FAA Lifts Boeing 737 Max Grounding Order
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Two Boeing 737 Max 8s crashed, killing 346 people.
Boeing
Twenty months after it grounded the [/tags/boeing/ Boeing] 737 Max over a pair of crashes in 2018 and 2019 that killed 346 people, the Federal Aviation Administration [/news/boeing-737-max-gets-faa-clearance-to-resume-flights/ has cleared the beleaguered aircraft] to return to return to the sky. As part of the decision the agency has ordered Boeing and airlines to make repairs to a flight control system [/news/investigators-report-on-737-max-crash-blames-boeing-design-lion-air-staff/ blamed for both crashes] and increase pilot training.
The Max can't actually carry passengers until those steps are completed, and other reports have identified other potential problems with the airliner's [/news/faa-737-max-needs-additional-computer-changes/ flight control computer], [ wiring and engines]. Airlines operating the Max, however, are pushing ahead with plans to add the Max back into their fleets by the end of the year.
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For now the FAA's order affects only the US. Aviation safety agencies in [ Canada], [ Brazil] and the [/news/european-union-begins-737-max-certification-flights/ European Union] are conducting their own reviews of the plane. Until those are completed, the 737 Max will remain grounded in some places.
The developments have been a huge blow to Boeing, which has thousands of 737 Max orders on its books. Even once it's flying again worldwide, the company will have to work vigorously to retain the trust of airlines and the flying public for the Max family. Here's everything else we know about the airliner so far.
What happened in the two crashes?
In the first crash, on Oct. 29, 2018, [ Lion Air flight 610] dove into the Java Sea 13 minutes after takeoff from Jakarta, Indonesia, killing 189 people. The flight crew made a distress call shortly before losing control. That aircraft was almost brand-new, having arrived at Lion Air three months earlier.
The second crash occurred on March 10, 2019 when Ethiopian Airlines flight 302 departed Addis Ababa Bole International Airport bound for Nairobi, Kenya. Just after takeoff, the pilot radioed a distress call and was given immediate clearance to return and land. But before the crew could make it back, [ the aircraft crashed] 40 miles from the airport, six minutes after it left the runway. Aboard were 149 passengers and eight crew members. The aircraft involved was only four months old.
The 737 Max 9, shown here at the 2016 Paris Air Show, is a larger version of the Max 8, but with the same piloting system that's under investigation.
Kent German/CNE[ no longer flew the plane][ no longer flew the plane] by the time of the first crash.) [ Seating between] 162 and 210 passengers, depending on the configuration, it's designed for short- and medium-haul routes, but also has the range (3,550 nautical miles, or about 4,085 miles) to fly [ transatlantic] and between the [ mainland US and Hawaii]. The larger [ ] first flew in 2017, and the Max 10 has yet to fly ([ it made its formal debut Nov. 22], 2019). The smaller 737 Max 7 [ ] in May 2018.
A 737 history
[/news/boeing-737-much-more-than-just-the-max/ Boeing 737: Much more than just the Max]
The design of the 737 Max series is based on the Boeing 737, an aircraft series that [/news/boeing-737-much-more-than-just-the-max/ has been in service since 1968]. As a whole, the 737 family is the best-selling airliner in history. At any given time, thousands of some version of it are airborne around the world and some airlines, like Southwest and Ryanair, have all-737 fleets. If you've flown even occasionally, you've most likely flown on a 737.
What's different about the 737 Max series compared with earlier 737s?
The 737 Max can fly farther and carry more people than the [/news/boeing-737-much-more-than-just-the-max/ previous generation of 737s], like the 737-800 and 737-900. It also has improved aerodynamics and a [ redesigned cabin interior] and flies on bigger, more powerful and more efficient CFM LEAP engines. CFM is [ ] between [ ] and France's Safran.
Those engines, though, required Boeing to make critical design changes. Because they're bigger, and because the 737 sits so low to the ground (a deliberate 737 design choice to let it serve small airports with limited ground equipment), Boeing moved the engines slightly forward and raised them higher under the wing. (If you place an engine too close to the ground, it can suck in debris while the plane is taxiing.) That change allowed Boeing to accommodate the engines without completely redesigning the 737 fuselage -- a fuselage that hasn't changed much in 50 years.
