Ryanair is to ground the majority of its fleet in the next seven to 10 days and warned all flights could be stopped in April and May.
In the last week a swathe of European countries have closed borders and banned flights.
The carrier said in countries where the fleet is not grounded, “social distancing restrictions may make flying to all intents and purposes, impractical, if not, impossible”.
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For April and May, it expects to reduce seat capacity by up to 80%, but said “a full grounding of the fleet cannot be ruled out”.
The airline said it is taking “immediate action to reduce operating expenses, and improve cash flows”, including freezing recruitment and discretionary spending, and implementing a series of voluntary leave options, temporarily suspending employment contracts, and significant reductions to working hours and payments.
It said it has cash and cash equivalents of more than €4bn.
Chief executive Michael O’Leary said: “We are communicating with all affected passengers by email and SMS, and we are organising rescue flights to repatriate customers, even in those countries where travel bans have been imposed.
“Our priority remains the health and welfare of our people and our passengers, and we are doing everything we can to ensure that they can be reunited with their friends and families during these difficult times.
“Ryanair is taking all actions necessary to cut operating expenses, and improve cash flows at each of our airlines. Ryanair is a resilient airline group, with a very strong balance sheet, and substantial cash liquidity, and we can, and will, with appropriate and timely action, survive through a prolonged period of reduced or even zero flight schedules, so that we are adequately prepared for the return to normality, which will come about sooner rather than later as EU governments take unprecedented action to restrict the spread of Covid-19”.