What are the 737 Max jets? Why did two of them crash within five months of each other? And what is MCAS?
The crashes of Lion Air Flight 610 and Ethiopian Airlines Flight 302 have rocked the aviation industry, sparked numerous investigations, and resulted in the grounding of hundreds of Boeing 737 Max jets worldwide.
Lion Air Flight 610 took off from Jakarta, Indonesia on Monday, October 29th, 2018, at 6:20AM local time. Its destination was Pangkal Pinang, the largest city of Indonesia’s Bangka Belitung Islands. Twelve minutes after takeoff, the plane crashed into the Java Sea, killing all 189 passengers and crew.
Nearly five months later, Ethiopian Airlines Flight 302 took off from Addis Ababa, Ethiopia on Sunday, March 10th, 2019, at 8:38AM local time. Its destination was Nairobi, Kenya. Six minutes after takeoff, the plane crashed near the town of Bishoftu, Ethiopia, killing all 157 people aboard.
Both crashed jets were Boeing 737 Max 8s, a variant of the best-selling aircraft in history. When Airbus announced in 2010 it would make a new fuel-efficient and cost-effective plane, Boeing rushed to get out its own version. That version was the 737 Max airplanes. The Air Current has a great (if slightly insider-y) retelling of the Max jets’ origins.
What was the response?
The Indonesian rescue team located the flight data recorder on November 1st. The cockpit voice recorder was found over two months later, on January 14th, 2019. One member of the volunteer rescue team died during recovery operations. Both the cockpit voice recorder and the flight data recorder of Ethiopian Airlines 302 were recovered from the crash site on March 11th.
Both crashes are currently under investigation. These are the only two accidents involving the new Boeing 737 Max series of aircraft, which was first introduced in 2017. Since the crash of Ethiopian Airlines 302, more than 300 Boeing 737 Max passenger jets have been grounded worldwide.
But the US was slower to act than other countries. As China and the European Union announced their decision to ground the plane, the FAA declined to act. President Trump initially responded by tweeting on March 12th that airplanes had become too complex. “Pilots are no longer needed, but rather computer scientists from MIT,” Trump said in a series of tweets that didn’t specifically reference Boeing or the crashes. “Split second decisions are needed, and the complexity creates danger. All of this for great cost yet very little gain.”
Boeing CEO Dennis Muilenburg reportedly spoke to Trump that same day, urging him not to ground the Max 8. But on Wednesday, March 13th, Trump eventually bowed to pressure, directing the FAA to ground the plane. But the president also praised Boeing in the same breath, calling it “a great, great company with a track record that is so phenomenal.”
Boeing maintains that the new, more fuel efficient Max jets are safe, but supports the FAA’s decision to ground the planes. The Chicago-based company has stopped delivery of all new Max jets to its customers. Stock losses have wiped around $28 billion from its market value since the Ethiopian Airlines crash.
What caused these crashes?
Both crashes are currently under investigation, and there is no final word on what caused either tragedy. But investigators are focused on a specific tech feature that may have forced both planes into a nosedive seconds before the crashes.
A preliminary report from Indonesian investigators indicates that Lion Air 610 crashed because a faulty sensor erroneously reported that the airplane was stalling. The false report triggered an automated system known as the Maneuvering Characteristics Augmentation System, or MCAS. This system tried to point the aircraft’s nose down so that it could gain enough speed to fly safely.
MCAS takes readings from two sensors that determine how much the plane’s nose is pointing up or down relative to oncoming airflow. When MCAS detects that the plane is pointing up at a dangerous angle, it can automatically push down the nose of the plane in an effort to prevent the plane from stalling.
Investigators have found strong similarities in the angle of attack data from both flights. A piece of a stabilizer in the wreckage of the Ethiopian jet with the trim set in an unusual position was similar to that of the Lion Air plane, Reuters reports.
What is MCAS?
Boeing says the decision to include this change to the flight control operations wasn’t arbitrary. When the company designed the Max jets, it made the engines larger to increase fuel efficiency, and positioned them slightly forward and higher up on the plane’s wings.
These tweaks changed how the jet handled in certain situations. The relocated engines caused the jet’s nose to pitch skyward. To compensate, Boeing added a computerized system called MCAS to prevent the plane’s nose from getting too high and causing a stall. MCAS is unique to the Max jets, and isn’t present in other Boeing 737s. The Air Current has a great illustration of how MCAS works here. And The New York Times has a video that explains how MCAS is supposed to work.
MCAS is activated without the pilot’s input, which has led to some frustration among pilots of the 737 Max jet. At least half a dozen pilots have reported being caught off guard by sudden descents in the aircraft, according to the Dallas News. One pilot said it was “unconscionable that a manufacturer, the FAA, and the airlines would have pilots flying an airplane without adequately training, or even providing available resources and sufficient documentation to understand the highly complex systems that differentiate this aircraft from prior models,” according to an incident report filed with a NASA database.
