By Tracy Rucinski
CHICAGO (Reuters) - The U.S. Federal Aviation Administration plans to test next month how pilots with around one year of experience flying Boeing 737 jets handle new software on the MAX model, four sources with knowledge of the matter said.
The tests indicate the FAA is making progress in the re-approval process of the MAX for commercial flight. Boeing Co's (N:BA) latest 737 narrowbody model, the MAX, was grounded worldwide in March following two fatal crashes in Indonesia and Ethiopia that killed 346 people within five months.
Since then, airlines that rushed to buy the MAX to service new and longer routes with the jet's fuel-efficient engines have had to cancel thousands of flights as they manage slimmer fleets, eating into their profitability.
Boeing, the world's largest planemaker, has said it is working towards getting the 737 MAX flying again commercially in the early fourth quarter, once the FAA approves new pilot training and reprogrammed software for a stall-prevention system at the centre of both crashes.
As part of its own testing process Boeing has invited senior U.S. airline pilots to experiment with the software fix and use simulators to run scenarios similar to the ones that led to the two crashes. But the FAA wants to observe relatively inexperienced 737 pilots, the sources said on condition of anonymity because the tests are confidential.
To do so, the FAA asked Southwest Airlines (N:LUV), American Airlines (O:AAL) and United Airlines (O:UAL) - the three U.S. carriers that operate the MAX - to provide the names of newer 737 line pilots who have flown the MAX at least once, they said.
The exact nature of the tests, which they said is likely a first step towards creating a wider test group, was still being decided but could include a scenario discovered by the FAA in June that showed a microprocessor flaw causing an uncommanded movement of the plane's horizontal tail which took test crew too long to recognise as a loss of control known as runaway stabilizer.
One source said the test was supposed to be conducted during the first week of September but has been pushed back to the middle of the month.
Boeing declined to comment while the FAA did not immediately comment.
The Chicago-based planemaker started delivering the MAX, its fastest-selling aircraft, in 2017 before more than 50 airlines worldwide were forced to park some 380 jets.
Since April Boeing has been running rigorous rounds of test flights with the new software, both in flight simulators and in the air, as it looks to improve the safety of its best-selling aircraft, with about 5,000 pending orders.
Southwest, the largest MAX operator with 34 jets, has removed the aircraft from its flight scheduling until early 2020, while American and United have scheduled without the MAX until early November, leading to hundreds of daily flight cancellations.
The longer the grounding lasts, the harsher the impact on airlines that have been awaiting new MAX deliveries.
Separately, sources told Reuters that Boeing plans to resume production of 737 jets at a rate of 52 aircraft per month in February 2020. It reduced the number of 737s it produces monthly to 42 from 52 when MAX deliveries were frozen in April, cutting off a key source of cash and hitting margins.