But the new position of the engines changed how the aircraft handled in the air, creating the potential for the nose to pitch up during flight. A pitched nose is a problem in flight -- raise it too high and an aircraft can stall. To keep the nose in trim, Boeing designed software called the Maneuvering Characteristics Augmentation System, or MCAS. When a sensor on the fuselage detects that the nose is too high, MCAS automatically pushes the nose down. (For background on MCAS, read these excellent in-depth stories from [ The Air Current] and [ The Seattle Times].)
Compared with previous versions of the 737, the Max's engines sit farther forward and tour đi thái lan higher up on the underwing pylons.
Andrew Hoyle/CNET
What caused the crashes?
Planes crashed rarely have a single factor, which is the case here. On Oct. 25, 2019, the Indonesian National Transportation Safety Committee [/news/investigators-report-on-737-max-crash-blames-boeing-design-lion-air-staff/ published its final report] on the Lion Air crash. The report identifies nine factors that contributed to the crash, but largely blames MCAS. Before crashing, the Lion Air pilots were unable to determine their true airspeed and altitude and they struggled to take control of the plane as [ it oscillated] for about 10 minutes. Each time they pulled up from a dive, MCAS pushed the nose down again.
"The MCAS function was not a fail-safe design and did not include redundancy," the report said. Investigators also found that MCAS relied on only one sensor, which had a fault, and flight crews hadn't been adequately trained to use the system. Improper maintenance procedures, confusion in the cockpit and the lack of a cockpit warning light (see next question) contributed to the crash, as well.
More on the Lion Air accident report
[/news/investigators-report-on-737-max-crash-blames-boeing-design-lion-air-staff/ Report on 737 Max 8 crash blames Boeing design, Lion Air staff]
On March 9, 2020, almost one year to the day since the crash in Addis Ababa, Ethiopia's Aircraft Accident Investigation Bureau [ published an interim analysis]. Like the Indonesian findings, it cites design flaws with MCAS such its reliance on a single [ angle-of-attack sensor]. It also blamed Boeing for providing inadequate training to crew on using the Max's unique systems. (The Seattle Times [ has a great deep dive] on the report.)
Unlike their Indonesian counterparts, the Ethiopian investigators do not mention maintenance problems with the plane nor does it blame the flight crew. "The aircraft has a valid certificate of airworthiness and maintained in accordance with applicable regulations and procedures," the report said. "There were no known technical problems before departure."
Until [ Ethiopia releases another report], remember that crash investigations are tremendously complex -- it takes months to evaluate the evidence and determine a probable cause. Investigators must examine the debris, study the [/news/airbus-a350-a380-paris-air-show/ flight recorders] and, if possible, check the victims' bodies to determine the cause of death. They also involve multiple parties including the airline, the airplane and engine manufacturers, and aviation regulatory agencies.
When was the Max grounded?
About 30 airlines operated the Max by the time of the second crash (the three largest customers being Southwest Airlines, American Airlines and Air Canada). Most of them [ quickly grounded] their planes a few days later. Besides the airlines already mentioned that list includes United Airlines, WestJet, Aeromexico, Aerolíneas Argentinas, GOL Linhas Aéreas, Turkish Airlines, FlyDubai, Air China, Copa Airlines, Norwegian, Hainan Airlines, Fiji Airways and Royal Air Maroc.
More than 40 countries have also banned the 737 Max from flying in their airspace. China (a huge Boeing customer and [/features/chinas-aviation-future-rests-with-the-comac-c919-aircraft/ a fast-growing commercial aviation market]) led the way and was joined by Indonesia, Thailand, Malaysia, Australia, tour thái lan India, Oman, the European Union and Singapore. Canada initially hesitated, but soon [ reversed course].
Up until March 13, 2019, the FAA also declined to issue a grounding order, saying in a statement [ tweeted the previous day] that there was "no basis to order grounding the aircraft." That was despite a public outcry from [ ] and [ two flight attendant unions]. But following President Trump's [/news/trump-all-boeing-737-max-8-planes-are-grounded-immediately/ decision to ground] the Max that day, the agency cited [ new evidence] it had collected and analyzed.
