![]() That's a sharper divergence than was seen in Lion Air Flight 610, where the two AoA sensors differed by about 20 degrees. The reading of the left angle of attack sensor increased sharply shortly after takeoff to 74.5 degrees and stayed there for the duration of the flight, compared to a 15 degree reading for the right AoA sensor. The plane maker is continuing to produce the 737 MAX and the older 737 NG at a rate of 52 a month, but it has halted deliveries of the MAX to customers.ĭetermining why the angle of attack sensor on ET302 malfunctioned will be a focus for investigators. Convincing regulators and airlines that it's safe to fly again is a crucial task for Boeing: It's the company's bestselling plane, with 4,600 on order. The 737 MAX has been grounded worldwide in the wake of the Ethiopian crash. It's our responsibility to eliminate this risk. As pilots have told us, erroneous activation of the MCAS function can add to what is already a high workload environment. This again is the case here, and we know we can break one of those chain links in these two accidents. In a statement, Boeing CEO Dennis Muilenburg said: “The history of our industry shows most accidents are caused by a chain of events. Says Goglia: "This would have been a challenge to any pilot except for maybe a Boeing test pilot."īoeing is working with FAA and other regulatory agencies worldwide to implement a software update to MCAS and additional pilot training procedures. “And Boeing didn’t help by not providing the proper information and designing a flawed system to begin with,” he says, referring to the plane maker’s decision that it wasn’t necessary to inform pilots that the MCAS system had been added to the new version of the 737. “They should have slowed the airplane down and then attempted to move the stabilizer.”īut Mackey says it's unfair to heap blame on the pilots, who were in an extremely stressful situation, with contradictory indicators: the control column shaking, an overspeed clacker sounding and altitude disagree and speed disagree warnings. “They’re trying to say their pilots did everything right, but they didn’t,” says Mackey. The only way those switches would have been functional is if the pilots had restored power to the automatic trim system, says Mackey. The report states that 30 seconds before the plane crashed, there were two attempts to bring the nose of the plane up using thumb switches on the pilots’ control columns. The report seems written in a way to obscure this, says Mackey. “In this scenario, each time you get more nose-down movement, do you get to the point where the force to trim manually is more than you can apply?” asks Mackey.Īfter failing to manually bring the nose back up, the pilots appear to have turned the motor to the rear stabilizers back on, which goes against the procedures recommended by Boeing and FAA, allowing the MCAS system to engage again. “This is a job for both pilots,” says Mackey.Īt high speed and with the stabilizers already at an extreme angle, it may have been difficult to impossible for the pilots to move the stabilizers by hand, Mackey says. That may indicate that only Mohamed tried to turn the trim wheel, says Mackey, but Mohamed alone may not have been able to exert the necessary force. At 05:41:54, the First-Officer replied that it is not working.” The First-Officer has replied that the trim was not working and asked if he could try it manually. ![]() The wording of the report also raises questions as to whether the pilots worked the trim wheels properly, Mackey says.Ībout three minutes after takeoff, the report states, “the Captain asked the First-Officer if the trim is functional. But takeoff power would still be excessive in the latter situation. "Either had so much going on he didn’t realize he had so much power, or if he thought he was stalling he was going to keep the power up, " Goglia says. The engines were set to 94% of maximum power on takeoff, and they remained at that setting throughout the flight, the report says, a highly unusual situation that investigators will need to examine, says John Goglia, an air safety consultant and former board member of the U.S. “The faster the airplane goes, the harder it is to move the stabilizer,” he says. Mackey questions why the pilots didn't ease up on the throttle. Airspeed indicators rose to over 340 knots, triggering overspeed warning alarms. However, based on the report, the pilots may have been unable to do so effectively, partly because the plane was flying extremely fast, putting heavy air pressure on the stabilizers, says Keith Mackey, a Florida-based air safety consultant and former airline pilot and crash investigator.
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