Trade unions are seeking urgent meetings with Aer Lingus management over plans to cut up to 500 jobs.
The airline says it is currently operating less than 5% of its normal schedule, and has "no certainty" regarding the restoration of services or the future demand for travel.
It also says the situation is "exacerbated" in Ireland by the 14-day quarantine requirement for arriving passengers.
Unite regional officer Willie Quigley has written to airline management seeking an immediate meeting.
He claims the company has unilaterally 'lapsed' its COVID-19 Recovery Plan and moved to forced implementation of changes and layoffs.
He said these actions have created a huge amount of anger among members, along with a high level of mistrust of management.
"Any unilateral action will undermine the company’s prospects for recovery as we emerge from the pandemic.
"Aer Lingus appears intent on tearing up the industrial relations practices which have been developed over decades and contributed significantly to the company’s success.
"The Craft Group of Unions has written to Aer Lingus management seeking an immediate meeting and we look forward to an early reply and meaningful engagement with the company".
SIPTU is also calling for an urgent meeting in light of the planned cuts.
Its aviation sector organiser Neil McGowan said the announcement "has shocked and upset" its members.
"Representatives will seek to ensure that the as many jobs as possible are maintained at the airline and that any workers who choose to exit the company do so on a voluntary basis.
"The airline must engage with the union immediately and in addition to limiting the numbers exiting and maintaining employment in the airline, management must also step back from the planned lay-offs and further pay reductions it announced earlier this week."