Ryanair's chief operations officer will leave the company at the end of the month, the crisis-hit airline has announced.
Michael Hickey's resignation comes after the cancellation of tens of thousands of flights through to March next year.
The disruption was sparked by errors in how pilots were rostered for work and impacted travel plans for 700,000 passengers.
Mr Hickey’s key responsibilities included scheduling shifts for pilots.
Ryanair boss Michael O'Leary, who has faced calls for his own resignation, 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."
The first wave of cancellations was announced in the middle of September, with 2,100 flights disrupted.
Then weeks later the company was forced to cancel a further 18,000 flights.