New York (CNN Business) United Airlines now plans to cancel all flights involving Boeing 737 Max planes until August — a month longer than previously announced.

The airline expects to cancel roughly 2,400 flights in June and July, a large chunk of the busy summer travel season.

"We won't put our customers and employees on that plane until regulators make their own independent assessment that it is safe to do so," United said in a statement. The company added that it will continue trying to automatically rebook affected customers on other flights.

United said in April that it would cancel all flights through " early July " because of the Boeing 737 Max grounding. The latest extension is through August 3.

The airline joins other US carriers — American and Southwest — that have canceled 737 Max flights until sometime in August. Boeing's Max planes were taken out of the skies in March after a 737 Max jet flown by Ethiopian Airlines pilots crashed in that country, killing everyone aboard. It was the second fatal crash involving a Max in recent months. A total of 346 people died in the two crashes.

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