American Airlines pilots have revealed they expect to conduct simulator tests of a software fix for the Boeing 737 MAX this weekend as Garuda Indonesia moved to cancel its order for the single-aisle plane.
Reuters quoted Allied Pilots’ Association safety committee chairman Mike Michaelis as saying a union pilot and a management pilot would test the new software in simulators in Renton, Washington, the home of the 737.
READ: why are the investigators withholding vital clues into 737 MAX crashes?
“This airplane can be a safe airplane, and there have been great strides on getting a fix in the works, but I’ll have a better feel after we can test it out,” Michaelis told the news agency.
American has 24 737 MAX 8 aircraft, the second biggest fleet in the US, and said last week it had confidence in the planes after operating almost 18,000 flights.
The global fleet of 737 MAX jets has been grounded after two fatal crashes, one involving Indonesian carrier Lion Air in October and another Ethiopian Airlines on March 10.
READ: Lion Air investigators confirm the presence of third pilot.
The US Federal Aviation Administration, which is facing investigations into how the plane was certified, has labeled review of the new software an “agency priority”.
Boeing began working on changing pilots displays, operations manuals and crew training relating to new software on the 737 MAX after the crash in Indonesia last October of a Lion Air plane with 189 passengers and crew.
The pilots were still fighting the aircraft as it plunged into the ocean off Jakarta after the software, known as the Maneuvering Characteristics Augmentation System (MCAS), repeatedly pushed down its nose because of incorrect information from a single angle of attack sensor.
However, they failed to follow an established procedure that would have allowed them to shut off the system by flicking two switches.
MCAS is now being updated to allow access to more than one angle of attack sensor input, limit the number of stabilizer trim commands when the software receives an erroneous AoA reading and provide a limit to the stabilizer command to allow pilots to retain elevator authority.
Boeing is also understood to be making standard on the MAX a system that tells pilots when the two angle of attack sensors are not giving the same reading. That system had previously been an option.
Aviation Week & Aerospace Technology’s Guy Norris revealed this week that Boeing had already completed a flight test of the enhanced software to validate the updates to MCAS and improved pilot displays.
The test on a Boeing 737 MAX 7 prototype evaluated the system under multiple high angle-of-attack scenarios, Norris reported.
He said the enhanced software was demonstrated to the FAA on March 12 and the 80-minute test flight simulated stalls and other maneuvers meant to test the revised automatic stabilizer-trim input at altitudes between 13,500ft and 17,350ft.
Boeing has said the software will be released no later than April but it may take longer for the affected planes to return to service.
Meanwhile, both Reuters and AFP reported that Garuda has sent a letter to Boeing asking if it could cancel its 737 MAX order and switch to other Boeing models.
“We have sent a letter to Boeing requesting that the order be canceled,” Garuda spokesman Ikhsan Rosan told AFP.
“The reason is that Garuda passengers in Indonesia have lost trust and no longer have the confidence (in the plane).
Garuda is still awaiting a response from Boeing and there were suggestions the airline had already been having second thoughts about the order.
It has already received one 737 MAX as part of a 50-plane order worth $US4.9 billion at list prices, although airlines never pay the list price.
Lion Air has also had delayed deliveries of the MAX.
