President Trump announced that the United States founded the Boeing 737 Max aircraft and twisted an earlier decision by US regulators to keep the jets flying in the wake of a second fatal crash in Ethiopia.
The federal department had for days opposite conversations to the ground plane, even as security regulators in about 42 countries had banned flights by jets. As recently as Tuesday, the agency said it had seen "no systemic performance problems" that would stop air traffic.
"The security of the American people, for all people, is our primary concern". Trump told journalists in the White House.
The order came hours after Canada's Transport Minister said that recently available satellite tracking data suggested similarities between the crash in Ethiopia and another accident in October last year. In a statement released after Mr. Trump's announcement, F.A.A.
Marc Garneau, Canada's Transport Minister, had said that the satellite tracking data from the vertical path of the Ethiopian jet engine at start and comparable lion air crash data showed similar "vertical fluctuations" and "fluctuations".
The American and Canadian decisions also come after Ethiopian Airlines said that one of two pilots on Sunday flights reported flight control problems to controllers minutes before the aircraft crashed and told controllers he wanted to return to Bole International Airport in Addis Ababa. The pilot was cleared to do so, three minutes before the contact was lost with the cockpit, a spokesman for the airline said Wednesday.
The disclosure suggests that a problem with the handling of the aircraft or the computerized flight control system could have been a factor. There has been no proposal for terrorism or other external influence on the aircraft's function, which was only a few months old.
[ Read the latest updates about the crash and Fallout.]
Officials investigating the Lion Air crash have enabled a new flight control system to have contributed to the previous one accident. When they banned flights with the aircraft this week, some safety regulators stated that pilots would not be able to handle the aircraft if they received incorrect signals from key flight instruments.
The accidents have set Boeing on the defensive. 737 Max is Boeing's best-selling jet ever and is expected to be an important driving force for profit with about 5,000 of the order plans. The shares have fallen about 13 percent a week.
After Indonesia's crash, Boeing was expected to update its program and training guidelines so that airlines can teach their pilots to fly the plan more safely and easily. The program update is scheduled for April.
"Boeing is an incredible company," Trump said. "They work very much very right now and hopefully they will get the answer quickly, but until they do, the plan is grounded."
Tuesday morning, Boeing's CEO Dennis A. Muilenburg, had called Mr. Trump to personally express his confidence in the animals' security, according to two people who informed the call.
The short conversation had already been in effect, but soon after Mr. Trump raised himself worrying that aircraft became too complex to fly and thus threatened passengers. "Pilots no longer need, but rather computer scientists from MIT" he wrote on Twitter.
Boeing said it supported the decision to grind the plan.
"We support this proactive step from an abundance of caution," says Mr Muilenburg. "We do everything we can to understand the cause of the accidents in partnership with investigators, implement safety improvements, and make sure it doesn't happen again."