NTSB issues Boeing 737 MAX safety recommendations

The report has been issued as part of the NTSB’s ongoing support to Indonesia’s aviation investigators following the October 29, 2018, crash of Lion Air flight 610 in the Java Sea and their counterparts from Ethiopia following the crash of Ethiopian Airlines flight 302 near Ejere. All passengers and crew on board both aircraft – 346 people in all – died in the accidents. Both crashes involved a Boeing 737 MAX aircraft.

The seven safety recommendations issued to the FAA are derived from the NTSB’s examination of the safety assessments conducted as part of the original design of Boeing’s Maneuvering Characteristics Augmentation System (MCAS) on the 737 MAX and are issued out of the NTSB’s concern that the process needs improvement given its ongoing use in certifying current and future aircraft and system designs.

“We saw in these two accidents that the crews did not react in the ways Boeing and the FAA assumed they would,” said NTSB Chairman Robert Sumwalt. “Those assumptions were used in the design of the airplane and we have found a gap between the assumptions used to certify the MAX and the real-world experiences of these crews, where pilots were faced with multiple alarms and alerts at the same time. It is important to note that our safety recommendation report addresses that issue and does not analyse the actions of the pilots involved in the Lion Air and Ethiopian Airlines accidents. That analysis is part of the ongoing accident investigations by the respective authorities.”

The NTSB notes in the report that it is concerned that the accident pilots’ responses to unintended MCAS operation were not consistent with the underlying assumptions about pilot recognition and response that were used for flight control system functional hazard assessments as part of the Boeing 737 MAX design.

The NTSB’s report further notes that FAA guidance allows such assumptions to be made in certification analyses without providing clear direction about the consideration of multiple, flight-deck alerts and indications in evaluating pilot recognition and response. The NTSB’s report states that more robust tools and methods need to be used for validating assumptions about pilot response to airplane failures in safety assessments developed as part of the US design certification process.

The seven recommendations issued to the FAA urge action in three areas to improve flight safety:

  • Ensure system safety assessments for the 737 MAX (and other transport-category airplanes) that used certain assumptions about pilot response to uncommanded flight control inputs, consider the effect of alerts and indications on pilot response and address any gaps in design, procedures, and/or training.
  • Develop and incorporate the use of robust tools and methods for validating assumptions about pilot response to airplane failures as part of design certification.
  • Incorporate system diagnostic tools to improve the prioritization of and more clearly present failure indications to pilots to improve the timeliness and effectiveness of their response.

NTSB investigators continue to assist the ongoing investigations. The NTSB has full access to information from the flight recorders, consistent with standards and recommended practices for the NTSB’s participation in foreign investigations.

Aviation Safety Recommendation Report 19-01 is available online at https://go.usa.gov/xVv7P.