Investigators have recovered the two black boxes from the crash site, which should provide information about what brought down Nairobi, Kenya-bound Ethiopian Airlines Flight 302. That Boeing 737 Max 8 crashed in a rural area outside of Addis Ababa shortly after takeoff, killing all 157 passengers and crew, less than five months after the crash of a Lion Air plane in Indonesia. On Oct. 29, Lion Air Flight 610 plunged into the Java Sea minutes into its flight from Jakarta, Indonesia, killing the 189 people on board.
Bassani said the union told flight attendants that they don't have to work on a plane they don't feel comfortable flying on.
American's pilots' union said it contacted company executives about the group's "critical safety concerns" after the crash.
"It is important for you to know that if you feel it is unsafe to work the 737 Max, you will not be forced to fly it," the Allied Pilots Association told its members Tuesday.
There are more than 370 Boeing 737 Max planes flying worldwide, 74 within the United States, the FAA said.
The pilots of the doomed Lion Air plane appeared to be battling an automated anti-stall system that isn't on older models of the 737, which ended up repeatedly pushing the nose of the plane down, investigators have indicated. Boeing said on Monday that it is developing software fixes as well as updating training procedures and manuals — moves that the FAA expects to mandate no later than April.
While the cause of either crash has not been determined, the Association of Flight Attendants-CWA, which represents some 50,000 flight attendants, including United's, urged the FAA to ground the planes as a precaution.
"The United States has the safest aviation system in the world, but Americans are looking for leadership in this time of uncertainty," Sara Nelson, AFA's international president, said in a statement.
"The FAA's April deadline for updates is insufficient considering the legitimate fear and uncertainty following two deadly accidents involving this aircraft," Nelson added. "The FAA must restore public confidence by grounding the 737 Max until the required changes have been implemented and the public can be fully assured."
The FAA on Tuesday reiterated its decision not to ground the planes, saying its review "shows no systemic performance issues" to warrant the planes be taken out of service.