Boeing has acknowledged it had to correct flaws in its 737 MAX flight simulator software used to train pilots, after two deadly crashes involving the aircraft that killed 346 people within six months.
The US-based aerospace company said its simulators were incapable of replicating certain flight conditions that contributed to the Ethiopian Airlines crash in March, or the Lion Air accident off Indonesia last October.
“Boeing has made corrections to the 737 MAX simulator software and has provided additional information to device operators to ensure that the simulator experience is representative across different flight conditions,” Boeing said in a statement on Saturday.
The company did not indicate when it first became aware of the problem, and whether it informed regulators.
Its statement marked the first time Boeing admitted there was a design flaw in software linked to the 737 MAX, whose MCAS anti-stall software has been blamed in large part for the Ethiopian Airlines tragedy.
The 737 MAX was grounded around the world in March following the Ethiopian Airlines crash that killed all 157 on board just five months after a similar crash of a Lion Air flight of a 737 MAX killed 189 people.
The company said the latest “changes will improve the simulation of force loads on the manual trim wheel,” a rarely used manual wheel to control the plane’s angle.
“Boeing is working closely with the device manufacturers and regulators on these changes and improvements, and to ensure that customer training is not disrupted,” it added.
Southwest Airlines, a major 737 MAX customer with 34 of the aircraft in its fleet, told AFP news agency it expected to receive the first simulator “late this year”.
American Airlines, which has 24 of the aircraft, said it had ordered a 737 MAX simulator that will be delivered and put into operation in December.
“As a result of the continuing investigation into both aircraft accidents, we are looking at the potential for additional training opportunities in coordination with the FAA (Federal Aviation Administration) and Allied Pilots Association,” it added.
On Thursday, Boeing said it had completed a software update for its 737 MAX jets and that is also submitting a plan on pilot training to the US Federal Aviation Administration.
The planes are awaiting approval from US and international regulators before they can return to service.
Currently, there is only one flight simulator specific to the 737 MAX in the United States, and it is owned by Boeing, according to FAA documentation.
US airlines train their pilots flying the MAX on a simulator built for the 737 NG, the version preceding the 737 MAX in the 737 aircraft family.
Oliver McGee, a former US deputy assistant secretary for transportation, said it’s vital for pilots to have access to accurate training systems.
“These simulators are very important to the airline operators,” he told Al Jazeera from Lubbock, Texas. “It can cost about tens of millions of dollars over the life of the aircraft.”
“American Airlines is already on board, saying we’re going to get those simulators and get more data and information, to the manufacturers, from the pilots where the manoeuvrability and controllability of the MCAS takes place,” he added.
US airlines have targeted August as the date they expect to resume flying on the 737 MAX.