The Howard government and air force chiefs ignored advice from defence officials in 2002 against rushing into the Joint Strike Fighter project amid concerns that too little was known about the aircraft's cost and capabilities.
Documents released under freedom of information reveal officials advised against signing up to the ''system development and demonstration'' phase of the JSF, which has been beset by delays, technical problems and cost blowouts.
The officials, from the department's Investment Analysis Branch, also recommended the government keep its options open in choosing Australia's future combat aircraft under the ''Air 6000'' program, rather than lock itself into the JSF, otherwise known as the Lockheed Martin F-35.
''An accurate assessment of the F-35's abilities, and thus the cost-effectiveness of the aircraft in meeting Air 6000 requirements, cannot be determined from the limited information provided by the (United States)'', the officials said in written advice dated March 2002.
The advice to the defence capability and investment committee, which consisted of top military brass, said it was ''not prudent'' to join the project at that stage, nor to lock into the JSF, ''given the concerns about the project''.
Yet just three months later, then defence minister Robert Hill and air force chief Angus Houston announced Australia would join the system development and demonstration phase with an initial $300 million outlay.
''We've decided to do that on the basis of advice from the air force that they believe it will meet the capability requirements … as a replacement for the FA-18 and the F-111,'' Mr Hill said. He also indicated the government was ruling out other bidders for the Air 6000 program, saying ''we're going into the development phase expecting it to lead to acquisition of aircraft''.
At the time, Mr Houston said the JSF would ''fit beautifully into the structure we're developing'', even though the officials had warned it was ''not possible'' to tell how the aircraft would replace the ageing F-111 and F/A-18 planes because of ''the paucity of information''.
All 51 JSFs in the US fleet had to be grounded temporarily last month after a crack was found in an engine component of one plane. Australia is due to take delivery of its first two JSFs from the manufacturer in 2014.
Former Labor defence minister Joel Fitzgibbon told Fairfax Media the chiefs were ''obsessed'' with getting the JSF and tried to thwart his plans to consider other planes.
He spoke of ''the disproportionate influence of those in uniform, both on the former government and the current government''.
Amid delays in the aircraft, Mr Hill's successor Brendan Nelson bought an additional 24 F/A-18 Super Hornet aircraft. The current minister Stephen Smith is considering buying another 24.
Mr Hill declined to comment.