Archive for the ‘MCAS’ Category

Ethiopian Air pilots turned off 737 MAX anti-stall system. Then it turned on again

April 3rd, 2019
Parts of an engine and landing gear lie in a pile after being gathered by workers during the continuing recovery efforts at the crash site of Ethiopian Airlines flight ET302 on March 11, 2019 in Bishoftu, Ethiopia. (Photo by Jemal Countess/Getty Images)

Enlarge / Parts of an engine and landing gear lie in a pile after being gathered by workers during the continuing recovery efforts at the crash site of Ethiopian Airlines flight ET302 on March 11, 2019 in Bishoftu, Ethiopia. (Photo by Jemal Countess/Getty Images) (credit: Getty Images)

The pilots of Ethiopia Airlines Flight 302 apparently followed the proper steps to shut down an errant flight control system as they struggled to regain control of the 737 MAX aircraft shortly after takeoff. But according to multiple reports, data from the ill-fated aircraft’s flight recorder revealed that the anti-stall feature of the aircraft’s Maneuvering Characteristics Augmentation System (MCAS) was triggered at least three times—and at least one time after the pilots followed the correct steps to shut it down.

Both Reuters and The Wall Street Journal report that the air crew followed procedures laid out by Boeing following the crash of a Lion Air 737 MAX in October, according to officials briefed on the initial findings of the investigation. But the pilots failed to regain control of the system, and the MCAS was reactivated again—triggering yet another automated correction of the aircraft’s stabilizers that would have pushed the nose of the plane down.

Boeing’s safety notice following the Lion Air crash noted that the MCAS’ automated adjustments to a 737 MAX’s stabilizers—the control surfaces on the tail of the aircraft that are used to change the direction of the aircraft’s flight—could be “stopped and reversed” with a thumb switch on the pilot’s yoke but “may restart 5 seconds after the [switch] is released.”

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Posted in Biz & IT, Boeing 737 MAX, Ethiopian Airlines Flight 302, Federal Aviation Administration, Lion Air Flight 610, MCAS | Comments (0)

Boeing delays 737 MAX software fix delivery

April 2nd, 2019
The 737 MAX cockpit's layout is nearly identical to this 737-800's.  The software behind the glass isn't.

Enlarge / The 737 MAX cockpit's layout is nearly identical to this 737-800's. The software behind the glass isn't. (credit: Cory W. Watts)

Delivery of Boeing’s promised fix to the flight system software at the center of two 737 MAX crash investigations has been pushed back several weeks after an internal review by engineers not connected to the aircraft raised additional safety questions. The results of the “non-advocate” review have not been revealed, but the Federal Aviation Administration confirmed on April 1 that the software needed additional work.

“The FAA expects to receive Boeing’s final package of its software enhancement over the coming weeks for FAA approval,” an FAA spokesperson said in a statement. “Time is needed for additional work by Boeing as the result of an ongoing review of the 737 MAX Flight Control System to ensure that Boeing has identified and appropriately addressed all pertinent issues.”

The Maneuvering Characteristics Augmentation System (MCAS) was developed by Boeing to mitigate changes in the handling of the 737 MAX from other 737 designs. It included a more aggressive anti-stall feature intended to counter the modified aircraft’s inherent tendency to “nose up” during flight—automatically correcting the position of the aircraft’s stabilizers to bring the nose back down. Evidence from the crashes of a Lion Air 737 MAX off Indonesia in October and an Ethiopian Airlines flight last month indicates that a single faulty sensor input caused the anti-stall system to activate in error, pushing both aircraft into a dive shortly after take-off. Lack of diagnostic information and a change in how pilots would normally disable the software also contributed to the Lion Air crash; the investigation of the Ethiopian Airlines crash is still in progress.

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Posted in Biz & IT, Boeing 737 MAX, Ethiopian Airlines Flight 302, Lion Air Flight 610, MCAS | Comments (0)

Initial findings put Boeing’s software at center of Ethiopian 737 crash

March 29th, 2019
The Boeing 737 MAX's MCAS software was officially linked by FAA investigators to the crash of an Ethiopian Airlines flight earlier this month. The software was intended to compansate for the aerodynamic differences caused by the aircraft's larger engines.

Enlarge / The Boeing 737 MAX's MCAS software was officially linked by FAA investigators to the crash of an Ethiopian Airlines flight earlier this month. The software was intended to compansate for the aerodynamic differences caused by the aircraft's larger engines.

