After days of resistance, the United States followed nations around the world Wednesday in grounding the Boeing 737 Max 8, the aircraft involved in a deadly crash in Ethiopia on Sunday and another several months ago in Indonesia.

Federal Aviation Administration officials said that airplane tracking data they viewed Wednesday and new evidence from the wreckage of the crash in Ethiopia showed similarities to the crash in Indonesia, leading the agency to ground both the 737 Max 8 and the Max 9, another aircraft in the series.

President Trump announced the abrupt about-face Wednesday, after U.S. officials found themselves nearly alone in allowing the planes to remain in the air.

The Portland International Jetport said the announcement would not affect any flights on Wednesday but Southwest Airlines passengers should check with the airline about flights for the rest of the week.  Southwest sometimes uses the 737 Max 8 on its route between Portland and Baltimore.

As recently as Wednesday morning, both Boeing and the FAA had continued to say it was safe for the planes to fly.

“Any plane currently in the air will go to its destination and thereafter be grounded until further notice,” Trump said at an afternoon news conference. “The safety of the American people, and all people, is our paramount concern.”

But there were growing questions about the slow response to the crisis and whether the nation’s top air-safety officials acted quickly enough to protect the flying public. Trump took the unusual step of consulting personally with Boeing’s chief executive earlier this week.

In the months leading up to the crash of Ethiopian Airlines Flight 302, U.S. pilots had expressed exasperation about the aircraft’s systems, which they said limited their control of the planes, according to a confidential safety reporting system hosted by NASA.

Pilots complained of inadequate training on automation-assisted flying systems, unfamiliarity with the controls, anxiety that prompted them to engage autopilot earlier than normal, and at least two instances where the plane pitched downward or maneuvered against pilots’ inputs. Some of the pilots’ complaints were first reported by the Dallas Morning News.

The FAA denied that the pilots’ complaints were indicative of problems with the automation system that has been cited as a factor in the Indonesia crash, but some pilots specifically noted that system as a possible cause of flight-control problems in their reports to NASA.

Trump’s announcement came hours after one by Canada’s transportation minister grounding the jets. Canada had been the last major holdout besides the United States. China was the first major power to ground the planes, followed by countries around the world. On Tuesday, the European Union and several others did the same. Chinese officials said they acted after the FAA failed to do so.

The FAA’s emergency order Wednesday says the similarities in the Ethiopia and Indonesia tragedies “warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed.”

A McLean, Virginia-based aerospace firm, Aireon, used its plane-tracking technology to help investigators get a clearer idea of the way the Ethiopian Airlines plane was moving and how that compared to the Oct. 29 Lion Air flight, acting FAA administrator Daniel Elwell said.

An initial batch of raw data was essentially too fuzzy to be helpful, and the FAA lacked the ability to refine it into usable form on its own, Elwell said.

But Aireon, with help from Boeing and the National Transportation Safety Board, were able to “refine the initial return of the satellites to create a description of the flight,” Elwell said. “The track of the Ethiopian Airlines flight was very close – and behaved very similarly – to the Lion Air flight.”

Aviation experts said the two planes headed up and down multiple times after takeoff. A preliminary report by Indonesian authorities found that a faulty sensor prompted an automation feature on the plane to repeatedly force the plane to descend, until it crashed and killed all on board.

The investigation into the causes of the Ethiopian Airlines crash is in the earliest stages, and it is not clear whether hardware problems, software problems or some combination of factors caused the crash. Elwell said that “we still have a lot to learn before we can say they were the same cause and effect.”

Elwell also said important “physical evidence” was pulled from the wreckage linking the two flights, though he said he could not describe it because the United States is a party to the active investigation.

Yet that evidence “helped us have more fidelity on the flight track, what was happening during the flight, and that evidence aligns the Ethiopian flight closer to what we know happened in Lion Air,” Elwell said. “That’s about all I can say.”

The order will ground more than 70 aircraft. In the United States, the aircraft is used by American and Southwest airlines, which combined have 58 Max 8s in their fleets. United Airlines has 14 of the Max 9 planes.

Boeing said that it continues to have full confidence in the safety of the Max 8 and Max 9 but that after consulting with the FAA, the NTSB, aviation authorities and its customers, it decided to suspend operations of its global fleet of more than 370 Max aircraft.

“Boeing has determined – out of an abundance of caution and in order to reassure the flying public of the aircraft’s safety – to recommend to the FAA the temporary suspension of operations of the entire global fleet of 371 737 MAX aircraft,” the company said in a statement, adding that it supported the FAA’s decision.

“We are doing everything we can to understand the cause of the accidents in partnership with the investigators, deploy safety enhancements and help ensure this does not happen again,” the company said.

