Video report by ITV News Correspondent Juliet Bremner
Ryanair said it expects to cut 3,000 jobs, including pilots and cabin crew, from its workforce.
The budget airline announced a restructuring programme which could involve unpaid leave and pay for workers cut by up to 20 per cent.
It says it will stop operating at a "number of aircraft bases across Europe" until demand for air travel recovers from the coronavirus pandemic.
Chief executive Michael O’Leary, whose pay was cut by 50 per cent for April and May, has agreed to extend the reduction for the remainder of the financial year to March 2021.
Ryanair said its flights will remain grounded until “at least July” and passenger numbers will not return to 2019 levels “until summer 2022 at the earliest”.
It expects to operate fewer than one per cent of its scheduled flights between April and June, and carry no more than half of its original target of 44.6 million passengers between July and September.
The firm expects to report a net loss of more than 100 million euros (£87 million) between April and May, with "further losses" in the following three months.
In a statement, the company said: "Ryanair entered this unprecedented Covid-19 crisis with almost 4 billion euros (£3.5 billion) in cash, and we continue to actively manage these cash resources to ensure that we can survive this Covid-19 pandemic, and more importantly the return to lower fare flight schedules as soon as possible.
"Our customers can look forward to more low air fares as we are forced to compete with flag carrier airlines who have received 30 billion euros (£26.2 billion) in state aid 'doping' to allow them to sustain below-cost selling for months after this Covid-19 crisis has passed, as it certainly will over the coming months."
Chief executive Alison Rose said: "Every person, family and business has been affected by the current situation and normal business activity has been severely impacted.
"We are putting our purpose into action and I am proud of how we have responded, providing our customers, communities and colleagues with the support they need.
"Although the outlook remains extremely uncertain, we approach the crisis from a position of strength, with confidence in our balance sheet and focus on our strategic priorities."
It remains unclear how many of the job losses will be in the UK.