Canada’s transport minister also said he will not hesitate to act once the cause of the crash is known.
Two Democratic Senators Dianne Feinstein and Richard Blumenthal called for the immediate grounding of the aircraft, as did Paul Hudson, the president of FlyersRights.org and a member of the FAA Aviation Rulemaking Advisory Committee.
Blumenthal said the planes “should be grounded until the FAA can assure American travelers that these planes are safe.”
Sara Nelson, the president of Association of Flight Attendants union, wrote the FAA on Monday asking it to conduct a comprehensive review and “take steps immediately to address concerns and ensure the safety of the 737 MAX fleet.”
The National Transportation Safety Board and the FAA are both at the crash site in Ethiopia, Chao said.
Boeing’s shares fell as much as 10 percent on the prospect that two such crashes in such a short time could reveal flaws in its new plane. Boeing, whose shares closed down 5.3 percent at $400.01 in the heaviest trading trade since July 2013.
The 737 line, which has flown for more than 50 years, is the world’s best-selling modern passenger aircraft and viewed as one of the industry’s most reliable.
China ordered its airlines to ground the jet, a move followed by Indonesia, Singapore and Ethiopia. Other airlines, from North America to the Middle East, kept flying the 737 MAX 8 on Monday after Boeing said it was safe.