Recorders Show 'Similarities' between 737 Max Crashes

 - March 18, 2019, 9:15 AM
All Boeing 737 Max 8s remain grounded until further notice from global aviation authorities. (Photo: Boeing)

Information gleaned from the flight data and cockpit voice recorders recovered from the Ethiopian Airlines Boeing 737 Max 8 that crashed just southeast of Addis Ababa on March 10 shows “clear similarities” between that disaster and the October 29 crash of a Lion Air Max 8 off the coast of Indonesia, Ethiopian transport minister Dagmawit Moges reported during a Sunday press conference in the Ethiopian capital. The French air accident investigation agency BEA over the weekend successfully completed downloading the recordings of the CVR and FDR from the ill-fated Ethiopian jet in Paris and handed over the data to Ethiopian investigators. Moges did not elaborate on the nature of the similarities, but she said investigators managed to recover virtually all of the data inside the devices. Moges added that the Ethiopian investigation team and the investigators from the U.S. National Transportation Safety Board confirmed the accuracy of the data copied.

Officials believe the FDR and CVR data will provide vital clues into the cause of the March 10 crash, in which all 157 passengers and crewmembers died. Although not all civil aviation authorities acted in harmony, all of the more than 375 Max 8s delivered throughout the world now sit grounded. The U.S. Federal Aviation Administration on March 13 became the last major authority to order the suspension of Max operations following investigators’ examination of space-based ADS-B data recovered from Aireon that also suggested similarities between the Ethiopian crash and the Lion Air accident. All 189 people aboard the Indonesian-registered jet died in that crash.

Moges said officials would release detailed information on the Ethiopian crash within a month.

Meanwhile, Boeing continues to develop a product update designed to mitigate the possibility of an uncommanded dive originating from false readings from the airplane’s angle-of-attack sensor. The design changes include activation and angle-of-attack signal “enhancements” and a maximum command limit of the maneuvering characteristics augmentation system (MCAS).

Meant to improve pitch response at high angles of attack and prevent pilots from raising the airplane’s nose too high, the MCAS in the 737 Max 8 and Max 9 does not appear in the 737 NG. Engineers made the change to address differing stall characteristics in the Max resulting from its larger and heavier CFM Leap-1B engines. The MCAS can, however, force the airplane into a dive under circumstances such as faulty inputs from its angle-of-attack sensor, potentially leading to a crash, according to a November 7 emergency airworthiness directive issued by the FAA.

“Safety is our highest priority as we design, build, and support our airplanes,” said Boeing CEO Dennis Muilenburg in the company’s most recent written statement on the progress of the software update. “As part of our standard practice following any accident, we examine our aircraft design and operation, and when appropriate, institute product updates to further improve safety...We also continue to provide technical assistance at the request of and under the direction of the National Transportation Safety Board, the U.S. Accredited Representative working with Ethiopian investigators.”