JetBlue Airways Corp. has yet to start New York-London service and already has been forced to trim the schedule as travel restrictions hobble demand.

“We’ve all been very frustrated the corridor hasn’t opened,” Chief Executive Robin Hayes said Tuesday. “There’s no reason not to open it. It’s not data driven.”

The carrier will fly its once-daily route between New York’s John F. Kennedy International Airport and London’s Heathrow starting Aug. 11 but will “bring down some of the flying” in September, he said on a quarterly earnings call.

The airline will adjust the schedule monthly after that to match demand, Hayes said. JetBlue didn’t elaborate on plans for flights from New York to London’s Gatwick Airport, which are set to begin Sept. 29.

The Covid-19 pandemic has hammered the normally highly competitive trans-Atlantic market since the New York-based carrier revealed plans in 2019 to join the fray. JetBlue has vowed to undercut “obscene” business-class fares on the route to woo travelers and has touted a remodeled premium-class cabin as well as added leg room in coach.

Hayes’s comments Tuesday came as the airline failed to join some rivals by forecasting profits for the third and fourth quarters.

“Naturally, this leaves us wondering whether JetBlue simply exhausted its pricing salvo prematurely, selling too much too soon too cheaply, and thereby not enjoying the summer yield momentum experienced by others,” Jamie Baker, an analyst at JPMorgan Chase & Co., said in a note to clients.

JetBlue tumbled 7.3% to $14.90 at 2:56 p.m. in New York after sliding as much as 8%, the largest intraday decline since March. The airline will report pretax profits in July and August, Hayes said.

The U.S. Centers for Disease Control and Prevention last week advised Americans against traveling to the U.K., after cases of the coronavirus delta variant climbed there. The Biden Administration has kept travel restrictions in place for the U.K. and 26 other European countries.

Americans who have been fully vaccinated in the U.S. still must quarantine for 10 days on arrival in Britain. Heathrow’s chief executive has said he expects the country to announce that it will open up to vaccinated Americans by the end of the month.