Both jets that crashed lacked safety features that could have provided crucial information to the crew because they were sold as options by Boeing, according to The New York Times. This was previously reported by Jon Ostrower on The Air Current, who said that a warning light that would have alerted the crew to a disagreement between the Max jet’s angle of attack sensors wasn’t part of Lion Air’s optional package of equipment. According to the Times:
For Boeing and other aircraft manufacturers, the practice of charging to upgrade a standard plane can be lucrative. Top airlines around the world must pay handsomely to have the jets they order fitted with customized add-ons.
Sometimes these optional features involve aesthetics or comfort, like premium seating, fancy lighting or extra bathrooms. But other features involve communication, navigation or safety systems, and are more fundamental to the plane’s operations.
Boeing will stop charging extra for one of the safety features, a source tells the Times: the disagree light that was missing from both crashed jets, which would have activated if the angle of attack sensors were at odds with each other. That feature will now come standard in all new 737 Max planes.
Were pilots given adequate training?
Short answer: no. When the Max jet was under development, regulators determined that pilots could fly the planes without extensive retraining because they were essentially the same as previous generations, according to The New York Times. This saved Boeing a lot of money on extra training, which aided the company in its competition with Airbus to introduce newer, more fuel-efficient airplanes. The FAA didn’t change those rules after Lion Air 610 crashed.
So rather than hours-long training sessions in giant, multimillion-dollar simulators, many pilots instead learned about the 737’s new features on an iPad. Pilots at United Airlines put together a 13-page guide to the 737 Max, which did not mention the MCAS.
According to Reuters, the doomed Lion Air cockpit voice recorder revealed how pilots scoured a manual in a losing battle to figure out why they were hurtling down to sea.
Since the crash of Ethiopian Airlines 302, that’s mostly changed. On Sunday, March 17th, Muilenburg issued a statement describing steps the company was taking to update its technology. “While investigators continue to work to establish definitive conclusions, Boeing is finalizing its development of a previously-announced software update and pilot training revision that will address the MCAS flight control law’s behavior in response to erroneous sensor inputs,” Muilenburg said.
What about the FAA’s certification?
The approval process for Boeing’s Max jetliners was rushed and possibly compromised, according to a blockbuster report in The Seattle Times. Reporter Dominic Gates found that FAA managers pushed the agency’s engineers to delegate safety assessments to Boeing and to speedily approve the resulting analysis. Under pressure to approve its new Max jets so it could catch up to Airbus, Boeing turned in a safety assessment to the FAA that was riddled with errors, the Times reported.
Even the work that was retained, such as reviewing technical documents provided by Boeing, was sometimes curtailed.
The Department of Transportation’s inspector general is probing the FAA’s approval of the Max jets. The DOT’s investigation is focused on the FAA’s Seattle office, which certifies the safety of new aircraft. A subpoena seeking documents from the office, including emails, correspondence, and other messages has been issued, The Wall Street Journal reports.
The FBI is joining the mix of agencies investigating the crashes and their aftermath. According to The Seattle Times, the agency will lend its considerable resources to DOT agents probing the FAA’s certification of the Max jets.
What happens next?
The crash investigations are still ongoing. We have yet to hear any information from Ethiopian Airlines 302’s black box beyond initial (and vague) reports about similarities to Lion Air 610. More details should emerge soon.
The US Senate will convene a hearing on the FAA’s certification of Boeing 737 Max jets on March 27th, Reuters reports. Boeing executives and officials from the FAA will be called to testify at the first congressional hearing on the twin crashes. They will likely be asked why the regulator agreed to certify the Max planes in 2017 without requiring extensive additional pilot training.
On March 19th, Trump named Stephen Dickson, a former Delta Air Lines executive, as his choice to become the permanent head of the FAA. Dickson will no doubt face stiff questioning during his confirmation process, as more details about the agency’s certification of the Max jets trickle out.
Boeing and the FAA are currently at odds over how much pilot training will be required in conjunction with a coming software fix for MCAS, according to The Wall Street Journal. The FAA says it is keeping a close eye on Boeing’s software update that is intended to correct problems with MCAS, CNBC reports.
Indonesian officials held a briefing early on Thursday, at which they confirmed reports that an off-duty pilot was in the cockpit of the doomed Lion Air plane the day before the crash. According to Bloomberg, the plane experienced a similar malfunction that caused it to nosedive, but the off-duty pilot correctly diagnosed the problem and helped the crew disable the flight-control system and save the plane. The next day, the plane was under a completely different crew when it experienced the same problem, causing it to crash into the Java Sea.
Meanwhile, experts are questioning the legality of documents that the families of Lion Air 610’s victims say they are being pressured into signing, according to The New York Times. In order to collect payments of 1.3 billion rupiah, or $91,600, families are being required to sign a pledge promising not to pursue legal action against Lion Air, its financial backers, and Boeing. The pledge appears to violate Indonesian law.