At a high-level briefing at the Federal Aviation Administration on March 28, officials revealed "black box" data from Ethiopian Airlines Flight 302 indicated that the Boeing 737 MAX's flight software had activated an anti-stall feature that pushed the nose of the plane down just moments after take-off. The preliminary finding officially links Boeing's Maneuvering Characteristics Augmentation System (MCAS) to a second crash within a five month period. The finding was based on data provided to FAA officials by Ethiopian investigators.

MCAS was partly blamed for the crash of a Lion Air 737 MAX off Indonesia last October. The software, intended to adjust the aircraft's handling because of aerodynamic changes caused by the 737 MAX's larger turbofan engines and their proximity to the wing, was designed to take input from one of two angle of attack (AOA) sensors on the aircraft's nose to determine if the aircraft was in danger of stalling. Faulty sensor data caused the MCAS systems on both the Lion Air and Ethiopian Airlines flights to react as if the aircraft was entering a stall and to push the nose of the aircraft down to gain airspeed.

On March 27, acting FAA Administrator Daniel Ewell told the Senate Commerce, Science, and Transportation Committee's aviation subcommittee that there had been no flight tests of the 737 MAX prior to its certification to determine how pilots would react in the event of an MCAS malfunction. He said that a panel of pilots had reviewed the software in a simulator and determined no additional training was required for 737-rated pilots to fly the 737 MAX.

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Posted in Biz & IT, Boeing, Boeing 737 MAX, Ethiopian Airlines Flight 302, FAA, Federal Aviation Administration, fly-by-wire, Lion Air Flight 610, MCAS, Policy | Comments (0)

Safety feature that could have prevented 737 MAX crashes sold by Boeing as an option

March 21st, 2019
Boeing passenger jet shortly after takeoff.

Enlarge (credit: Marian Lockhart / Boeing)

The crashed Lion Air 737 MAX and the Ethiopian Airlines 737 MAX aircraft had more in common than aircraft design and the apparently malfunctioning flight system that led to their demises. Both of the planes lacked optional safety features that would have alerted the pilots to problems with their angle of attack (AOA) sensors—the input suspected of causing the Maneuvering Characteristics Augmentation System (MCAS) software to put both aircraft into a fatal dive.

The New York Times reports that both vehicles lacked an "AOA disagree" light—a warning light that indicates when the aircraft's two AOA sensors provide different readings—and an angle of attack indicator. Since the MCAS system relied only on one of the aircraft's AOA sensors, the disagree light and AOA indicator would have given the flight crew visible evidence of a sensor failure and prompted them to disable the MCAS. But both of these features were sold by Boeing as expensive add-ons. And many discount and smaller airlines declined to purchase them, as they were not required by regulators.

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Posted in air safety, Biz & IT, Boeing 737 MAX, Ethiopian Airlines Flight 302, flight control systems, Lion Air Flight 610, MCAS | Comments (0)

US to ground all Boeing 737 MAX 8 and 9 jets in wake of crash [Updated]

March 13th, 2019
A Lion Air Boeing 737 MAX 8 crashed in October 2018; a software fix based on the investigation was delayed by the US government shutdown. It's possible that the fix could have prevented the crash of a similar aircraft in Ethiopia on March 10, 2019.

Enlarge / A Lion Air Boeing 737 MAX 8 crashed in October 2018; a software fix based on the investigation was delayed by the US government shutdown. It's possible that the fix could have prevented the crash of a similar aircraft in Ethiopia on March 10, 2019. (credit: PK-REN, Jakarta, Indonesia )

Update: President Donald Trump announced Wednesday afternoon that the Federal Aviation Administration will order all 737 MAX 8 and 737 MAX 9 planes be grounded.

"We’re going to be issuing an emergency order of prohibition to ground all flights of the 737 Max 8 and the 737 Max 9 and planes associated with that line," Trump said. "Pilots have been notified, airlines have been all notified. Airlines are agreeing with this. The safety of the American people and all people is our paramount concern."

Original story: Despite two crashes within six months, a growing number of grounding orders worldwide for the Boeing 737 MAX, and a number of recent complaints from US pilots over problems with the aircraft's automatic trim controls, the Federal Aviation Administration continues to allow the 737 MAX to fly. "The United States Federal Aviation Administration is not mandating any further action at this time, and based on the information currently available, we do not have any basis to issue new guidance to operators," a Boeing spokesperson said in a March 12 statement.

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