Britain, France and Germany joined a growing list of countries to ban Boeing 737 MAX planes from their airspace on Tuesday as airlines around the world grounded the jets following a second deadly accident in just five months.
On Sunday a new Ethiopian Airlines 737 MAX 8 went down minutes into a flight to Nairobi, killing all 157 people on board, from 35 countries.
In October, a Lion Air jet of the same model crashed in Indonesia, killing 189 -- but no evidence has emerged to link the two incidents.
The widening airspace closures puts pressure on Boeing, the world's biggest planemaker, to prove 737 MAX planes are safe as increasing numbers of fleets have been grounded.
Low-cost airline Norwegian Air Shuttle, South Korea's Eastar Jet and South Africa's Comair also said they would halt flights, but the full extent of the impact on international travel routes was unclear.
On Twitter, US President Donald Trump weighed in on the probe investigating the Ethiopian Airlines crash, writing: "Airplanes are becoming far too complex to fly." "Pilot are no longer needed, but rather computer scientists from MIT," he wrote, referring to the prestigious university in Massachusetts.
US carriers have so far appeared to maintain confidence in Boeing, which has said it is certain the planes are safe to fly.
The move was not enough to reassure the UK Civil Aviation Authority, which said in a statement headlined "Boeing 737 MAX Aircraft" that it was banning the planes from UK airspace "as a precautionary measure".
China, a hugely important market for Boeing, had already ordered domestic airlines to suspend operations of the plane on Monday, as did Indonesia.
But several airlines said they were not cancelling MAX 8 flights.
"The Boeing 737 MAX is a highly sophisticated aircraft," said India's SpiceJet, which has 13 of the MAX 8 variants in its 75-strong fleet.
"It has flown hundreds of thousands of hours globally and some of the world's largest airlines are flying this aircraft," it said in a statement.
Boeing has described the MAX series as its fastest-selling family of planes, with more than 5,000 orders placed to date from about 100 customers.
But not since the 1970s -- when the McDonnell Douglas DC-10 suffered successive fatal incidents -- has a new model been involved in two deadly accidents in such a short period.
The weekend crash sent Boeing shares nosediving as much as 12 percent on Monday, wiping billions of dollars off the market value of the company.
"I think the impact for the industry is significant," said Gerry Soejatman, a Jakarta-based aviation analyst.
"We have a new type of aircraft -- that type of aircraft has only been in service for two years -- and... we have two accidents with seemingly similar circumstances."
The plane involved in Sunday's crash was less than four months old, with Ethiopian Airlines saying it was delivered on November 15.
It went down near the village of Tulu Fara, some 40 miles (60 kilometres) east of Addis Ababa.
Inhabitants of the remote area looked on from behind a security cordon as inspectors searched the crash site and excavated it with a mechanical digger.
Ethiopian Airlines said the pilot was given clearance to turn around after indicating problems shortly before the plane disappeared from radar.
The airline's chief executive Tewolde GebreMariam said the plane had flown in from Johannesburg early Sunday, spent three hours in Addis and was "dispatched with no remark", meaning no problems were flagged.
Investigators have recovered the black box flight recorders, which could potentially provide information about what happened, depending on their condition.
Delegates hugged and comforted one another as they arrived at the meeting with the UN flag flying at half-mast.
Other passengers included tourists and business travellers.
Kenya had the highest death toll among the nationalities on the flight with 32, according to Ethiopian Airlines. Canada was next with 18 victims. There were also passengers Ethiopia, Italy, the United States, Britain and France.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)