Two new Boeing C-17 aircraft will set back the New Zealand Defence Force at least $600 million, the Government has been advised.
The Boeing C-17 Globemaster is being considered as a replacement for the aging fleet of Hercules C-130s, some of which are nearly 50 years old.
Members of the Foreign Affairs and Defence select committee took one of the Australian Defence Force's C-17s for a test run in February.
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In a report released last week, the committee said that the cost of two of the C-17s would be "a minimum of $600 million, with an operating cost of $20,000 per hour".
It said the C-17s would be a "desirable acquisition" and noted that there were only eight to 10 of the aircraft left for sale.
MPs on the committee sought advice on how money could be found to purchase the aircraft and whether it was practical to replace five Hercules with two Globemasters.
"We learned that the purchase has been provided for in the Defence Midpoint Rebalancing Review, and the possibility of making the funds available earlier is being considered," the report said.
Secretary of Defence Helene Quilter told the committee that any purchase of C-17s might not be a "complete replacement" for the Hercules and the two types of aircraft could possible operate side by side.
The Ministry of Defence was analysing information from Boeing on the price and availability of the aircraft, and it was also working with its Australian counterparts to determine whether it would offset some of the C-17's operating costs.
Around $50 million of the $300 million price tag was believed to be for operating costs and replacement parts.
Defence Minister Gerry Brownlee said last month the C-17 was one of several large military aircraft being considered to assist with the Defence's Force airlift capacity.
Mr Brownlee said any decisions about military acquisitions needed to be made carefully.
He said the NH90 helicopters purchased by the previous government for $770 million had proven to be a "challenging piece of kit" because they were difficult to transport.
The minister made the comments after the NZDF was unable to take the NH90s to Vanuatu after Cyclone Pam because they were not cleared for island-hopping and were vulnerable to sea spray if transported by ship.
The NH90s are currently being used in a search and rescue training exercise in Marlborough.
Air Force chief Mike Yardley said they were a "highly capable aircraft".
"This aircraft is well suited to the wide range of work the Air Force carries out with Police, Civil Defence and the Department of Conservation," he said.
Unlike the Hercules, the C-17 had capacity to transport an NH90-sized helicopter.