The Royal New Zealand Air Force's fleet of Iroquois helicopters is down to 11 operational machines as preparations continue for a new fleet which will begin to arrive later this year.
The air force has put two Iroquois helicopters in mothballs as it geared up for the new fleet but said they could be put back in the air at a moment's notice.
The fleet of 13 Iroquois helicopters was being replaced by eight NH90 machines. The first was expected to arrive this year with all the fleet in service by 2013. The new fleet would cost $771 million.
The air force originally bought 16 medium utility Iroquois helicopters with the first five arriving in 1966. None went to Vietnam but New Zealand pilots flew American Iroquois in the war.
One crashed in 1972, one in 1995 and one on Anzac Day this year, killing all three air force crew on board.
The air force considered upgrading the Iroquois fleet nearly 30 years ago but nothing happened.
The air force said some of the limitations of the Iroquois showed in East Timor between 1999 and 2002 and reinforced the need for urgent replacements.
An Iroquois could carry an underslung load of up to 1045kg, had a cruising speed of 195km/h and a maximum range of 682km with auxiliary fuel tanks.
It could carry nine passengers or five troops with full packs, or seven troops in light order and was armed with machine guns in either door.
The new NH90s could carry an underslung load of 4000kg, 19 passengers, or 12 fully equipped troops. They had a range of 800km and a cruising speed of 260km/h. They could also carry two machine guns.
The air force was also replacing its fleet of five Sioux training helicopters with five Agusta-Westland A109 light utility helicopters.
The Sioux were the first helicopters flown by the air force and were similar to the helicopters made famous by the MASH television series about the Korean war.