The
New York Times has posted this update on the crash:
Black Box Data Reveals Pilots’ Struggle to Regain Control of Doomed JetNov. 27, 2018
Data from the jetliner that crashed into the Java Sea last month shows the pilots fought to save the plane almost from the moment it took off, as the Boeing 737’s nose was repeatedly forced down, apparently by an automatic system receiving incorrect sensor readings.
The information from the flight data recorder, contained in a preliminary report prepared by Indonesian crash investigators and scheduled to be released Wednesday, documents a fatal tug-of-war between man and machine, with the plane’s nose forced dangerously downward more than two dozen times during the 11-minute flight. The pilots managed to pull the nose back up over and over until finally losing control, leaving the plane, Lion Air Flight 610, to plummet into the ocean at 450 miles per hour, killing all 189 people on board.
The data from the so-called black box is consistent with the theory that investigators have been most focused on: that a computerized system Boeing installed on its latest generation of 737 to prevent the plane’s nose from getting too high and causing a stall instead forced the nose down because of incorrect information it was receiving from sensors on the fuselage.
Details of the black box data were contained in a briefing for the Indonesian Parliament and were first disclosed publicly in the Indonesian media. The data was subsequently posted and analyzed in a blog post by Peter Lemme, a satellite communications expert and former Boeing engineer.
Despite Boeing’s insistence that the proper procedures were in the handbook, also called the emergency checklist, pilots have said since the accident that Boeing had not been clear about one potentially vital difference between the system on the new 737s and the older models. In the older versions, pilots could help address the problem of the nose being forced down improperly — a situation known as “runaway stabilizer trim” — by pulling back on the control column in front of them, the pilots say.
In the latest 737 generation, called the Max, that measure does not work, they said, citing information they have received since the crash. The pilots on Lion Air Flight 610 appear to have forcefully pulled back on their control columns to no avail, before the final dive, according to the information from the flight data recorder.
Capt. Dennis Tajer, spokesman for the American Airlines pilot union and a 737 pilot, said he could not comment on any aspect of the investigation. But, he said, “in the previous model of the 737, pulling back on the control column, Boeing says will stop a stabilizer runaway.”
Information provided to American Airlines from Boeing since the crash, Captain Tajer said, “specifically says that pulling back on the control column in the Max will not stop the runaway if M.C.A.S. is triggered. That is an important difference to know.”
The futile struggle by the pilots to regain control can be seen in colorful jagged lines in graphs contained in the report to the Indonesian Parliament, documenting the seesaw motion of the nose as the system pushed it down at least two dozen before the plane’s fatal nose-dive.
From the moment Flight 610 took off just after dawn from the airport in Jakarta, the Indonesian capital, the Max 8 jet was recording errant data from one of the two angle-of-attack sensors on the nose of the plane that records the pitch at which a plane is climbing or descending.