(Bloomberg) -- Ryanair Holdings Plc said delivery delays of 737 Max aircraft have worsened and are now likely to affect capacity next summer, as Boeing Co. grapples with supplier quality-control issues. 

Ryanair said last month that it expected to receive 14 of 27 aircraft due by late December, but that number could fall to as low as 10, Chief Executive Officer Michael O’Leary said in an interview at an airlines meeting in Brussels on Thursday. The latest glitch caused by supplier Spirit Aerosystems Holdings Inc. looks like it will be challenging to fix, he said.

“If anything it’s getting worse,” O’Leary said. “I would have been reasonably confident up until about a month ago that we would get 57 aircraft by the end of June. I’m now not confident.”

The added delay means Ryanair may receive as few as 40 737s by next summer, the CEO said. This will hurt flying capacity during the busy season and may mean Ryanair misses its target to transport 200 million passengers next year. The carrier already lowered its full-year traffic estimate for this year on the issue, to 183.5 million passengers from 185 million previously. 

Boeing is battling multiple issues on its mainstay narrowbody jet. The US planemaker and Europe’s Airbus SE have both struggled to ramp up production fast enough to meet soaring post-pandemic demand for new aircraft. 

Boeing delivered just 15 of its cash-cow Max jets last month — well short of targets — as it contended with time-consuming repairs of defects uncovered by Spirit. 

Asked if the issues would make the captive Boeing customer consider talking to Airbus, O’Leary said he considered it “on a daily basis” but that Airbus doesn’t have availability this side of 2030. 

Boeing said in a statement in response to Ryanair’s comments that “we value our partnership with Ryanair and are committed to supporting them.” 

Boeing shares slid as much as 2.3% on Thursday after Bloomberg reported on the additional Max delays. They were down 1.7% as of 11:59 a.m. in New York. Ryanair lost 1.8% in Dublin.

On Thursday, Ryanair rival EasyJet Plc said it would order 157 Airbus aircraft, with an option for another 100 on top, with deliveries stretching as far out as 2034. 

(Updates with US trading in ninth paragraph)

©2023 Bloomberg L.P.