The Government wants to scrap the Air Force's ageing Hercules at the end of their renewed lifespan.
The first of five revamped planes was officially handed over on Thursday, five years after work began.
The $250 million upgrade programme has been dogged by delays and has already cost 100 jobs at Air New Zealand subsidiary Safe Air.
Work has yet to start on three other aircraft made in the 1960s but the Government believes it is possible that each plane can operate beyond a 10-year target once upgraded.
However, Defence Minister Wayne Mapp wants them gone when they reach that point, saying a review due for release shortly forecasts the need for a new fleet.