From the New Yorker:
With virtually every day that has passed since the crash of Ethiopian Airlines Flight 302, which killed a hundred and fifty-seven people, more disturbing news has emerged. On Sunday, a spokesperson for Ethiopia’s ministry of transport said that the black box that was recovered from the wreckage of Flight 302 indicated that “clear similarities were noted between Ethiopian Airlines Flight 302 and Indonesian Lion Air Flight 610,” which crashed last October, killing a hundred and eighty-nine people…
Current and former engineers directly involved with the evaluations or familiar with the document shared details of Boeing’s “System Safety Analysis” of MCAS, which The Seattle Times confirmed.
The safety analysis:
- Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.
- Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.
- Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed.