The ban on the Boeing 737 MAX aircraft became worldwide on Wednesday after US President Donald Trump joined Canada and other countries in grounding the aircraft amid intense pressure about the safety concerns.
Demands grew for urgent answers over the safety of the Boeing 737 MAX 8 as Ethiopian and US authorities searched for the cause of Sunday's deadly crash near the capital of the African nation, which followed a fatal accident in Indonesia in October.
"We're going to be issuing an emergency order of prohibition to ground all flights of the 737 MAX 8 and the 737 MAX 9 planes," Trump told reporters at the White House.
"The safety of the American people and all peoples is our paramount concern."
The Federal Aviation Administration said the decision was based on new evidence gathered at the crash site near Addis Ababa as well as "newly refined satellite data."
Earlier on Wednesday, Canada also joined the long list of countries to ban the plane from flying in its airspace and many airlines have voluntarily taken it out of service.
The FAA said it will continue to work with investigators to determine the cause of the crash, while Ethiopia said it would send the black boxes to Europe for analysis.
"Hopefully they will come up with an answer but until they do the planes are grounded," Trump said of the planes.
Boeing chief Dennis Muilenburg said he supported the US decision "out of an abundance of caution," but continues to have "full confidence" in the safety of the plane.
The company continues its efforts "to understand the cause of the accidents in partnership with the investigators, deploy safety enhancements and help ensure this does not happen again," Muilenburg said in a statement.
Preliminary accounts of the Ethiopian Airlines flight appear similar to the Lion Air crash in October, which were echoed in concerns registered by US pilots on how the MAX 8 behaves.
- Pilots concerns -
At least four American pilots made reports following the Lion Air crash, all complaining the aircraft suddenly pitched downward shortly after takeoff, according to documents reviewed by AFP on the Aviation Safety Reporting System, a voluntary incident database maintained by NASA.
In two anonymous reports on flights just after the Lion Air crash, pilots disconnected the autopilot and corrected the plane's trajectory.
One said the flight crew reviewed the incident "at length... but can't think of any reason the aircraft would pitch nose-down so aggressively."
It was unclear if US transportation authorities review the database or investigate the incidents, however the FAA said this week it had mandated Boeing update its flight software and training on the aircraft.
Questions on the Lion Air crash have honed in on an automated stall prevention system, the MCAS, designed to automatically point the nose of the plane downward if it is in danger of stalling.
According to the flight data recorder, the pilots of Lion Air Flight 610 struggled to control the aircraft as the automated MCAS system repeatedly pushed the plane's nose down following takeoff.
The Ethiopian Airlines pilots reported similar difficulties before their aircraft plunged into the ground.
Boeing came in for criticism after the Lion Air crash for allegedly failing to adequately inform 737 pilots about the functioning of the anti-stalling system.
Ethiopian Airlines CEO Tewolde GebreMariam on Sunday said the captain on the flight, Yared Mulugeta Getachew, 29, was an experienced aviator with more than 8,000 flight hours.
Speaking to CNN on Wednesday, Tewolde said there were "significant similarities" between the Lion Air and ET 302 crashes.
"There are a lot of questions to be answered on the airplane," and he later called for all Boeing 737 MAX models to be grounded.
- Banned from the skies -
In Ethiopia, distraught families wept and lit candles as they visited the deep black crater where the plane smashed into a field, killing 157 passengers and crew, an AFP correspondent said.
Ethiopian Airlines said it would decide by Thursday which country would examine the cockpit voice recorder and flight data recorder recovered from the ill-fated Flight ET 302, spokesman Asrat Begashaw told AFP.
"We are going to send it to Europe but the country is not specified yet," Asrat said.
The airline said Ethiopia does not have the equipment to read the black box data that could provide crucial information about what happened.
The Ethiopian Airlines 737 MAX 8 was less than four months old when it went down six minutes into a flight from Addis Ababa to Nairobi on Sunday, disintegrating on impact.
Asrat said families of the victims from Kenya, China, America, and Canada, as well as diplomatic staff from embassies, were visiting the crash site.
Canada Transport Minister Marc Garneau said Ottawa made the decision to close the country's airspace to the plane given the similarities between the Ethiopian crash and the Lion Air accident.
A dozen airlines have grounded the plane, while Nigeria, Lebanon, Egypt, Serbia, Vietnam, New Zealand and Hong Kong on Wednesday became the latest countries to ban it from their airspace.
The European Union and major hubs such as the United Arab Emirates and Australia had already done so.
American Airlines said it was informed of the FAA decision earlier in the day and had 24 aircraft affected by the US ban, while Southwest Airlines said it was still confirming the move.
Low-cost airline Norwegian Air Shuttle has said it will demand financial compensation from Boeing as the implications of the mass grounding for the airline industry remained unclear.
The MAX series, which is Boeing's fastest-selling model, with more than 5,000 orders placed to date from about 100 customers. There are about 350 MAX 8s in service around the world.
Thomas Anthony, head of the Aviation Safety and Security Program at the University of Southern California, said increasing automation of planes means crews have less experience flying manually.
"So it's not just a mechanical, it is not just a software problem, but it is a problem of communication and trust," he said.