Boeing 737 MAX groundings

Boeing 737 MAX groundings
Boeing 737 MAX grounded aircraft near Boeing Field, April 2019.jpg
A parking lot at Boeing Field in Seattle, Washington, filled with undelivered Boeing 737 MAX aircraft
  • March 10, 2019 (UTC+3) (2019-03-10UTC+3) by Ethiopian Airlines
  • March 11, 2019 (2019-03-11) by CAAC (China)
  • March 12, 2019 (2019-03-12) by EASA
  • March 13, 2019 (2019-03-13) by FAA
DurationOngoing. 6 months and 7 days (since first grounding on March 10, 2019)
CausePrecautionary measure following two similar crashes less than five months apart

In March 2019, aviation regulators and airlines around the world grounded all Boeing 737 MAX passenger airliners after two MAX 8 aircraft crashed, killing the 346 people aboard. The accidents befell Lion Air Flight 610 on October 29, 2018 and Ethiopian Airlines Flight 302 on March 10, 2019. Ethiopian Airlines acted first, grounding its MAX fleet effective the day of the accident. On March 11, Chinese authorities ordered the first regulatory grounding, and most other agencies and airlines banned the airplane over the next two days. The Federal Aviation Administration (FAA) initially reaffirmed the airplane's airworthiness on March 11, but grounded it on March 13. The groundings affected 387 MAX aircraft delivered to 59 airlines.

In both accidents, pilots lost control to automated commands by the 737 MAX's new Maneuvering Characteristics Augmentation System (MCAS), which repeatedly pushed the airplane nose down in response to erroneous angle of attack (AoA) data. Pilots learned of the new "automatic trim" feature only after the first crash, when Boeing updated the airplane's flight manual and the FAA issued an emergency airworthiness directive. Boeing admitted that MCAS played a role in both accidents, and developed updates to the flight control systems, cockpit displays, and computer architecture, which took months longer than expected.

The U.S. Department of Transportation (DOT) and Congress launched investigations into FAA type certification of the MAX, particularly the FAA's delegation of authority to Boeing that allowed the company to conduct activities for certification on behalf of the agency. Technical safety experts from nine countries, the FAA, and NASA are jointly reviewing the certification of the MAX automated flight control system and its compliance with regulations. Industry experts said the panel's findings could change global standards for certification.

Boeing suspended deliveries and reduced production of the MAX, and might temporarily stop manufacturing the airplane if recertification is delayed beyond October 2019. Airlines canceled thousands of flights and leased other aircraft to fill in for the MAX. Boeing recorded a $4.9 billion charge for compensation to airlines and set up a separate fund to help families of accident victims. Pilots and families sued Boeing for allegedly concealing flaws in the airplane.


Lion Air Flight 610 crash

PK-LQP, the aircraft involved in the crash of Flight 610

On October 29, 2018, Indonesian Lion Air Flight 610 from Soekarno–Hatta International Airport in Jakarta to Depati Amir Airport in Pangkal Pinang crashed into the Java Sea 12 minutes after takeoff. All 189 passengers and crew were killed in the accident.[1][2][3] The preliminary report tentatively attributed the accident to the erroneous angle-of-attack data and automatic nose-down trim commanded by MCAS.[4][5] The 737 MAX aircraft was delivered 2 months and 16 days prior, on August 13, 2018. This is the deadliest crash involving the Boeing 737 regardless of variant.[6]

Boeing published a supplementary service bulletin addressing the AoA warning and the pitch system's potential for repeated activation, all without referring to MCAS by name. The bulletin describes warnings triggered by erroneous AoA data, and referred pilots to a "non-normal runaway trim" procedure as resolution, specifying a narrow window of a few seconds before the system's next application.[7] The FAA issued an Emergency airworthiness directive 2018-23-51, requiring the bulletin's inclusion in the flight manuals, and that pilots immediately review the new information provided.[8][9]

Ethiopian Airlines Flight 302 crash

ET-AVJ, the Ethiopian Airlines aircraft that crashed in Flight 302

On March 10, 2019, Ethiopian Airlines Flight 302 from Addis Ababa in Ethiopia to Jomo Kenyatta International Airport in Nairobi, Kenya, crashed six minutes after takeoff near Bishoftu, killing all 157 passengers and crew aboard the aircraft.[10][11][11][12][13] The 737 MAX was delivered 3 months and 23 days prior, on November 15, 2018, two weeks after the Lion Air accident.[14]

Initial reports indicated that the Flight 302 pilot struggled to control the airplane, in a manner similar to the circumstances of the Lion Air crash.[15] A stabilizer trim jackscrew found in the wreckage was set to put the aircraft into a dive.[16] Experts suggested this evidence further pointed to MCAS as at fault in the crash.[17][18] After the crash of flight ET302, Ethiopian Airlines spokesman Biniyam Demssie said in an interview that the procedures for disabling the MCAS were just previously incorporated into pilot training. "All the pilots flying the MAX received the training after the Indonesia crash," he said. "There was a directive by Boeing, so they took that training."[19] Ethiopia's transportation minister, Dagmawit Moges, said that initial data from the recovered flight data recorder of Ethiopian Flight 302 shows "clear similarities" with the crash of Lion Air Flight 610.[20][21]