Ryanair hoped a bonus payment could entice some pilots to change their holiday plans, but O'Leary then further inflamed the situation with disparaging comments about pilots at the airline's annual meeting in Dublin.
No response has yet been made public from Ryanair's pilots or unions who now represent a portion of them.
ONE OF RYANAIR'S most senior executives is to step down from his position as the airline attempts to rebuild after a damaging few weeks.
He also denied that he was referring to Ryanair pilots when he was recorded saying that pilots "get paid very well for doing what is a very easy job" last month, instead saying he was referring to unionised pilots in other airlines.
Mr Hickey's job was to schedule the pilots' shifts.
He concluded the message to pilots by asking them to give the airline any evidence of higher pay by a rival at their base so Ryanair could "meet it and beat it".
In the letter Mr O'Leary is said to have asked pilots not to abandon the company and offered them incentives to stay.
Ryanair announced its first wave of 2,100 cancellations in the middle of September, after it rearranged pilots' rosters to comply with new aviation rules requiring a change in how their flying hours are logged.
More than 700,000 passengers' travel plans have been affected by what Ryanair boss Michael O'Leary admitted was a "cock up".
As part of his role Mr Hickey, who has had a 30-year career with the airline, was responsible for scheduling shifts for pilots.
Passenger numbers jumped by 10% in September, even amid flight cancellations, which "underlines the extent to which the budget carrier is still growing despite the pilot-rostering challenges that have clipped its planned expansion", says aviation website FlightGlobal.
But passengers have complained about the short notice of the cancellations and the consumer group Which? said Ryanair's compensation information was "woefully short".