Force base at Whenuapai 2m from liquid oxygen stored under pressure in tanks.
The aircraft exploded into flames, which were licking the walls of the liquid oxygen storage building when air force fire tenders arrived within a minute.
Incident controller Wing Commander Richard Marshall heard the explosion of the aircraft hitting the ground from his home on the base about 500m away.
He raced on foot towards the pall of smoke and found the wreckage on fire and flames licking the liquid oxygen storage building.
Liquid oxygen is highly flammable when stored under pressure and some observers believe that, had it exploded, it could have flattened everything within 50m.
Wg Cdr Marshall said when he arrived he was immediately worried about the danger and ordered people back from the area in case there was a further explosion.
"We run exercises regularly and part of our planning is to think about the oxygen exploding.
"I immediately appointed a couple of senior officers on the scene to take charge and widen the cordon."
Wg Cdr Marshall said one of the bodies was on the ground beside the burning aircraft and the other was trapped and had to be cut out by firefighters.
"There was a big explosion. They were both badly burnt."
He said both men would have died on impact.
Mr Matthews, who retired from the air force in 1995 after 30 years' service, was the brother of police superintendent Neville Matthews, who returned from America late last year where he was New Zealand police liaison officer.
Mr Baldwin who also served in the air force, left several years ago to set up an information technology company.
The air force's own fire tenders, which are on duty 24 hours a day, were on the scene within a minute of the crash and were joined a few minutes later by civilian firefighters and police.
Wg Cdr Marshall, who had known both men for many years, said the aircraft clipped a building as it came down and exploded into flames.
A navy Seasprite helicopter flew over the likely flight path of the crashed aircraft today and took aerial photographs in the hope it would help in the inquiry, he said.
Civil Aviation Authority (CAA) air crash inspector Alan Moselen said it was too soon to say what might have caused the crash.
"It is very early stages and we simply don't have any information until I conduct that technical inspection."
Witnesses said the aircraft appeared to have turned sharply at low altitude but Mr Moselen said he could not say if that meant it had stalled because of pilot error or if there may have been a technical fault with the aircraft.
"That's all assumptions at this stage. I don't have enough information for me to make a call on that."
Poor weather meant he had yet to make a detailed examination of the wreckage.
"It is totally destroyed. The fire was quite intense," Mr Moselen said.
Both men were members of the Whenuapai Aviation Sports Club and club captain Dave Cogan said home built aircraft were a growing part of the aviation industry. The CAA was stringent in its inspections and certifications before they were approved to fly.
Mr Matthews had been flying for only seven or eight years but there was no reason to believe he was flying outside his capabilities.
"Wayne was a very skilled pilot," Mr Cogan said.
"His passion is flying and he was flying just about every second day. Every opportunity he would be out flying his aircraft."
"It is a shock to everyone. He is a very experienced pilot and we are all waiting to find out the results from Civil Aviation's investigation."
The Thorp S-18 aircraft would have cost about $100,000 to buy as a kitset, with another 1800 hours to put it together to flying standard.
Mr Baldwin was about to order a high-performance aircraft from America, he said.
- NZPA
