United Airlines planned to operate up to 110 daily flights with the Boeing 737 Max by the end of year, more than double the number it flew when the type was grounded in March.

The Chicago-based carrier, which operated 14 737 Max 9s when the type was suspended, has warned of a growing impact from the grounding that, to date, it has mitigated by swapping in spare aircraft and postponing non-essential maintenance on others to cover its 50 daily Max flights at the time, a quarterly financial filing shows.

United 737 Max

United

But with the grounding expected to stretch into the summer, United has removed the 737-9 from schedules through July and warned of a greater impact to passengers to come.

"With 14 aircraft that was something that we could manage for a month or two, given some of the flexibility we have in our maintenance plans," said Greg Hart, chief operating officer of United, during a quarterly earnings call on 17 April. "But beyond that, it gets really tough to manage."

American Airlines and Southwest Airlines, the two largest 737 Max operators in the USA, have cancelled flights since the suspension. American has cancelled roughly 90 flights a day and Southwest up to 160 flights a day, both of which expect the grounding to continue through August.

United has yet to provide details on what flights could be impacted by the 737 Max suspension. However, it was operating the type on flights to Alaska, Hawaii and from its Houston hub previously.

The carrier has reduced its annual capacity growth forecast by a percentage point to up 4-5% in 2019 due to the 737 Max grounding and the temporary suspension of flights to Delhi.

United is scheduled to take delivery of another 16 737-9s in the second and third quarters, the filing shows.

Some of those deliveries are expected to slip into the fourth quarter, said United chief financial officer Gerry Laderman on the 17 April call.

Source: Cirium Dashboard