Adds shares, detail on grounded planes and analyst comment in paragraphs 1, 4 and 9, Airbus delivery schedule paragraphs 11-12

By Joanna Plucinska and Chandini Monnappa

June 5 (Reuters) - Budget carrier Wizz Air WIZZ.L reported an around 62% slide in annual operating profit on Thursday, citing capacity constraints due to grounded planes, sending its shares down 24%.

European airlines have warned of longstanding delivery delays and uncertainty around maintaining post-COVID demand amid the economic turmoil tied to U.S. President Donald Trump's tariff threats. However, the sector has largely benefited from lower fuel prices.

Wizz Air in particular has been affected by repair problems with RTX RTX.N-owned Pratt and Whitney engines, limiting its ability to increase capacity. It has issued two profit warnings in the past year.

Chief Executive Jozsef Varadi blamed grounded planes for the carrier's challenges. Wizz Air had 37 aircraft grounded as of May 9. By the end of the first half of its 2026 financial year, it expects 34 aircraft to remain grounded, with a repair shop visit for repaired engines expected at around 300 days.

"We have the benefit of more than a year of experience operating under these unique circumstances – conditions airlines would never experience when demand exceeds supply," he said in a statement.

Wizz Air reported 167.5 million euros ($191 million) in operating profit for the financial year ended March 31, down 61.7% from a year ago and missing the 246 million euros projected by analysts polled by LSEG.

In January, Varadi said that he expected the airline to be impacted by the engine repair issues for another two to three years.

Wizz Air shares have dropped 48% year-on-year, continuing the carrier's streak as the worst stock performer among European airlines.

Analysts pointed to potential higher costs tied to retiring Wizz's A320ceo fleet projected for next year and airport cost improvements for dampening recovery hopes.

The company said it would not provide guidance for 2026 at this stage of the year, citing limited visibility across its trading seasons.

However, it noted that its delivery schedule from Airbus AIR.PA had also been revised down.

"Given lease returns, the fleet is now forecast to grow from 231 aircraft as at the end of March 2025 to 305 aircraft as at end March 2028; this compares to the previous forecast of 380 aircraft at that end date," it said in the statement.

($1 = 0.8767 euros)

(Reporting by Joanna Plucinska in London and Chandini Monnappa in Bangalore; Editing by Mrigank Dhaniwala, Aidan Lewis and Emelia Sithole-Matarise)

((Joanna.Plucinska@thomsonreuters.com; 00447721669853; Reuters Messaging: @joannaplucinska))