Feb. 14 (UPI) -- United Airlines announced Friday it's extending its grounding of Boeing 737 Max aircraft until Labor Day weekend.
The airline said it won't fly the beleaguered aircraft again until Sept. 4.
"During this period, we'll continue to take extraordinary steps to protect our customers' travel plans," a statement from the airline said. "Moving forward, we'll continue to monitor the regulatory process and nimbly make the necessary adjustments to our operation and our schedule to benefit our customers who are traveling with us."
United previously had plans to resume flying the Boeing 737 Max in June.
President Donald Trump ordered the Federal Aviation Administration to ground all Boeing 737 Max 8 aircraft after two crashes involving the model killed nearly 350 people. An Ethiopian Airlines crash on March 10 killed 157 people and a Lion Air crash Oct. 29 in Indonesia killed 189. United doesn't have any Max 8 aircraft, but it owns more than a dozen Max 9s, which were also grounded.
United said it will ground between 56 and 108 flights daily from February through early September, with a monthly high of 3,300 flights in May.
The company said it's working to automatically rebook customers who've already purchased tickets on affected flights.
Investigators determined the crashes in 2018 and 2019 were due to flaws in the planes' automated flight software, which Boeing has been ordered to fix.