WASHINGTON -- U.S. regulators have told Boeing Co. that pilots may require additional training to properly respond to emergencies on the 737 Max after airline crews failed to perform proper procedures in simulator tests.
In a Feb. 19 letter to Boeing reviewed by Bloomberg News, the Federal Aviation Administration detailed multiple missteps that airline crews had made in the December simulator sessions and said additional tests are needed. The simulations replicated failures similar to those in two fatal crashes.
An analysis of the results by FAA and regulators in other nations reviewing revisions to the grounded jetliner may prompt "additional training requirements pertaining to the" aircraft, the letter said.
As a result of the tests, Boeing had already reversed its long-held position that Max pilots who were certified to fly on earlier versions of the 737 didn't need extra simulator training. But the letter provides more detail about issues raised in the sessions and is the first indication that the government is also examining the need for more training requirements.
It is the latest complication for Boeing's efforts to bring the 737 Max -- its best-selling jet -- back into service almost a year after it was grounded worldwide after the crashes. Decisions on training are important because they could delay the plane's return and be costly for airlines.
"We have submitted an initial recommendation regarding simulator training on the737 Max, but we will continue to work with airline customers and global regulators to assess and finalize the content of the training," Boeing said in an emailed statement. "Ultimately, it will be the regulators who determine the training requirements."
Pilots from the three U.S. carriers that fly the Max, American Airlines Group Inc., United Airlines Holdings Inc. and Southwest Airlines Co., along with a crew from Grupo Aeromexico SAB were tested in December simulations of multiple emergency scenarios.
The tests were conducted in a simulator running Boeing's updated flight-control system that was developed in the wake of the crashes. While none of the crews committed such egregious mistakes that they lost their planes, the errors were extensive, according to the FAA letter.
The pilots, who had received additional training proposed by the company, failed to finish emergency checklists related to the automated system involved in both 737 Max crashes, known as Maneuvering Characteristics Augmentation System.
In addition, they had difficulty with emergency procedures related to sensor failures, erroneous altitude and airspeed readings and the autopilot, among others, according to the letter.