Older [ 737 models], like the 737-700, 737-800 and 737-900, don't use MCAS and aren't affected.
Of the four 737 Max versions, only the Max 10 has yet to fly.
Boeing
What was the problem with the warning light?
[ The Air Current] reported March 12, 2019 that the Lion Air plane lacked a warning light designed to alert pilots to the faulty sensor and that Boeing sold the light as part of an optional package of equipment. When asked about the warning light, a Boeing spokesman gave CNET the following statement:
"All Boeing airplanes are certified and delivered to the highest levels of safety consistent with industry standards. Airplanes are delivered with a baseline configuration, which includes a standard set of flight deck displays and alerts, crew procedures and training materials that meet industry safety norms and most customer requirements. Customers may choose additional options, such as alerts and indications, to customize their airplanes to support their individual operations or requirements."
But on April 29, 2019, [ The Wall Street Journal] said that even for airlines that had ordered it, the warning light wasn't operating on some Max planes that had been delivered (a fact the Indonesian accident report confirmed). Then on June 7, 2019, Reps. Peter DeFazio, a Democrat from Oregon, and Rick Larsen, a Democrat from Washington, said [/news/boeing-wanted-to-delay-fix-on-737-max-warning-light-say-lawmakers/ they'd obtained information] suggesting that even though the plane maker knew the safety alert wasn't working, it decided to wait until 2020 to implement a fix.
Boeing responded to DeFazio and Larsen in a statement sent to CNET the same day.
"The absence of the AOA Disagree alert did not adversely impact airplane safety or operation," the statement read. "Based on the safety review, the update was scheduled for the MAX 10 rollout in 2020. We fell short in the implementation of the AoA Disagree alert and are taking steps to address these issues so they do not occur again."
The original version of the 737 first flew in 1967.
Boeing
What kind of MCAS training did 737 Max pilots receive?
Not much, which was a factor cited in both crash reports. As the Indonesian report said, "The absence of guidance on MCAS or more detailed use of trim in the flight manuals and in flight crew training, made it more difficult for flight crews to properly respond."
Though MCAS was new to the Max, existing 737 pilots didn't have to train on a simulator before they could start flying the Max. Instead, they learned about the differences it brought through [ an hour's worth of iPad-based training]. MCAS received scant mention. The reason? It was because Boeing, [ backed by the FAA], wanted to [ minimize the cost and time] of certifying pilots who'd already been trained on other 737 versions. To do so, Boeing and the FAA treated the Max as just another 737 version, rather than a completely new airplane (which it pretty much is).
Pilot [/news/pilots-confronted-boeing-about-737-max-before-second-crash/ complaints about the lack of training] emerged quickly after the Lion Air crash. On Nov. 12, 2018, [ The Seattle Times reported] that Max pilots from Southwest Airlines were "kept in the dark" about MCAS. [ The Dallas Morning News found] similar complaints from American Airlines pilots four months later.
The previous model, the 737-900ER, doesn't have the MCAS flight control system.
Boeing/Ed Turner
Are there any other issues with the aircraft besides MCAS?
There are a few.
In December, 2019, the FAA said [ it was looking at a potential problem] with two bundles of wiring that power control surfaces on the aircraft's horizontal stabilizer. Because the bundles are close together, there's a remote possibility that they could short-circuit and (if not noticed by the flight crew) send the plane into a dive. Boeing, however, is arguing [ a fix isn't necessary], since earlier 737s have the same wiring design, and has proposed [ leaving the bundles as they are].The same month, the FAA said [ it was investigating software] that verify whether key systems on the aircraft are functioning correctly.Then in February, Boeing [ notified the FAA of a malfunction with an indicator light] for the stabilizer trim system, which raises and lowers the Max's nose. The indicator, which notifies pilots of a malfunction, was turning on when it wasn't supposed to. Boeing also is investigating whether [ it needs to better insulate the engine cowlings] from lightning strikes in flight. Separately, CFM International said there [ may be a potential weakness] with a rotor on the Max's engines.In April, the FAA instructed Boeing [/news/faa-737-max-needs-additional-computer-changes/ to make two additional [
the company issued a safety warning][ the company issued a safety warning] advising 737 Max operators to deactivate MCAS if a flight crew encountered conditions like the Lion Air pilots experienced. It also [ expressed sympathy] for victims' families and [/news/boeing-pledges-100m-to-families-of-those-killed-in-737-max-8-crashes/ pledged $100 million] in support, and [ it quickly backed] the US grounding order.
