Public servants from the Civil Aviation Safety Authority (CASA) and the Environment Department are preparing to join industrial unrest.

The Fair Work Commission is expected to receive an application for a protected action ballot of CASA safety inspectors, engineers and pilots.

Their representative unions say they have waited almost a year for a new pay offer.

The union says staff they will not compromise passenger safety in the attempt to get their bosses to the negotiating table.

Fatigue management is one of the main concerns among CASA staff, who argue that they are already forced to work too many hours.

Meantime, union members at the Environment Department have voted to begin a campaign of industrial action.

The department's 2600 public servants were recently offered a 3.05 per cent pay rise over three years, but it is tied to targets and workplace reform.

The department’s Antarctic Division faces some of the biggest losses, with the Government asking them to give up allowances paid for their time on remote bases, which the CPSU says makes up much of the workers' pay.

Remote housing allowances for national parks workers are among the conditions facing the axe as well.

Union delegates have been talking to public servants as they arrive for work at the John Gorton Building in Parkes this week.