The Engineering, Printing and Manufacturing Union says it will be difficult to reassemble a team of skilled workers to upgrade Air Force Hercules aircraft if a troubled contract can be resurrected.
Defence Minister Wayne Mapp says the Government is close to a deal with American company L-3 Communications to revive the upgrade process.
Safe Air pulled out of its contract with L-3 this year and laid off 92 workers who were to do the job.
The union's head, Andrew Little, says recruiting a team won't be easy because the workers are scattered around the country and overseas and Safe Air's reputation as an employer has been tainted.
Mr Little says the Government, Safe Air and possibly the union will have to work out a recruitment strategy.
But Dr Mapp says he has been advised it will be possible to recruit the staff needed to do the job.
The Government is poised to reach a revised deal with L-3 over the upgrade of RNZAF Hercules aircraft if an agreement can be reached on price. A $226 million budget was approved by the previous government in December 2004.
Under a proposed deal, the Ministry of Defence says the Government would do structural work on the aircraft, but L-3 would retain technical responsibility for the project.
The two parties have to agree on how much should be deducted from L-3's contract if the Government does much of the work itself.
The work would be carried out at the Woodbourne base of Safe Air, a subsidiary of Air New Zealand.
The project is years behind schedule because of technical and contractual difficulties.
It was designed to extend life of the Hercules aircraft, which have been with the air force since mid to late 1960s, and upgrade the software on them.
The work is in two parts: modern navigation software and flight deck communications systems and structural refits to extend the life of the aircraft.
Work on the first two aircraft has already been done in North America and three aircraft remain.
Dr Mapp says the delays have caused difficulties and the upgrade could cost more.
As a small Defence Force, New Zealand should be buying proven, off-the-shelf equipment, Dr Mapp says.
But in this case, the Defence Force ended up being a pioneer in the development of new software technology for the upgrade.