BOEING HAS SAID that it does not expect federal regulators to approve its changes to the grounded 737 Max until this summer, several months longer than the company was saying just a few weeks ago.

That timetable — the latest of several delays in the plane’s approval process — will create more headaches for airlines by pushing the Max’s return further into the peak summer travel season.

Even after federal officials approve changes Boeing is making to the plane, airlines will need more time to train pilots.

Boeing shares fell more than 5% by yesterday afternoon.

The company said regulators will decide when the Max flies again but that it periodically gives airlines and suppliers its best estimate of when that will happen.

“This updated estimate is informed by our experience to date with the certification process,” Boeing said in a statement.

“It is subject to our ongoing attempts to address known schedule risks and further developments that may arise in connection with the certification process. It also accounts for the rigorous scrutiny that regulatory authorities are rightly applying at every step of their review” of the plane’s flight controls and pilot-training requirements.

The latest timetable is based on work remaining to be done before the Federal Aviation Administration (FAA) will allow the Max back in the sky, according to two people familiar with the matter.

Shortly after the first Max crash in October 2018 in Indonesia, Boeing began updating software that investigators say was triggered by a faulty sensor and pushed the plane’s nose down.

Then in March 2019, another Max crashed in Ethiopia. In all, 346 people died.

Boeing has made the software less powerful and tied it to two sensors instead of one.

That work was done months ago, but the company is still working on changes to flight-control computers and pilot-training requirements.

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Another software issue was discovered last week, although one of the people familiar with the situation said it would not cause more delay in the plane’s return.

News of the latest delay in Boeing’s timing was first reported by CNBC.

The FAA said in a statement that it is conducting “a thorough, deliberate process” to make sure that Boeing’s changes to the Max meet certification standards.

The agency said, as it has for months, that it has no timetable for completing its review