The FAA said its order was prompted by new evidence from the Ethiopian Airlines crash site gathered on Wednesday which, together with newly-refined satellite data of the aircraft's flight path, indicated similarities with the Lion Air flight which killed all 189 people on board on Oct 29 previous year.
With all Boeing 737-800 Max aircraft set to stop operating in Indian airspace from 4 p.m. on Wednesday, the Civil Aviation Ministry has called a meeting of various airlines to keep a check on fares from spiralling.
The news had left the United States and its carriers as the last major users of the aircraft.
Prior to Wednesday's announcement, the FAA had said there was no basis to ground the Boeing 737 Max 8 planes.
Until Trump's announcement, the US Federal Aviation Administration (FAA) had said that it didn't have any data to show the jets were unsafe, even though many nations had already banned them from their airspace.
In October, an Indonesian Lion Air Flight, which was also a Boeing 737 Max 8, crashed and killed all 189 people on board.
Several US lawmakers said they would issue subpoenas to regulators, including the FAA's Elwell, as well as Boeing executives, to testify before Congress.
Fresh information from the wreckage in Ethiopia and newly refined data about the plane's flight path indicated some similarities between the two disasters "that warrant further investigation of the possibility of a shared cause", the FAA said in a statement.
Flight Global's Mr Taylor said it now looks more likely the grounding "will extend at least a few weeks, and potentially into a few months, but it all depends on what safety issues are identified".More news: Beto O'Rourke leaps into 2020 Democratic presidential race
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Tewolde said he is confident the "investigation will reveal that the crash is not related to Ethiopian Airlines' safety record".
Trump said his emergency order would go into effect immediately and all planes in the air would be grounded upon landing at their destinations.
UNITED STATESPilots in the USA had expressed safety concerns about the Boeing 737 Max 8 to the authorities, reports have said.
The FAA had previously held out while many countries banned the aircraft.
"Based on the information now available, we do not have any basis to issue new guidance to operators", Boeing said in a statement.
Last October, a MAX 8 operated by Lion Air crashed 12 minutes after takeoff from Jakarta, Indonesia.
Ellis Taylor, Asia Finance Editor at Flight Global, said the grounding of the aircraft "will have some impact" on U.S. schedules.
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Southwest is the world's largest operator of the 737 MAX 8 with 34 jets. He said the data provides an indication of the plane's course and its vertical profile. The pilot attempted to stop the software and correct the plane, but ultimately, "the pilot lost that fight with the software".
Like Southwest, the Max 8 accounts for a small percentage of American's fleet - 24 planes making 85 flights a day.