Plane manufacturer Boeing did not tell pilots or airlines that it had installed a new automatic system on the aircraft model that was involved in the crash of Lion Air Flight 610 in Indonesia last month.

The withheld information in question is that of a stall-prevention system that Boeing added to its new 737 MAX 8 and MAX 9 aircraft. The system is meant to stop pilots from angling the aircraft nose too high (which can affect the plane’s speed and lift and cause a stall) by automatically pushing the nose of the plane downward if it senses a stall is possible. But, as Boeing said in a memo after the crash, the system can suddenly push the nose so far down that pilots cannot lift it back up. The system would kick in even if cockpit crews are flying a plane manually and wouldn’t be anticipating a computerized system to take over.

Pilots and airlines did not know this system existed until a memo from Boeing went out over the weekend. Boeing did not include any mention of the system in the flight crew operations manual for the aircraft, which pilots read to familiarize themselves with a plane’s systems.

“Pilots are reacting with shock that they were cut out of the information loop,” aviation expert and author of “The Crash Detectives” Christine Negroni told TPG.

Driving the shock is the notion that a plane can institute a change without informing the pilot — and that the pilot would not know how to react. “Pilots train on the flight simulator for unexpected events, so you can react with a muscle memory,” Negroni says. “But if you don’t understand what’s happening that’s a problem.”

“It’s pretty asinine for them to put a system on an airplane and not tell the pilots who are operating the airplane, especially when it deals with flight controls,” Capt. Mike Michaelis, chairman of the safety committee for the Allied Pilots Association that represents 15,000 American Airlines pilots, told the Wall Street Journal. “Why weren’t they trained on it?”

Boeing’s 737 is a workhorse commercial jet for airlines across the world. The newest version of the narrowbody jet is the MAX generation. Quite a few airlines that have flown 737s in the past have opted to buy the MAX generation as part of an easy fleet upgrade because their pilots are already mostly accustomed to the flying the aircraft. “The big deal with marketing the MAX is you can go from 737 NextGen into the MAX without any kind of new [pilot] certification,” Negroni explains, noting that some airlines opt to do a video training for pilots flying the updated variant.

KARAWANG, INDONESIA - NOVEMBER 06: colleagues of victims of Lion Air flight JT 610 throw flowers on deck of Indonesian Navy ship KRI Banjarmasin during visit and pray at the site of the crash on November 6, 2018 in Karawang, Indonesia. Indonesian investigators said on Monday the airspeed indicator for Lion Air flight 610 malfunctioned during its last four flights, including the fatal flight on October 29, when the plane crashed into Java sea and killed all 189 people on board. The Boeing 737 plane crashed shortly after takeoff as investigators and agencies from around the world continue its week-long search for the main wreckage and cockpit voice recorder which might solve the mystery. (Photo by Ulet Ifansasti/Getty Images)
Photo by Ulet Ifansasti/Getty Images.

Investigators are now examining whether this automatic system contributed to the Lion Air plane’s crash, which killed all 189 people on board when it suddenly plunged into the Java Sea on Oct. 29. Indonesian officials had previously identified problems with downed plane’s airspeed indicator and another sensor that reports information on the angle of the nose. The Federal Aviation Administration has already acknowledge that errant data readings from those sensors could make “the aircraft difficult to control” and cause sudden and significant altitude loss and could lead to “possible impact with the terrain,” the regulatory body said in an emergency airworthiness directive last week. The FAA also instructed airlines with the MAX to add information about the anti-stall system into their aircraft manuals.

When asked about the system’s approval, an FAA spokesperson referred TPG to the original directive. “Based on initial information from the ongoing Lion Air accident investigation, the FAA issued an Emergency Airworthiness Directive (AD) ordering operators to revise the airplane flight manual (AFM) to give the flight crew horizontal stabilizer trim procedures to follow under certain conditions,” the spokesperson told TPG in an email. “The FAA will take further action if findings from the accident investigation warrant. We will not provide further comment on any aspect of the investigation while it remains open.”

