The crash of the Ethiopian Airlines 737 MAX 8 on Sunday, which resulted in 157 fatalities, has prompted regulators around the world to ground the Boeing jet. The FAA issued a grounding order on Wednesday, which stated that based on the wreckage and satellite-based tracking of the jet’s route, it detected parallels between last weekend’s crash and that of the Lion Air 737 MAX 8, which went down in Indonesia in October and caused 189 fatalities.
According to the FAA, the similarity between both crashes will “warrant further investigation of the possibility of a shared cause for the two incidents that need to be better understood and addressed.”
Boeing and the FAA were already implementing procedures to deal with the presumed causes of the Lion Air crash, yet last weekend’s events altered their plans.
Though Indonesia has yet to publish any findings regarding the cause of the Lion Air crash, the agency had reviewed the MAX’s Maneuver Characteristics Augmentation System (MCAS). Boeing had designed the system after it discovered during testing that the placement of the 737 MAX engine, which is higher and farther out on the wing than on previous models, pitched the aircraft upward in certain conditions, which could result in the plane stalling.
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157 people have died after Ethiopian Airlines flight ET 302 crashed six minutes after leaving Addis Ababa for Nairobi. Seven Britons were among passengers from 35 different nations. The pilot is believed to have reported difficulties and had asked to turn back, before air traffic control lost signal with the aircraft. The Boeing 737-8 MAX was just a few months old and is the same type as the Lion Air plane which crashed into the sea off Indonesia last year killing all 189 on board. #ethiopianairlines #planecrash #et302 #kenya #nairobi #addisababa #ethiopia
When the MCAS senses that the plane is climbing too sharply without sufficient speed, it pushes the yoke forward and utilizes the horizontal stabilizer on the tail to pull the nose of the plane down. “It’s a fancy name for what we used to call ‘a stick pusher,’” says Ross Aimer, CEO of Aero Consulting Experts. The system is different than autopilot, and only goes into effect when the plane is being flown manually.
On the Lion Air flight, the MCAS activated unnecessarily. The 737 MAX was ascending normally, but as a result of a faulty sensor, the digital flight data recorder identified a 20-degree difference in the angle of attack between the left and right sides. The pilots then tried for ten minutes to pull the plane’s nose back up, but the MCAS kept pushing the yoke forward, thrusting the plane downward until it crashed into the Java Sea.
The pilots were unaware the MCAS was faulty and may have even been oblivious to the fact that the MCAS existed since Boeing did not mention it in the jet manual. In November, the company claimed that they were concerned about “inundating average pilots with too much information—and significantly more technical data—than they needed or could digest.” Meanwhile, the company was selling the 737 MAX as being mechanically similar to the previous 737, stating that pilots would hardly need new training.
After the Lion Air crash, the FAA issued an Emergency Airworthiness Directive, telling Boeing to update its manual and provide instructions regarding the MACS. “If an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands,” it said.
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Britain's aviation authority is banning Boeing’s best-selling 737 MAX planes from UK airspace, joining a growing list of countries and airlines that have suspended operation of the jets after a second deadly crash in less than six months. Investigators were still trying to determine the cause of Sunday's Ethiopia Airlines crash, which killed all 157 people on board. Similarities between that crash and another deadly crash in October in Indonesia, both of which involved 737 MAX 8s, has sparked intense scrutiny on the Boeing plane. Boeing says it has "full confidence in the safety" of it 737 MAX jets and it is not issuing any new guidance. The US Federal Aviation Administration decided not to ground the Boeing 737 MAX 8. (📸: Pall Jokull for Icelandair/The Brooklyn Brothers via Getty Images)
“We have this strange failure of this sensor signal, and behind it unfortunately we have a weak system implementation,” said Bjorn Fehrm, a Swedish Air Force veteran and aviation analyst with Leeham News and Analysis in regard to the Lion Air crash.
Boeing had begun warning airlines that the MAX’s angle of attack sensors had failed before and that malfunction could result in the MCAS pushing the aircraft’s nose down. It advised pilots to resolve the problem by cutting off the trim system and operating the plane manually. The company was also in the process of updating the MACS software to prevent it from activating after one sensor reading as well as limiting how many times it could engage.
Boeing said the update would take a few months. Their plan has been upended after the Ethiopian Airlines accident. Though it is unclear if the plane’s MCAS caused the aircraft to crash, what is certain is the 737 MAX will remain grounded until Boeing resolves the issue.