Several days after an Ethio­pian Airlines Boeing 737 Max 8 crashed outside Ethio­pia’s capital city, the Trump administration’s senior air safety official was still defending the plane.

Acting Federal Aviation Administration chief Daniel K. Elwell, a former Air Force command pilot and American Airlines captain, was reassuring the House chairman who oversees aviation safety about the soundness of the jet, even though the same model had crashed in Indonesia four months earlier.

“He still had confidence in the plane,” Rep. Peter A. DeFazio (D-Ore.), chairman of the House Committee on Transportation and Infrastructure, said of the conversation early Wednesday. DeFazio said Elwell agreed to return that afternoon to address growing concerns. “Then they went dark.”

Late Wednesday morning, Canada’s transportation minister announced that new satellite tracking data showed enough similarities between the October incident and the March 10 crash to ground the aircraft, following numerous other countries that had already made the decision. That left the United States as a glaring holdout.

Finally, at 2:30 p.m. Wednesday, word came from President Trump that the United States would also bar the planes from flying.

“I didn’t want to take any chances,” Trump said.

It was extraordinary for a president to intervene in matters typically left to the FAA or the Department of Transportation. Asked whether President Barack Obama was ever directly involved in a decision to ground planes or issue urgent safety mandates during his tenure, former transportation secretary Anthony Foxx said, “No, never, not one time.”

In public and in private, Trump presented himself as a key arbiter in deciding whether the Boeing 737 Max 8 and 9 planes would be able to keep flying, according to White House and administration officials interviewed for this report, who spoke on the condition of anonymity to candidly discuss internal deliberations.

Rather than simply being briefed on the FAA’s findings in the days after the crash, Trump played an active role, participating in phone calls with Boeing chief executive Dennis Muilenburg and other stakeholders, and offering his thoughts about the aviation industry. Asked by reporters about the decision to ground the plane, Trump left the impression that he had taken the lead, saying it was a “very tough decision.”

But in the days that followed, as Trump faced criticism about whether his administration acted too slowly and whether he should have been so involved, the White House sought to direct attention back to the aviation agency.

A senior White House official said the FAA had repeatedly told the president by phone that there was no reason to ground the planes and that Boeing had a record for being safe. This official said the FAA showed the president how many Boeing planes were in the sky, told him that the particular model had been flying for years, and urged against a quick grounding.

An FAA spokesman declined to discuss what was communicated to the president. But agency officials offered various versions of this statement, to the public as well as others in government: “All available data . . . shows no systemic performance issues and provides no basis to order grounding the aircraft.”

The disagreement offers a window into the broader dysfunction that can result when the highly technical realm of crash investigations is made political.

After Trump jumped in, some of the signature features of his presidency washed over the process. The typically plodding, data-driven forensic work of figuring out what caused an airplane to fall from the sky has given way to attention-grabbing tweets, administration infighting and questions of government competence, critics said.

At the same time, critics said FAA officials were more stubborn than valiant in their initial refusal to act and that they were too deferential to Boeing.

“When we say we have no basis to ground the aircraft, we have no basis to ground the aircraft,” said one FAA official to The Washington Post on Tuesday, when the European Union and others were breaking with the United States and grounding the aircraft. The official requested anonymity because they were not authorized to speak publicly about the situation.

“You had data. You had 350 dead bodies in four months,” countered a former FAA official, who requested anonymity to speak candidly about the agency’s approach.

It’s a remarkable situation for the FAA — and a test of the agency’s standing at a time when commercial flight in the United States is historically safe.

Joseph LoVecchio, a retired airline captain with 31 years of experience flying major carriers and jets including the Boeing 737, said the FAA’s oversight of Boeing’s training and documentation for a key automation feature was flawed. That feature has been blamed, in part, for the crash of the Boeing 737 Max 8 in Indonesia in October. On Sunday, Ethiopia’s transportation minister said information from the flight data recorder from the Ethiopian Airlines jet shows “clear similarities” to the Lion Air flight.

“Of all the years of building aircraft and certifying them, how can something like that slip through the cracks? That was a failure of leadership,” LoVecchio said.

But Ray LaHood, a former GOP congressman from Illinois, who also served as a transportation secretary under Obama, emphasized that most FAA staff members are career employees focused on ensuring that the U.S. aviation system is as safe as possible. Once potential problems with the planes are fixed, “I think this will be a small little blip on the total reputation of the agency,” he said.

As transportation secretary in 2013, LaHood made the decision to ground Boeing’s 787 Dreamliner after two instances in which the plane’s lithium-ion batteries caught fire. There was much internal debate at the FAA at the time, with the agency’s safety officials questioning LaHood’s decision, which took the planes out of commission for about three months.

The decision to ground the Max 8 and 9 planes was made with an emergency order under Elwell’s signature.

