The trade union Impact has confirmed that a fifth pilot has been suspended by Aer Lingus for refusing to help in the recruitment of new staff for its Belfast base.
This came as the airline issued a fresh ultimatum to all its pilots, giving them until Monday to confirm that they will unreservedly engage with the setting up of the new base.
The letter from Aer Lingus Chief Executive Dermot Mannion tells pilots they will be suspended unless they comply.
Impact spokesperson Niall Shanahan says this is an act of madness, adding: "It will disrupt passengers, it's going to damage the airline's reputation and it's going to impact on shareholder value."
Mr Shanahan continued: "This heavy-handed and counter-productive approach being employed by the airline, to us, does not make any sense."