April 4 (Reuters) - The Ethiopian Civil Aviation Authority has released a preliminary report into an Ethiopian Airlines crash on March 10 that killed 157 people and resulted in the worldwide grounding of more than 300 Boeing 737 MAX jets.
The accident was the second fatal crash involving Boeing’s 737 MAX 8 model in five months, after a Lion Air flight crashed in Indonesia in October.
- The Ethiopian Airlines jet had faulty sensor readings indicating the “angle of attack”, which is the angle the plane must maintain to avoid going into a stall.
- Shortly after the autopilot was disengaged, the plane’s nose was pushed down automatically.
- The flight control problems meant the captain was unable to maintain the flight path and the crew lost control of the aircraft. The captain called “pull up” three times and the first officer acknowledged this.
- The airspeed and altitude values from the left air data system began deviating from the corresponding right side values.
- The crew followed all the recommended procedures to deal with the emergency, Ethiopian officials said when presenting the report. Safety experts said this would likely spark a debate over the conduct of the flight with U.S. regulators and Boeing.
- The captain asked the first officer if the trim was functional. The first officer replied that the trim was not working and tried it manually, but it still did not work.
- Two momentary electric trim inputs were made about 32 seconds before the end of the recording. Sources familiar with the aircraft say this suggests the system driving the MCAS anti-stall software had re-engaged, which only a person can do.
- The airspeed reached 500 knots (575 mph) just before the crash, according to one instrument. An alarm indicating excess speed was heard on the cockpit voice recorder.
- The report recommended that Boeing review flight control systems and that aviation authorities verify the problem has been resolved before the aircraft is allowed to fly again.
- The report’s purpose is to investigate, not assign blame liability.
Writing by Katharine Houreld; Editing by Kirsten Donovan