THERE are still more questions than answers about an Ethiopian Airlines plane that crashed shortly after taking off for Nairobi on Sunday, killing all 157 people on board. Ethiopian authorities said yesterday that they will send the flight recorders recovered from the plane to an as-yet-unspecified European country for analysis.

Here are some questions and answers about the crash, the plane and the investigation:

Q. WHAT IS BOEING DOING IN RESPONSE TO THE CRASHES?

A. While defending the Max as safe, the company promises to upgrade some flight-control software “in the coming weeks”.

Boeing began working on the changes shortly after the Lion Air crash. It is tweaking a system designed to prevent an aerodynamic stall if sensors detect that the plane’s nose is pointed too high and its speed is too slow.

Officials at Lion Air in Indonesia said sensors on their plane produced erroneous information on its last four flights, triggering an automatic nose-down command which the pilots were unable to overcome. The plane plunged into the sea.

A Boeing spokesman said once updated software is installed, the system will rely on data from more than one sensor to trigger a nose-down command. Also, the system won’t repeatedly push the nose down, and it will reduce the magnitude of the change, he said. There will also be more training for pilots.

Q. HAVE THERE BEEN COMPLAINTS ABOUT THE PLANES?

A. Airline pilots on at least two US flights reported that an automated system seemed to cause their Boeing 737 Max planes to tilt down suddenly. The pilots said that soon after engaging the autopilot on Boeing 737 Max 8 planes, the nose tilted down sharply. In both cases, they recovered quickly after disconnecting the autopilot.

As described by the pilots, the problem did not appear related to a new automated anti-stall system that is suspected of contributing to the Lion Air crash in Indonesia.

The pilot reports were filed last year in a database compiled by NASA. They are voluntary safety reports and do not publicly reveal the names of pilots, the airlines or the location of the incidents. It was unclear whether the accounts led to any actions by the FAA or the pilots’ airlines.

Q. ARE AIRLINE EMPLOYEES AND PASSENGERS WORRIED?

A. Patrick Smith, a Boeing 767 pilot who writes a column called “Ask the Pilot”, says passengers ask him if the 737 Max is safe. He tells them it is, and he hasn’t heard of any pilots who worry about flying the plane.

“We have two accidents, we somewhat understand one, and we don’t know what happened in the second case at all,” Smith says. “It’s just too early to be jumping to the conclusion of the plane being defective to the point that it’s unsafe.”

Others don’t want to take any chances. The Association of Professional Flight Attendants, which represents more than 26,000 flight attendants at American Airlines, called on CEO Doug Parker to “strongly consider grounding these planes until an investigation can be performed”.

— AP