The Community and Public Sector Union applied to the Fair Work Commission on Friday afternoon for an urgent re-listing of its dispute with Airservices Australia, saying it would apply for an interim order restraining dismissals from taking place if it was not provided full details on the positions to disappear.

Airservices chief executive Jason Harfield told staff at the air traffic control agency on Thursday it would be making 523 offers for voluntary redundancies, knocking back 138 applications as it sought to hold onto those on operational rosters.

CPSU deputy national director Rupert Evans said Airservices had failed to give details on the specific positions set to be cut and the reasons for them, as required by industrial law.

"The importance of that information is it allows us to look at who would be left in various areas and whether there's capacity for that work to be done, which can lead to health and safety issues for the workforce, and of course subsequent aviation safety concerns which may arise for not having enough people," he said.

Mr Evans said Airservices had also breached the enterprise bargaining agreement by failing to give those offered a voluntary redundancy four weeks to decide, instead giving them half that time.

An Airservices spokesman said on Saturday the agency had engaged in ongoing consultation with employees and unions regarding the design and implementation of the VR program, and "look[ed] forward to any further constructive consultation if necessary in the Fair Work Commission".

Mr Harfield earlier addressed the potential for safety dangers in relation to the major restructure, saying a detailed and rigorous process had been followed after the "strong level of interest" in departing the corporation.

"Every VR application [was] assessed individually to determine any potential impact on the safety of our air traffic control or aviation rescue fire fighting operations," he said.

"This process saw our senior leaders identify actions which need to be completed prior to individuals departing the business, while in some instances VR applications were declined where risks were identified."

There were 107 staff ruled to be ineligible largely because they were on an operational roster, with another 31 ineligible due to the requirement for their role or capability at the agency, or having withdrawn their expression of interest, Mr Harfield said.

Corporate-services staff were the focus of the cuts. An Airservices spokesman said the majority of staff offered voluntary redundancies were in Melbourne, Brisbane and Canberra, cities which accounted for two thirds of the total workforce.

"Operational and rostered" air traffic controllers and aviation rescue fire fighters were not eligible for the redundancy payouts, and these services would continue to be delivered safely, a spokesman said.

Mr Evans said Airservices declared in a letter on July 11 that intended cuts to the agency's corporate sector were not expected to be achieved through voluntary redundancies alone. Professionals Australia, which also represents some staff, have said an extra 300 jobs were expected to be targeted, but an Airservices spokesman said there were no pre-determined numbers for staff reductions.

Formal VR letter offers and redundancy calculations would be all delivered by July 29.