More details have emerged about the Ethiopian Airlines Boeing 737 Max 8 jet that crashed on March 10, killing all 157 people on board.
Investigators are still examining black box recordings, and while the exact cause of the crash is not yet known, they have found “clear similarities” to Lion Air Flight JT610, which crashed last October in the ocean off Indonesia shortly after take-off.
Last week the US Federal Aviation Authority (FAA) released satellite data showing that the flight track of the Ethiopian Airlines jet was similar to the Lion Air plane, prompting their choice to ground all 737 Max 8 jets in the US temporarily. The decision came days after the jets were grounded internationally by other regulatory bodies.
Implicated in the crashes is the Max’s automatic flight control system, called the Manoeuvring Characteristics Augmentation System (MCAS).
MCAS was introduced because the plane’s larger engines alter its lift and increase the likelihood of its nose pitching upwards in the air. It takes readings from two angle-of-attack sensors, which measure how air flows over the wings.
If the system detects that the plane is pointing too far upwards, suggesting a dangerously sharp ascent, MCAS automatically swivels the plane’s horizontal tail, which pushes the nose down to prevent a mid-air stall.
A report on the Lion Air crash suggested that a faulty angle-of-attack sensor repeatedly pitched the plane into a nose dive 26 times. The pilots struggled for 10 minutes, pulling its nose up each time before ultimately losing control.
A part recovered from the Ethiopian Airlines flight indicated the jet’s horizontal tail was in an unusual position, pointing to MCAS as a possible cause.
Lacking safety features?
Both planes lacked two optional safety upgrades that could have warned the pilots of problems contributing to the crashes, neither of which were mandated by the FAA, the New York Times reported on Thursday.
One of the optional safety features absent in both the Ethiopian Airlines and Lion Air jets was an angle-of-attack indicator, which displays the readings from the two sensors. The other was a warning light that switches on if the two readings differ, suggesting a sensor error.
Boeing will reportedly roll out the warning light as a standard safety feature as part of an update to MCAS software, but the angle-of-attack indicator will remain an optional upgrade.
In addition, the original safety analysis that Boeing delivered to the FAA on MCAS – a report used to certify the plane as safe to fly – had several crucial flaws, reported The Seattle Times on March 17.
It raises concerns about the regulatory body, which has in recent years delegated increasing responsibility to Boeing to certify the safety of its own planes.
Official reports about the cause of the Ethiopian Airlines crash will not be released for several months.
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