American Airlines Group Inc. pilots want the carrier to offer more training on Boeing Co.'s 737 Max to better understand new anti-stall software, after a preliminary report on an Indonesia plane crash suggested that aircraft malfunctions left aviators overwhelmed.

The Allied Pilots Association made the request after what the union said was an unprecedented meeting with Boeing officials this week. The manufacturer also met with Southwest Airlines Co.'s pilots union. Both carriers fly the Max, Boeing's latest iteration of the popular 737 jetliner. The new model replaced an older version called the next generation, or NG.

The APA is asking American "to consider additional days of training for these significant differences in the NG and the Max," said Dennis Tajer, a spokesman for the union and a 737 captain at the airline.

Boeing is working to bolster confidence in its systems after pilots from American and Southwest said they weren't informed about a flight-control system on the Max that can pitch the aircraft's nose downward if it suspects the plane is losing lift under its wings. That change was an early focus of the investigation into what caused the Lion Air jet to crash into the Java Sea last month, killing 189 people.

Safety Collaboration

The Chicago-based planemaker didn't immediately respond to a request for comment. American said its approach to safety is based on "open communication and collaboration with manufacturers, regulators and the unions." Southwest said it's working closely with its pilots union and Boeing. The United Continental Holdings Inc. chapter of another union, the Air Line Pilots Association, had no immediate comment about any meetings with Boeing. United also operates the Max.

American pilots flying the NG version of Boeing's single-aisle workhorse, the 737-700 and 737-800, took about an hour of online training on operating the Max. They also received training in a flight simulator for the older model on cross-wind landings because of the Max's larger engines and lower wing tips. American and Southwest don't have Max simulators.

"We were told that not much else is different," Tajer said in an interview Thursday. "Now we know there is. We'd like to revisit the training that pilots on the line have received now and going forward."

'Very Disconcerting'

Boeing reassured the Southwest Airlines Pilots Association that the company is "extremely confident there will be no more surprises" with the Max after a thorough review, Jon Weaks, president of the union and a captain at the airline, told members in a message. Southwest, which has an all-737 fleet, uses NG simulators to help train pilots for the Max, an airline spokesman has said.

The lack of disclosure about the anti-stall device known as the Maneuvering Characteristics Augmentation System "is still very disconcerting," Weaks said. "Boeing is proposing solutions and fixes for the MCAS system which should be in place before the end of the year."

A preliminary report released Wednesday by Indonesian regulators didn't give a cause of the accident, but suggested poor safety procedures and a struggle by the pilots to control a repeatedly malfunctioning airplane may have contributed to the crash.

Regulators detailed steps taken to address malfunctions reported on the plane the previous night and difficulties that aviators on both flights had figuring out basic information such as speed and altitude.

The pilots on the flight the night before the accident were able to disable the system pushing down the nose. They landed safely. In bulletins to airlines, Boeing has reminded carriers that a longstanding emergency procedure -- which pilots must memorize -- enables them to handle such malfunctions.