Aer Lingus has accused the pilots unions IMPACT and the Irish Airline Pilots Association of obstructing their plans to set up a new base in Belfast to protect their members' interests.
Earlier this week, the pilots responded to Aer Lingus' proposals for staffing its proposed new Belfast base.
The pilots want all recruitment done via Dublin, with staff then seconded to Belfast.
The unions say all collective agreements which currently apply in the Republic should also apply in Belfast and also want all contracts and disputes regarding Belfast to be governed by Irish laws.
They want all pilot vacancies to be notified to pilots currently on what they call the merit based seniority list at the airline.
In a letter to the unions, Chief Executive Dermot Mannion said IALPA is effectively proposing resolving the problems about establishing the Belfast base by not actually establishing the base.
He said IALPA's desire that all recruitment should take place via Dublin would deny equal job opportunities to local candidates in Northern Ireland.
Captains positions would be confined to the current Dublin pilots.
He says that not only would the pilots' proposals import existing restrictive practices into Belfast, but it would add additional ones.
Mr Mannion said the result would be not a Belfast base, but a contrived convoluted arrangement, where the protection of pilots would be measured by the inefficiency of the operation.
IALPA sources said they could not comment yet as members of their Executive were abroad flying and had not yet seen Mr Mannion's letter.
IMPACT Assistant General Secretary Michael Landers said that as it received the documents shortly before it was released to the media, it was clear that Aer Lingus' main purpose is not a genuine attempt to resolve these issues.
Mr Landers said IMPACT would be responding to the document directly to the company.
He said they would not be releasing their response to the media as they do not believe this is a sensible way to do business.
They will respond when their Executive has had sufficient time to consider today's letter.
