A key sensor had been wrecked, possibly by a bird strike. As soon as they retracted the landing gear, flaps and slats, it began to feed faulty data into the Maneuvering Characteristics Augmentation System (MCAS), designed to prevent stalls.
Flying faster than recommended, the crew struggled with MCAS. But the high speed made it nearly impossible to use the controls to pull the nose up.
Moments later, the Boeing Co jet hit the ground, killing all 157 people onboard after six minutes of flight.
Ethiopian authorities said on Thursday that the pilots followed all the correct procedures in trying to keep MCAS from sending the plane into a fatal dive.
But the full picture of what happened in the cockpit of Flight 302 on March 10 is emerging from a preliminary report and a newly released data plot showing how crew and technology interacted.
The airline’s youngest-ever captain, a 29-year-old with an impressive 8,100 hours flying time, and his rookie 25-year-old co-pilot may have made a crucial mistake by leaving the engines at full take-off power, according to data and other pilots.
By the end, the aircraft was traveling at 500 knots (575 mph, 926 kph), far beyond its design limits.
That and some other potential missteps may have left them unable to fight flawed Boeing software that eventually sent the jet into an uncontrollable dive, experts said after studying the data.
“Power being left in take-off power while leveling off at that speed is not a normal procedure,” said one U.S. pilot, who declined to be named because he was not authorized to speak to the media. “I can’t imagine a scenario where you’d need to do that.”
The Ethiopian Airlines crash, and another in Indonesia five months earlier, have left the world’s largest planemaker in crisis as its top-selling jetliner is grounded worldwide, and Ethiopia scrambling to protect one of Africa’s most successful companies.
Boeing is working on a software fix for MCAS and extra pilot training, which its chief executive, Dennis Muilenburg, said would prevent similar events from happening again. [NAN]