Ethiopian Airlines flight 302's damaged flight data recorder. (Bureau d’Enquêtes et d’Analyses)
One-off accidents are tragic, but the biggest concern for regulators, carriers and manufacturers is an underlying issue that could cause multiple disasters. Despite the cursory appearance of an eerie similarity to the October Lion Air flight that killed 189 people, the FAA said there was nothing to link it to last Sunday's deadly Ethiopian Airlines flight.
Now, that has changed.
Investigations typically take up to a year or more, with information slow to come out. But the high profile of the Ethiopian Airlines flight that crashed minutes after takeoff, killing 157, and the worldwide effect on aviation as the aircraft is featured in dozens of carriers' fleets, has put pressure on that timeline. Information trickling out has provided insight into the global grounding of the Boeing 737 MAX that featured in both crashed.
"There was not an obvious link ... initially," said Acting FAA Administrator Daniel Elwell in an interview on CNBC.
The original flight track that the FAA received from Aireon, based on the raw space-based ADS-B data, was not similar enough to warrant action. Wednesday, however, a longer and more refined track was sent which "verified that [in ET 302], the track of that airplane was close enough to the track of the Lion Airlines track that went down in the ocean four or five months ago to warrant the grounding of the airplanes," Elwell said.
That was the top reason for the FAA's course reversal, though he also mentioned "evidence on the ground" that "implied it was similar" to the Lion Air flight.
That evidence came in the form of a jackscrew, according to a Bloomberg source on Friday. The recovered device, which is used in aircraft to set trim levels, indicated that the plane was set to dive.
Most other countries around the world had already announced the grounding of the 737 MAX before the U.S. received the information that persuaded it to make that call, but Elwell said the FAA received the data "in practically real time" with the facilitation of Canada, which uses Aireon's subscription service. The FAA could not, he said, find what data other countries were basing their decision on, but global pressure did not factor into the FAA's emergency order.
"I can't speak to the motivations of the other countries, but for us, it was an independent decision," Elwell said.
While this has been going on, ET 302's flight and voice data recorders are in France for analysis, because of sustained damage. The country's Bureau d’Enquêtes et d’Analyses (BEA) is working on extracting information from them.
The BEA has the ET 302 pilot's "panicky" call to controllers at Addis Ababa's Bole International Airport, and the New York Times has spoken with a someone who has reviewed the communications.
“Break break, request back to home,” the captain said. “Request vector for landing.”
Information from the planes black boxes should be released this week, but it may be a while before 737 MAX aircraft are given the go-ahead to fly again.
In the meantime, Boeing has paused delivery — but not production — of its best-selling aircraft and is working on a software update to help smooth out the after-takeoff issues with trim and angle-of-attack sensor information that may have played a role in the two crashes.