Ryanair, which is one of Boeing’s largest customers, said in a statement that it had expected to receive delivery of 27 aircraft from September and December.

However, production delays at the Spirit SPR.N Fuselage facility in Wichita, Kansas, combined with Boeing repair and delivery delays in Seattle, meant the budget airline now expects to receive only 14 aircraft between October and December.

Flight cancellations will take effect from the end of October, and will be communicated to all affected passengers by email over the coming days, Ryanair said.

“At this early date, we do not expect these delivery delays will materially affect our full-year traffic target of 183.5 million,” Group Chief Executive Michael O’Leary said.

“But if the delays worsen or extend further into the January to March 2024 period, we may have to revisit this figure and possibly adjust it slightly downward,” he added.

Ryanair shares were down 2.8% at 1000 GMT.

Asked if it could confirm the delays and when deliveries would be up to date, a spokesperson for Boeing said that the planemaker valued its partnership with Ryanair and was committed to supporting the airline.

Ryanair already trimmed its full-year passenger forecast from 185 million in July, citing potential Boeing delays, as well as the impact of air traffic control strikes.

O’Leary consistently blasted Boeing throughout last year for delays that impacted deliveries up to its key 2023 summer season, but buried the hatchet in May with a multibillion-dollar deal for as many as 300 Boeing jets.

Ryanair executives had said deliveries had “significantly improved” before Boeing discovered a production flaw last month that has slowed deliveries of its best-selling 737 MAX aircraft.

Ryanair said it will cut three aircraft from those based at Charleroi airport in Belgium, two from Dublin and five from Italian airports, including Bergamo, Naples and Pisa. There will also be aircraft reductions at East Midlands airport in the UK, Porto in Portugal and Cologne, Germany, it said.

The airline had expected delivery of 57 Boeing aircraft between September 2023 and May 2024 and said it was working to try to accelerate deliveries in the January to May 2024 period so that it can enter the Summer 2024 peak travel season with all aircraft delivered as expected.

(Reporting by Conor Humphries, additional reporting by Yadarisa Shabong in Bengaluru and Padraic Halpin in Dublin; Editing by Nivedita Bhattacharjee, Sharon Singleton and Susan Fenton)