DUBLIN (Reuters) – Ryanair Chief Executive Michael O’Leary is concerned about slippage in Boeing’s timetable to return the 737 Max to service, saying the number of jets available to him in 2020 could fall to zero.

“I am concerned that the MAX return to service keeps slipping,” O’Leary told a conference call with analysts.

Ryanair earlier this month cut the number of Max jets it plans to fly next summer from 58 to 30. O’Leary said that could fall to 20, 10 or zero, “which would significantly truncate our growth rate.”