Regional flights could be affected if Aer Arann Express pilots vote in favour of industrial action over plans to make 12 of them redundant.
The ballot will close next Tuesday and if the IMPACT members vote for industrial action, it is likely to begin on September 19th.
IMPACT said yesterday the action would disrupt flights between Dublin and Cork, Derry, Donegal, Galway, Kerry, Knock and Sligo. The company currently employs 60 pilots.
The union claims the company has refused to talk to it about the redundancies.
IMPACT official Mr Michael Landers said: "We don't believe these redundancies are necessary. And we don't accept that pilots can simply be sacked without consultation and professional representation, particularly from a company that has just been given £32 million worth of State business."
He said the Government recently granted Aer Arann Express the contract to run five "public service obligation" routes.
An Aer Arann Express spokesman yesterday said the company had an excellent relationship with staff and did not engage in dialogue with third parties.