The Engineering, Printing and Manufacturing Union says the Government needs to take some responsibility for skilled workers leaving the country.
The Christchurch Engine Centre, which is co-owned by Air New Zealand and Pratt Whitney, proposes to close a working line, which could result in up to 40 jobs being lost.
The EPMU says the line became unprofitable because of the high New Zealand dollar and a reduction in clientele.
Assistant director Strachan Crang said he would like to see more support from the Government.