Serious air traffic safety concerns have been raised by aviation workers over plans to axe 900 jobs at Airservices Australia, the organisation controlling skies at the country's major airports.

Key points: The cuts would reduce Airservices' workforce by almost a quarter

The cuts would reduce Airservices' workforce by almost a quarter Aviation experts say their concerns have fallen on deaf ears

Aviation experts say their concerns have fallen on deaf ears Airservices insists the cuts will only affect back room support staff

The concerns have been raised by air traffic controllers employed by Airservices, as well as pilots.

Unions representing the workers who are likely to be affected are seeking an urgent Fair Work Commission hearing to stop the job cuts.

Lawyers from the CPSU, ETU and Professionals Australia are requesting an immediate suspension of the Accelerate program, which will see a reduction of Airservices' workforce by almost a quarter over the next year.

Airservices, the government-owned organisation responsible for air traffic control, airway navigation and emergency services for airports, insists the cuts will only affect back room support staff.

However, the ABC has spoken to several Airservices insiders and aviation experts who claim that despite repeated attempts for clarification about how the Accelerate program will affect the security of the nation's skies, their concerns have fallen on deaf ears.

"We haven't seen any of the safety work that's being done to justify this being a safe course of action" said Melbourne-based air traffic controller Tom McRoberts.

"Airservices say they've done it all but we haven't seen any."

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Mr McRoberts, who has more than a decade's experience working as an air traffic controller and is also president of Civil Air, fears the engineers responsible for keeping aeronautical equipment in working order could be among those facing redundancies.

"[They are] taking guys away from being able to fix my radar if the radar falls over. I'm yet to see any documentation to say that's a good thing," Mr McRoberts said.

Cuts only affect back office, technical staff: Airservices

But a spokeswoman for Airservices said that it had engaged in comprehensive consultation with the industry prior to announcing the job cuts, which would only affect back office and technical staff.

"We are not reducing the size of our operational and rostered air traffic control or aviation rescue firefighting staffing," the spokeswoman added.

Earlier this year, an ABC investigation revealed serious malfunctions in radar systems operated by Airservices Australia which led to some planes briefly disappearing from Sydney Airport's tracking system.

The CPSU is one of the unions calling for an urgent meeting in Canberra to address employees' concerns.

"When you get multiple faults happening that's where you get into trouble. So being able to fix faults as quickly as possible is really important," said CPSU president Alistair Waters.

"That's why those highly skilled technical staff are just so critical.

"One of the reasons why you absolutely need to have very high standards and low risk margins in aviation is because when you're talking about aviation risk, you're talking about catastrophic risk."

Some pilots have also approached the ABC, expressing outrage at Airservices for their lack of consultation about the Accelerate program and what it will mean for Australia's air traffic network.

Pilots group brands planned cuts 'utterly disgraceful'

The Aircraft Owners and Pilots Association of Australia (AOPA), which represents over 3,000 general aviation pilots, is calling for the resignation of Airservices chief executive Jason Harfield.

"It's utterly disgraceful ... I find it almost incomprehensible that the senior executive team of this billion-dollar organisation have not been able to secure the futures of these people who they are now asking to leave," AOPA's executive director Ben Morgan said.

"The people that are going to feel this the most are the low end. This is going to be another exercise in the top end of the organisation band-aiding their problems and their mistakes by asking the people at the bottom end of the chain to sacrifice their day-to-day work."

The unions' dispute was lodged with the Fair Work Commission last Friday.

They are claiming that up to 40 workers are being pressured to move from enterprise agreements to individual contracts, or else face involuntary redundancies.

During a combative Senate Estimates hearing on October 17, Mr Harfield told the committee that some workers would be moved into leadership positions as a result of the restructure and these roles were typically covered by individual contracts.

An Airservices spokeswoman told the ABC that every application for a voluntary redundancy, or consideration of an involuntary redundancy, would be assessed individually to determine "any potential impact on the safety of our air traffic control or aviation rescue fire fighting operations".

"Appropriate actions have been taken to ensure that the implementation of the Accelerate program is managed in a way that assures operational safety is considered throughout the life of the change program," the Airservices spokeswoman said.

Airservices began providing routine safety assurance reports to the aviation regulator CASA regarding the progress of Accelerate program last May.