Ryanair CEO Michael O’Leary apologized during the company’s annual general meeting on Thursday for mass flight cancellations due to what the airline attributed to a failure in its pilot scheduling functions. Ryanair has canceled 2,100 flights over a six-week period in September and October to compensate for a shortage of pilots on standby caused by a miscalculation in annual leave.

In an effort to compensate for the staffing shortfall, Ryanair has offered its captains bonuses of €12,000 and first officers €6,000 to work more days. It has also asked its non-unionized pilots to forego taking all of their vacation days until next year. However, pilots at several of the airline’s bases have rejected the offer, and some have threatened to stage a campaign of “mass sick days.”

Meanwhile, the UK Civil Aviation Authority has admonished O’Leary for his insistence during a September 18 press conference that Ryanair “would not be paying for flights on other airlines” and that flight compensation regulation EU261 does not prescribe any such passenger rights entitlement.  

“Whilst I appreciate that most Ryanair passengers will likely be rerouted on the same day on another Ryanair flight, many will not,” wrote CAA consumers and markets group director Richard Moriarty in a letter to O’Leary dated September 19. “The latter group of passengers may be better served by flying with a different airline (or indeed to or from a different nearby airport). The CAA’s view, which I set out in Annex 1 of my letter to you of 16 August, is that Regulation EC261 requires Ryanair to offer passengers on canceled flights alternative travel options, including flying with a different airline.

“Your statement yesterday runs contrary to our view and contradicts the assurances that we were given on this point by your legal team.”

Ryanair on Thursday said it expects by the end of the week to have re-accommodated or authorized refund requests to more than 95 percent of the 315,000 customers affected by the cancellations.