The Irish budget carrier has 135 Maxs on order, but was forced last year to reduced planned capacity growth by 4% due to the Max grounding.

Boeing has since said the Max may not now return to service until “mid-2020”.

In a memo to staff, chief executive Eddie Wilson said Ryanair had hoped to have 10 Maxs operational by June 2020.

However, it has been forced to remove these from its flight schedule due to the ongoing grounding. Wilson added that based on Boeing’s estimate, Ryanair did not expect to start taking deliveries of its Maxs until the autumn.

“We cannot rule out further base cuts and closures,” said Wilson. “We will do our best to avoid any more base closures, but this will mean eliminating at least 10 aircraft from existing bases so further pilot and cabin crew jobs losses cannot be ruled out.”

Wilson added the airline would aim to advise all bases by early February what further cuts or closures will be required, adding they would be as a direct result of the Max delays.

Meanwhile, Ryanair has inked a four-year labour agreement with Irish pilots union Forsa, which it said would deliver a new pay structure and roster.