Aer Lingus has been accused of attempting to frighten cabin crew into submission with threats to sack them as a row over rosters escalated.
Impact trade union also claimed the airline was trying to divide a unified group of workers who were determined to protect their working conditions.
Almost 150 Aer Lingus staff have been removed from the payroll over the last five days as cabin crew refuse to co-operate with new rosters.
The carrier has hired in several aircraft with crew, including from rival Ryanair, to ensure a full schedule will operate over the weekend.
Enda Corneille, Aer Lingus commercial director, warned cabin crew who refuse to operate the controversial new rosters could be sacked.
Impact, which represents 1,100 cabin crew, most of them working for Aer Lingus, said management were misjudging the mood of staff by issuing threats to sack them.
Earlier 280 cabin crew in uniforms marched to Aer Lingus headquarters at Dublin Airport to deliver a letter to the company's chief executive Christoph Mueller.
The suspended workers stated they remained ready, willing and able to work and loyal to Aer Lingus, but were also "loyal to each other and to our families whose quality of life we are trying to protect".
Impact maintains controversial aspects of the rosters include how duties can be changed by three hours on the day of duty, making it impossible to plan childcare; the introduction of "double" shifts and the removal of meal breaks from European flights. Cabin crew can be sent to work away from base for 26 days at a stretch, it claimed.
But airline bosses said the sole responsibility for the cancellations lies with union members for taking industrial action after 15 months of "negotiation, agreement, clarification, conciliation and binding arbitration".