The defence minister must intervene to save the future of aircraft specialists at Denel Aviation, trade union Solidarity said on Tuesday.
"We demand that the minister of defence intervene and convene a meeting... thereby give a definite answer to the employees, who are at present facing the festive season not knowing what their fate will be," spokesman Jack Loggenberg said.
The defence department gave notice in June last year that it would cancel its contract for aircraft maintenance with Denel Aviation/AMG.
Negotiations were held to amend and possibly review the contract, but in November the air force said it would not be going ahead with the new contract with Denel Aviation/AMG after March 31, 2013.
There was now renewed uncertainty over the jobs of 523 aircraft specialists at Denel Aviation/AMG.
Loggenberg said Denel Aviation/AMG met with SA Air Force Chief Major General Zakes Msimang last week. The union was informed the air force would "definitely" not be renewing its contract because of its financial position.
He said Solidarity had not yet received a formal section 189 notice to indicate that those who worked at various air force squadrons across the country would be retrenched.
If a certain number of the technicians would be utilised by the air force, a section 197 notice had to be issued for the transfer of contracts of service, he said.
There was also uncertainty over who would be responsible for the employees' severance packages.
"In accordance with the contract, the SA Air Force is responsible for the severance packages. It is uncertain whether the air force will, in fact, be responsible for retrenchments and subsequently, the severance packages, once the contract has expired," said Loggenberg.
"Denel Aviation/AMG maintained that the air force would still be responsible for paying the severance packages. Our concern is that more retrenchments could follow at Denel Aviation/AMG should it pay the severance packages. Denel has just gone through restructuring."
Denel spokeswoman Sinah Phochana said: "Denel is currently in discussions with the South African Air Force on the AMG contract matter. We will issue a statement on the outcome of the discussions once they have been concluded."