In its new memo, Boeing told US airlines that operate the 737 MAX 8 — which include American Airlines with 16 MAX 8s and Southwest with 26 of the jet — that the automatic system was installed as part of the aircraft’s safety certification process with the FAA. The plane builder did not go into detail in the bulletin as to why the 737 MAX 8 (and the MAX 9) were the only variants of the popular 737 plane to have this system installed.

The American and Southwest pilots were told in the bulletin that the automatic system was added “to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall.”

But, Boeing said in the memo that the stall-prevention system is not mentioned to pilots in the aircraft flight manual because it didn’t think pilots would fly the plane in such a way that the automatic system would ever take over, explains Negroni, who has reviewed the memo with pilots who received it.

TPG reached out to Boeing for more information as to why the automatic system was installed if no pilot would ever fly the plane so that it kicked in. The plane builder’s statement did not address these inquiries, but it said that Boeing was “confident in the safety of the 737 MAX.”

“We are deeply saddened by the loss of Lion Air Flight JT 610,” Boeing’s emailed statement read. “We extend our heartfelt condolences and sympathies to the families and loved ones of those on board.  We are taking every measure to fully understand all aspects of this incident, working closely with the investigating team and all regulatory authorities involved,” the statement said, adding that “safety remains our top priority and is a core value for everyone at Boeing.”

JAKARTA, INDONESIA - OCTOBER 29: Wreckage from Lion Air flight JT 610 lies at the Tanjung Priok port on October 29, 2018 in Jakarta, Indonesia. Lion Air Flight JT 610 crashed shortly after take-off with no sign so far of survivors among the 189 people on board the plane. (Photo by Ed Wray/Getty Images)
Photo by Ed Wray/Getty Images.

Pilot unions for both Southwest and American have reportedly sent out memos informing their pilots that more information on the system would soon be added to the aircraft manual.

“This is the first description you, as 737 pilots, have seen,” American’s pilots’ union told its members in an alert. “It is not in the AA 737 Flight Manual Part 2, nor is there a description in the Boeing FCOM (flight crew operations manual),” the bulletin read, noting an addition would be made to the manual soon.

“We’re pissed that Boeing didn’t tell the companies and the pilots didn’t get notice obviously, as well,” president of Southwest Airlines’ pilot union Capt. Jon Weaks said to the Wall Street Journal. “But what we need now is… to make sure there is nothing else Boeing has not told the companies or the pilots.”

For now, both Southwest and American are continuing to operate their MAXs.

“Southwest’s MAX 8 fleet of 26 aircraft remains fully operational, and we do not expect any disruption to our schedule,” Southwest told TPG in a statement. “Safety is the top priority at Southwest, and we will continue to work closely with Boeing and the FAA to maintain the integrity of our fleet and validate our operating practices.” The airline added that it “issued additional communication highlighting the existing procedures to the more than 9,500 Southwest Pilots that operate our 737 MAX 8 fleet.”

American confirmed it was not informed of some of the behaviors of the anti-stall system, called a Maneuvering Characteristics Augmentation System (MCAS). “We value our partnership with Boeing, but were unaware of some of the functionality of the Maneuvering Characteristics Augmentation System (MCAS) installed on the MAX 8,” AA spokesperson Ross Feinstein told TPG in an email. “The work with the FAA and Boeing is on-going, and we will continue to keep pilots informed of any updates.”

American also said it has followed the regulations outlined by both the FAA and Boeing’s bulletins. “We complied with the Emergency Airworthiness Directive last Friday, which reiterates procedures already in the Quick Reference Handbook (QRH) for non-normal events. The Emergency Airworthiness Directive reiterated existing, well-established procedures for MAX 8 pilots. At American, we have not had similar issues regarding an erroneous Angle of Attack during manual flight.”

With aircraft becoming more and more computerized, Negroni says that pilots are largely told to trust the automated systems in an unknown situation. “The big thing is ‘trust your instruments, trust the airplane,’” she says. “And these pilots can’t.”

Featured image by BAY ISMOYO/AFP/Getty Images.

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