American Airlines has updated some pilot training to include discussion about the automated system suspected of playing a role in the deadly 29 October crash of a Lion Air Boeing 737 Max, according to the company's pilots' union.
The training updates come amid expectation that Boeing is working on a software change to address concerns with the 737 Max's manoeuvring characteristics augmentation system (MCAS).
Boeing added MCAS to the 737 Max because that aircraft has slightly different flight characteristics from the earlier-generation 737NG. MCAS makes the 737 Max behave like the 737NG by trimming the stabiliser so that the aircraft's nose drops if the aircraft approaches stall with flaps up. Airlines say Boeing never informed them of the system.
MCAS is at the focus of the investigation into the Lion Air crash, which killed 189 people. The Lion Air pilots struggled for control as the aircraft's systems repeatedly pushed the nose down, possibly due to faulty angle-of-attack (AOA) indications. Lion Air's founder is now threatening to cancel his airline's remaining 737 Max orders.
Following the crash, the Federal Aviation Administration issued an emergency directive warning that faulty AOA data could trigger a dive, and requiring pilots be made aware of a "runaway stabiliser" checklist.
American is now providing pilots with updated ground school materials that include discussion of MCAS, the FAA's directive and circumstances that may have affected the Lion Air crew, says Dennis Tajer, communications committee chair for APA, which represents American's pilots.
Additionally, American's check airmen "got a really informative brief on MCAS" during American's quarterly meeting with check pilots, he says.
"It's being briefed from top to bottom, and all the information is flowing well," Tajer says.
Tajer says MCAS was also discussed during American's recent simulator training – though the airline has only 737NG simulators, which do not actually simulate the MCAS function.
The union is urging the airline to purchase 737 Max simulators.
"A simulator that would help us understand some of the flying characteristics better," Tajer says.
American did not respond to questions about training or simulators, but says it has been "working collaboratively" with the union since the Lion Air crash.
"We will continue to keep our pilots and maintenance professionals informed of any updates," American says.
Southwest Airlines has three 737 Max simulators on order, with the first expected to arrive in 2019, it says. The company does not say whether it implemented new training since the crash, but early this year Southwest implemented a new training programme aimed at helping pilots recover from aircraft upsets and unreliable cockpit readings.
Tajer says Boeing executives recently told union officials that the company is working with the FAA to issue an MCAS-related software update. Boeing told APA at the end of November that the upgrade would be finished within about eight weeks.
While not confirming software changes are underway, Boeing says it "continues to evaluate the need for software or other changes as we learn more from the ongoing investigation".
"As part of our standard practice following any accident or incident, we examine our aircraft design and operation, and when appropriate, issue bulletins and make recommendations to operators to further enhance safety," Boeing adds in a statement.
The Lion Air crash raised questions about the degree to which pilots need to understand increasingly-complex systems with which few will ever interact.
Some pilots fault Boeing for not divulging the presence of MCAS.
"This is not a… culture that is going to enhance safety," the APA's Tajer says. "Rationing and metering and choosing what not to disclose" is indicative of "diseased aviation".
But Boeing insists the existing "runaway stabiliser" checklist provides all steps needed to recover from a MCAS-induced stabiliser problem. That checklist instructs pilots to switch off stabiliser trim switches and, if needed, hold the stabiliser trim wheel.
But Tajer says that checklist excluded critical information. Specifically, American's runaway stabiliser checklist, written prior to the Lion Air crash, says uncommanded trim will be "interrupted when the control column is displaced in the opposite direction".
However, on 9 November, American Airlines' issued a 737 "fleet bulletin" saying that applying opposing force on the control column "will not stop" MCAS-directed downward pitch if MCAS is receiving incorrect AOA data.
"To us, that's proof that the runaway stabiliser checklist is not integrating this MCAS," Tajer says.