Ryanair's chief operations officer will leave the company at the end of the month, the airline has announced.
Michael Hickey's resignation comes after the cancellation of tens of thousands of flights through to March next year because of errors in how pilots are rostered for work, disrupting the travel plans of 700,000 passengers.
Ryanair boss Michael O'Leary said Mr Hickey, who has had a 30-career with the airline, will continue in an "advisory role".
"Over the past 30 years Mick Hickey has made an enormous contribution to Ryanair, especially the quality and safety of our engineering and operations functions," he said.
"He will be a hard act to replace, which is why we are grateful he has agreed to continue in an advisory role to smooth the transition to a successor and to complete a number of large projects he is currently working on including a multiyear engine maintenance contract and new hangar projects in Seville and Madrid."
Mr Hickey will be the first executive to leave the embattled airline following the scheduling fiasco.
The company was already coming under heavy fire for cancelling up to 50 flights a day in the middle of September before an extra 18,000 flights were axed at the end of the month.
Ryanair said the cancellations were brought about because of an error with pilot holiday rosters and insisted the latest reduction in its schedule will "eliminate all risk of further flight cancellations".