Pilots and general staff at Aer Lingus are reacting angrily to the airline's latest industrial relations moves.
IALPA - the union representing pilots says a letter sent to its members today is a serious escalation in the row over Aer Lingus's new Belfast base.
The letter threatens to suspend any pilot who refuses to train staff at Belfast from tomorrow onwards.
Meanwhile SIPTU says it's not ruling out industrial action over Aer Lingus's decision to freeze pay increases because of the union's failure to agree on cost cutting measures.
Michael Halpenny of SIPTU met with Aer Lingus management this afternoon and said they fully intend to pursue the company by whatever means are necessary to ensure their members are paid their "due increases".