FILE - A Boeing 737 MAX 8 airplane being built for India-based Jet Airways, takes off on a test flight at Boeing Field in Seattle,  April 10, 2019. A global team of experts next week will begin reviewing how the Boeing 737 Max's flight control system...
FILE - A Boeing 737 MAX 8 airplane being built for India-based Jet Airways, takes off on a test flight at Boeing Field in Seattle, April 10, 2019. A global team of experts next week will begin reviewing how the Boeing 737 Max's flight control system...

The Federal Aviation Administration expects to approve Boeing Co.'s 
737 MAX jet to return to service as soon as late June, representatives of the U.S. air regulator informed members of the U.N. aviation agency in a private briefing Thursday, sources told Reuters. 

The target, if achieved, means U.S. airlines would most likely not have to greatly extend costly cancellations of 737 MAX jets they have already put in place for the peak summer flying season, but the FAA representatives warned that there was no firm timetable to get the planes back in the air. 

American Airlines Group Inc., Southwest Airlines Co. and United Airlines suspended 737 MAX flights into July and August after the FAA grounded Boeing's best-selling jet in March following two crashes in the space of five months that together killed 346 people. 

FAA and Boeing officials privately briefed members of the International Civil Aviation Organization's (ICAO) governing council in Montreal on the 737 MAX on Thursday, the same day that the FAA's acting administrator. Dan Elwell. met with international air regulators for eight hours in Fort Worth, Texas.

Laying out a potential schedule for getting the 737 MAX back in the air in the United States goes further than the FAA's public statements so far. 

Elwell declined to answer questions about the private ICAO briefing.

"The last thing I want is to put a date out there and then to have anybody, either the FAA or you or the public, drive to the date instead of the end result of the process," he told Reuters at a briefing with reporters after the Fort Worth meeting, which he called "constructive." 

Safety first

He repeated previous statements that the FAA will not approve the plane for flight until it has completed a safety analysis, with no set timetable. 

The path to getting the 737 MAX back in the air outside the United States remains even more uncertain. Canada and Europe said on Wednesday that they would bring back the grounded aircraft on their own terms, not the FAA's. 

Shares of Boeing, the world's largest plane maker, pared earlier losses on Thursday to close down 0.6% at $350.55. The stock has fallen about 17 percent since the second crash, of an Ethiopian Airlines jet in March, wiping about $40 billion off its market value. 

Daniel Elwell, acting administrator of the Federal
Daniel Elwell, acting administrator of the Federal Aviation Administration, testifies during a House Transportation Committee hearing on Capitol Hill in Washington, May 15, 2019, on the status of the Boeing 737 MAX aircraft.

Software fix 

The FAA has said it will not reverse its decision to ground the plane until it sees the findings of a multiagency review of Boeing's plan to fix software on the 737 MAX, which the plane maker has described as a common link in the two crashes. 

Boeing said last week it had completed an update to the software, known as MCAS, which would stop erroneous data from triggering an anti-stall system that automatically turned down the noses of the two planes that crashed, despite pilot efforts to prevent such action.

Boeing has yet to formally submit the fix to the FAA and has not set a date to do so. 

"Once we have addressed the information requests from the FAA, we will be ready to schedule a certification test flight and submit final certification documentation," Boeing communications director Chaz Bickers said on Thursday. 

Even after the FAA lifts its ban on 737 MAX flights, airlines will have to spend about 100 to 150 hours getting each aircraft ready to fly again after being put in storage, plus time for training pilots on the new software, officials from the three U.S. airlines that operate the 737 MAX told Reuters. 

Southwest, American and United provided estimates to Reuters after discussing the process with Boeing in Miami earlier this week. 

Southwest is the world's largest MAX operator with 34 jets, followed in the United States by American  with 24 and United with 14. All three have dozens more on order, meant to service booming air travel demand. 

Long checklist

Each airline has a long list of items to tick off as it uploads the new 737 MAX software, including fluid changes and engine checks. 

FAA associate administrator Ali Bahrami said on Thursday it could take up to a week to return the planes to service following approval, noting that some grounded 737 MAX planes have missed scheduled inspections during the grounding. 

On top of that, each airline must train its pilots on the new software.

Boeing has said that simulator training is not necessary for the 737 MAX, and is recommending a mandatory computer-based course that explains MCAS and could be completed at a pilot's home in about an hour, according to pilot unions. 

Elwell said on Thursday that "no individual country stood up and said we need to have sim [simulator] training."

The FAA has made no decision yet on what type of pilot training will be required. Each airline will be responsible for developing its own training plan once the FAA lays down guidelines. 

If the FAA hits its target of approving the 737 MAX to fly by the end of June, airlines may still have to adjust their schedules for the busy summer travel season. 

United has removed the MAX from its flight schedule through July 3, Southwest through Aug. 5 and American through Aug. 19. 

For Southwest and American, that has meant more than 100 daily flight cancellations during the summer travel season. Both have said they will start using the aircraft as spares if they are ready to fly before those dates.