Officials at American Airlines – which, along with a union representing its pilots, had reiterated its belief that the planes were safe to fly – said they were now being grounded out of “an abundance of caution.”

“Our teams will be working to rebook customers as quickly as possible, and we apologize for any inconvenience,” the airline said.

Southwest said it was “immediately complying” with the FAA order, noting that it operates a fleet of more than 750 Boeing 737s and that the 34 Max 8s in its fleet “account for less than five percent of our daily flights.”

“While we remain confident in the MAX 8 after completing more than 88,000 flight hours accrued over 41,000 flights, we support the actions of the FAA and other regulatory agencies and governments across the globe that have asked for further review of the data – including information from the flight data recorder – related to the recent accident involving the MAX 8,” Southwest said.

Canadian Transport Minister Marc Garneau said he issued a “safety notice” grounding the flights Wednesday after newly available satellite data was reviewed.

“My experts have looked at this and compared it to the flight that occurred with Lion Air six months ago in October, and . . . there are similarities that sort of exceed a certain threshold in our minds with respect to the possible cause of what happened in Ethiopia,” Garneau said.

At a Wednesday afternoon news conference, Elwell, of the FAA, said delays in getting the damaged flight-data recorders to a place where information could be retrieved contributed to the agency’s decision to ground the planes. Ethiopia has the capability to read black boxes but not heavily damaged ones as in this case, he said.

The plan was to have them on a plane to France on Wednesday night, he said.

“We had been hopeful all along, with the black boxes being discovered so soon after the incident, that we could get them on a table and start pulling data to help us inform our decision one way or another” about whether to ground the airplanes, Elwell said. “That process was lengthened more than I had hoped, to the point where the boxes still are in Ethiopia. But at least now we have a plan to get them out of country.”

Asked what role U.S. investigators will play in analyzing the black box data, Elwell said, per international protocol, Ethiopia is taking the lead – “their soil, their aircraft, their airline,” he said.

But he said U.S. inspectors have been cooperating with their Ethiopian counterparts from the onset of the tragedy and will continue to do so. “Together, FAA and NTSB are helping [the] Ethiopian accident investigation board,” he said.

The preliminary report on the Oct. 29 Lion Air Flight 610 crash found that a device known as an “angle of attack” sensor had mistakenly indicated the plane’s nose was too high, prompting the plane’s automation software to push the plane downward. The Lion Air pilots fought to raise the plane’s nose but were unable to, sending the plane crashing into the Java Sea.

In November, an American Airlines spokesman said that the airline followed all procedures outlined by Boeing and in an emergency directive from the FAA in the wake of the Lion Air crash.

The airline said Wednesday that it has reviewed data for more than 14,000 flights since the Lion Air crash and has not seen a single anomaly related to the sensor.

“At American, we have not had similar issues regarding an erroneous Angle of Attack during manual flight,” spokesman Ross Feinstein said, responding to questions about pilot complaints and concerns about flying a Max 8.

American’s fleet of 24 Max 8 aircraft first went into operation in November 2017 and have a combined total of more than 46,400 operating hours and nearly 18,000 cycles.

Officials around the world had cited the absence of clear information from the Ethiopian Airlines plane to call for the Boeing jets to be grounded. The data from the two flight recorders are eagerly awaited as investigators look for connections.

After China grounded the plane Monday, most countries followed suit, including much of Europe. Bans were also issued by India, Egypt, Uzbekistan, Turkey and Hong Kong.

Ethiopian Airlines chief executive Tewolde GebreMariam told CNN on Tuesday that the pilot reported “flight control problems” and asked to return to the airport. He cast doubt on the airworthiness of the 737 Max.

“Two major fatal accidents on the same airplane model, brand new airplane model, in six months – so there are a lot of questions to be answered on the airplane,” he said.

In remarks to local media, Tewolde also revealed that pilots received additional training from Boeing to fly the 737 Max after the Lion Air crash.

“After the Lion Air crash, questions were raised, so Boeing sent further instructions that it said pilots should know,” he said, according to the Associated Press. “Those relate to the specific behavior of this specific type of aircraft. As a result, training was given by Boeing, and our pilots have taken it and put it into our manuals.”

Elwell said he expects a software fix developed by Boeing after the Lion Air crash to be finalized in the near future.

“We’re hopeful the final touches and tests and evaluation of the software amendment, or the software addition to the Max, will be ready within a couple months. We have not tied the order specifically to the software patch,” he said.

Elwell said he is “confident that the patch is going to be an enhancement to the system and make it far less likely that crews, if faced with that very anomalous situation, far less likely to have to deal with that particular malfunction. I’m looking forward to getting that implemented.”