American Airlines is set to cancel 90 flights per day by June 5, 2019, as its fleet of 24 Boeing 737 MAX is still grounded.

The Texas-based airline, that previously canceled some of its flights until the end of April 2019, said it would “contact affected customers directly by email or telephone” for rebooking.

American Airlines said it was currently awaiting information from the manufacturer and regulating authorities including the Federal Aviation Administration (FAA), Department of Transportation (DOT) and, National Transportation Safety Board (NTSB) to resume operations of the aircraft.

Earlier in the week, Southwest also admitted that the grounding of its 34 737 MAX planes has led to canceling about 150 flights per day, and would do so all the way until May 2019.

“The duration is one major factor of what makes this situation highly unusual — especially for our customers,” Chris Mainz, Southwest spokesman, told USA Today. “We know it’s been frustrating for our customers, but we have taken several steps to try to minimize the inconvenience and frustration”.

The two U.S. airlines are bracing for a long-term grounding, days after the FAA confirmed that the update of the Boeing 737 MAX would not be ready for “weeks”.

Boeing reduces production of 737 MAX

The entire 737 MAX fleet has been grounded for the past three weeks. Boeing announced on April 5, 2019, that it would reduce the production of the plane by about 20%, which means that the output should decrease from 52 aircraft per month to 42. Nonetheless, the manufacturer assured that “the 737 program and related production teams will maintain their current employment levels”.

Since it has paused deliveries of new planes, the company is stockpiling finished Boeing 737 MAXs in Renton factory.

As for the update of the aircraft software, the planemaker confirmed to The Wall Street Journal that a second flaw was discovered. However, Boeing said that this problem is unrelated to MCAS, and would be addressed as part of the software update.

Boeing told a committee was set to “confirm the effectiveness of our policies and processes for assuring the highest level of safety on the 737-MAX program, as well as our other airplane programs, and recommend improvements to our policies and procedures”.