Boeing 737 Max 8: safe to fly?

U.S. officials on Monday expressed confidence in the Boeing-made jetliner involved in Sunday's fatal Ethiopia Airlines crash and said they see no reason so far to restrict them from flying.

The Federal Aviation Administration issued a "continued air worthiness notification" to the international community for Boeing 737 Max operators. The notification essentially says that U.S. regulators think the aircraft is safe to operate but that the agency will take additional action if it receives information that indicates otherwise.

With 34 planes, Southwest Airlines has the largest number of Boeing 737 Max 8s in the world. Air Canada and American Airlines each have 24. United does not operate any Boeing 737 Max 8s aircraft, but it does fly the 737 Max 9. Delta and Sun Country do not fly any 737 Maxs.

The national airlines of Mexico and Argentina suspended the operation of their MAX 8 planes, Reuters reported. Already airlines in Ethiopia, Mexico, China, Brazil, Cayman Islands, South Africa, Morocco and Indonesia have temporarily grounded their Max 8s.

Ethiopian Airlines decided to ground its remaining four 737 Max 8s until further notice.

Several U.S. carriers said they would keep flying the aircraft, including Southwest and American. Air Canada is also continuing to fly the planes.

The 737 is the bestselling airliner in history, and the Max, the newest version of it with more fuel-efficient engines, is a central part of Boeing's strategy to compete with European rival Airbus.