The pilots of Ethiopian Airlines flight 302, which crashed with the loss of 157 passengers and crew, did everything right as they battled to save the aircraft, the carrier has said.
The airline said that the preliminary report clearly showed that the pilots “followed the Boeing recommended and FAA approved emergency procedures to handle the most difficult emergency situation created on the airplane”.
In a statement ahead of the release of the accident investigators’ interim findings, Ethiopian Airlines said: “Despite their hard work and full compliance with the emergency procedures, it was very unfortunate that they could not recover the airplane from the persistence of nose diving.”
The plane plunged into the ground shortly after take-off from Addis Ababa airport on 10 March.
The evidence from the interim report into the Ethiopian Airlines tragedy points firmly to a malfunction involving the Maneuvering Characteristics Augmentation System (MCAS).
The Max variant of the popular 737 aircraft has its engines mounted higher and further forward on the wing, which affects the balance and aerodynamic properties.
The design increases the possibility of a high-speed stall, and so MCAS software was installed on all Boeing 737 Max aircraft to counteract the risk.
The software monitors the “angle of attack” between the airflow and the wing. If it becomes too steep, an elevator in the tail automatically lifts to nudge the nose of the plane down, restoring the aircraft to an appropriate trim.
But this safety system was devised to respond to a single measure of the angle of attack – even though the sensor that provided the reading could be faulty.
It is believed that the sensor was damaged during take-off by either a bird strike or a foreign object on the runway.
This provided an inaccurate reading that triggered the MCAS, forcing the nose down.
The pilots followed the correct procedure to attempt to override MCAS, but appear to have been unsuccessful in correcting the nose-down attitude.
Boeing has developed new software that aims to address the concerns about MCAS and is awaiting approval from the FAA before installing it on the 371 grounded aircraft.
The FAA has been heavily criticised for insisting that the aircraft was safe despite many aviation authorities, including the CAA, grounding the jet. Two days after the crash, the FAA’s acting administrator Daniel Elwell, said: “Thus far, our review shows no systemic performance issues and provides no basis to order grounding the aircraft.”
The following day, the FAA grounded the Boeing 737 Max.
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