New physical evidence discovered at the crash site, “together with newly refined satellite data available to FAA this morning, led us — led me — to this decision,” Elwell told reporters shortly after Trump spoke Wednesday.

White House economic adviser Larry Kudlow said decisions on the planes were made at the Transportation Department by “Secretary Elaine Chao, who is a very brilliant woman, working with the FAA.”

Elwell, who said he was in “constant consultation” with Chao, presented the new data as a late-breaking, game-changing development that required a major reversal.

U.S. officials had been telling American travelers, and those around the world, that it was safe to keep flying on the 737 Max jets, despite flight bans and growing concerns in other countries, from China to the United Kingdom. But officials were now saying that new information required the planes to be grounded immediately.

Aviation experts said the satellite data showed Ethio­pian Airlines Flight 302 had ascended and descended multiple times after takeoff, echoing the behavior of the plane in the Oct. 29 Lion Air flight that crashed into the Java Sea after sensor and automation malfunctions, according to the preliminary investigation.

Speaking to reporters on Wednesday, Elwell said the information provided crucial “missing pieces that we did not have prior to today.”

But the data buttressing one of those missing pieces had actually been in the FAA’s hands since Monday, according to an FAA official and another source familiar with the details.

The explanation for the delays involving the critical information are in dispute, as is the propriety of the hands-on approach Trump initially took before he began distancing himself as the week progressed.

An administration official argued that the FAA had originally been dismissive of the satellite data, reflecting the agency’s strong push to defend well-connected Boeing’s safety record.

But another person familiar with the circumstances denied that, saying the agency wasn’t dismissive but instead needed to translate the raw data — which is typically read by computer — into something useful.

An FAA spokesman clarified the timeline, saying that after receiving the data Monday night, the FAA sought additional expertise Tuesday and “received the refined data analysis” Wednesday morning.

Trump had made his own impatience with aviation technology clear in several tweets, when he opined that “airplanes are becoming far too complex” and rely on “unnecessary” technological advancements. “Pilots are no longer needed, but rather computer scientists from MIT,” he tweeted.

In Trump’s unusual step of consulting directly with Muilenburg, a man he referred to in June as a “friend of mine,” the Boeing chief appealed to the president to keep the 737 Max flying. But Trump also told officials that the Boeing 737 “sucked” and wasn’t as good as the Boeing 757 he owns as a personal jet.

Some experts and analysts say they are confident that the decision to ground the Boeing 737 Max was made by experts at the FAA based on the new evidence, which included a device found in the wreckage that indicated the jet was configured to dive. That finding marked another similarity with the Indonesia crash.

But the way the grounding decision was rolled out was highly unusual, the experts said.

“I have never seen the White House come up with an announcement like this,” said Jeff Guzzetti, who until last month was director of the FAA’s Accident Investigation Division. “They may have felt that the world’s attention was focused on this and the White House” deserved its share, Guzzetti said. “The Canadians beat them to it. It did look bad.”

Trump was inclined to ground the planes in meetings early in the week but was getting sharp pushback from Muilenburg and FAA officials, who continued to deliberate as late as Wednesday morning, officials said.

A person familiar with the process said Trump quizzed Elwell and Chao about why other countries were grounding the planes and the United States was not. “The answer was, ‘There’s no basis,’ ” the person said.

Christopher A. Hart, the former chairman of the National Transportation Safety Board, said he did not disagree with the FAA’s hesitance to ground the planes.

Hart said the grounding of the 737 Max represented “uncharted territory” for the United States and one of its plane manufacturers. What is the threshold for grounding a plane in a scenario where automation doesn’t work as intended or pilots fail to grasp the complexities of automated systems, he wondered.

“The two questions are going to be: What is the trigger for the grounding? And what is going to be the trigger for ending the grounding?” Hart said.

Kudlow said “Boeing has come forward to make some adjustments in flight plans and software and sensors and pilot training and all kinds of things.” Still, he added, “They won’t be back on the runways until we are absolutely 100 percent satisfied that they are safe.”

Trump told reporters on Wednesday that he had been having phone conversations with airline executives and regulators throughout the process.

The White House didn’t get the satellite data until Wednesday, an administration official said. Trump had a final phone consultation with Muilenburg that day.

Trump agreed to let the FAA announce the decision but then did it himself before the FAA could.

“They were going to announce grounding the plane, but they told Trump they were going to do that and Trump went out and announced it before I heard from the FAA,” DeFazio said.

After telling reporters the planes were being grounded “effective immediately,” Trump went off script, indicating it was not solely a safety-based decision.

“We didn’t have to make this decision today. We could’ve delayed it,” Trump said. “We maybe didn’t have to make it at all, but I felt — I felt — it was important, both psychologically and a lot of other ways,” Trump said.

Lori Aratani, Faiz Siddiqui, Toluse Olorunnipa, Damian Paletta and Todd Frankel contributed to this report.