"There is no greater priority for our company and our industry," Boeing said in a March 13, tour thái lan giá rẻ 2019 statement. "We are doing everything we can to understand the cause of the accidents in partnership with the investigators, deploy safety enhancements and help ensure this does not happen again."
As is common after a crash, [ Boeing didn't comment] on preliminary findings of either investigation, but the day after the Ethiopian crash the company [ said it would] issue a software update that would include changes to MCAS, pilot displays, operation manuals and crew training.
Following the Lion Air accident report, then CEO Dennis Muilenburg said the company was "addressing" its safety recommendations. "We commend Indonesia's KNKT for its extensive efforts to determine the facts of this accident, the contributing factors to its cause and recommendations aimed toward our common goal that this never happens again," he said.
The grounding order also caused Boeing to [ halt production] of the Max [/news/boeing-resumes-737-max-production/ for four months] in January, 2020.
Did Boeing know about Max problems before the crashes?
There is evidence that it did. On Oct. 17, 2019, Boeing revealed [ it revealed text messages] between two of the company's top pilots sent in 2016, which indicated the company knew about problems with the MCAS system early on. In one of the messages, a former chief technical pilot for the Boeing 737 described the MCAS' habit of engaging itself as "egregious."
Later that month, [ as he appeared before] two congressional committees, Muilenburg admitted Boeing [ knew of the test pilot concerns] in early 2019. "I was involved in the document collection process, but I relied on my team to get the documents to the appropriate authorities," he said. "I didn't get the details of the conversation until recently."
Then on Jan. 10, 2020 Boeing [ released a series of explosive emails] and instant messages to Congress in which Boeing employees discussed the 737 Max. Though [ some expressed regret for the company's actions] in getting the aircraft certified -- "I still haven't been forgiven by God for the covering up I did last year," one employee wrote in 2018 -- others openly discussed the 737 Max's flaws [ and joked about the FAA's approval process]. "This airplane is designed by clowns who in turn are supervised by monkeys," another employee wrote. (The New York Times [ has compiled the documents online].)
Did Boeing change its leadership?
Yes, but it didn't happen quickly. Though Muilenburg [/news/boeing-ceo-says-he-wouldnt-hesitate-to-put-his-family-on-a-737-max/ apologized] to the victims' families in an interview with [ CBS News] in May, 2019, he came under sharp criticism for his response to the crashes. On Oct. 11, 2019, Boeing announced it had [ taken away his role as chair] so that as CEO, Muilenburg could "focus full time on running the company as it works to return the 737 Max safely to service."
Muilenburg spent the next two months [ resisting calls] for his resignation from his other position, but on Dec. 23, 2019 the company announced that he had stepped down. "The Board of Directors decided a change in leadership was necessary to restore confidence in the company moving forward as it works to repair relationships with regulators, customers, and all other stakeholders," Boeing [ said in a statement]. Chairman David Calhoun [/news/new-boeing-ceo-takes-over-as-737-max-problems-remain-unresolved/ officially replaced] Muilenburg on Jan. 13, 2020.
Calhoun had defended Muilenburg before taking the top role, but in a March 5, 2020 interview [ with the New York Times] he said his predecessor had needlessly rushed production of the Max before the company was ready. "I'll never be able to judge what motivated Dennis, whether it was a stock price that was going to continue to go up and up, or whether it was just beating the other guy to the next rate increase."
Separately, on Oct. 22, 2019, the company [/news/boeing-ousts-exec-as-it-announces-significant-progress-on-737-max-fixes/ said it replaced] Boeing Commercial Airplanes CEO Kevin McAllister, the official overseeing the 737 Max investigation, with Stan Deal, former president and CEO of Boeing Global Services.
