With flights grounded for nearly five hours Friday evening, Americans heard from the homeland security secretary. They heard from the transportation secretary. They did not hear from President Trump.
At least not about the nationwide ground stop, the first major crisis the federal government has faced since the midterm elections. The halt grounded or delayed some 10,000 flights from coast to coast and confirmed what experts have been warning for years: that the nation’s flight safety system is perilously fragile.
Instead, the president, who remained behind the scenes at the White House, posted messages to social media that night on other topics.
“MAKE OUR ENTERTAINMENT INDUSTRY GREAT AGAIN!” he wrote on Truth Social, in the middle of the crisis, calling for tax incentives to lure movie production back to the United States.
The absence of Mr. Trump, who has made few public appearances since Democrats swept the midterms, seemed notable enough that Markwayne Mullin, the homeland security secretary, sought to assure the nation in the heat of the crisis on Friday night that the president was fully engaged, if not in his more common spot in front of the cameras.
“This is what President Trump does,” Mr. Mullin said in a news conference. “He puts leaders in place, and he allows them to lead. They even ask, you know, why is the president not talking? It’s because he’s allowed Secretary Duffy and us to go out there and explain to you what took place.” He was referring to Sean Duffy, the transportation secretary, who appeared beside Mr. Mullin on Friday night.
By Saturday morning, Mr. Trump still hadn’t commented on the ground stop. Instead, he began attacking Gov. Gavin Newsom of California, a Democrat and political rival, over his commutation of death penalty sentences for more than 500 inmates, an action the governor took more than a week ago.
It is an old strategy in politics to let underlings be the bearers of bad news. Mr. Trump’s decision not to engage in public on a crisis with cascading effects across the country comes as Democrats in Congress have already vowed to investigate the administration’s handling of the shutdown.
With Mr. Trump steering clear of the topic on Friday night, Mr. Mullin and Mr. Duffy appeared at times to contradict each other as they tried to explain the breakdown that affected tens of thousands of people.
Transportation Department officials, in particular, were caught off guard when Mr. Mullin told reporters that the meltdown had occurred because new technology upgrades had “overwhelmed the older system,” according to two people familiar with the matter.
At the time, department officials had not made a determination of what precisely had overloaded the antiquated system and caused the meltdown to spiral across the country. Mr. Duffy also tried to gently redirect after Mr. Mullin’s remarks, stressing that old equipment, not new technology, was what had overloaded and failed. On Saturday, Mr. Duffy told reporters that a routine router replacement in a remote area had triggered the nationwide outages but officials could not yet say whether it had been because of a faulty part or a contractor error.
In a statement on Saturday, Mr. Duffy said: “We’re deeply grateful for Secretary Mullin and his team’s partnership as we worked through this challenging time.”
When asked where Mr. Trump was during the ground stop, the officials defended the president and heaped praise on him.
“Well, the two of us have talked to him,” Mr. Duffy said. “He’s in. I’ve talked to him on the phone. I’ve talked to him in the Oval. So has Markwayne.”
As the agency leaders addressed the media, Stephen Miller, the newly installed White House chief of staff, and Steven Cheung, the communications director, watched off to the side.
Asked for comment, the White House referred to the comments of Mr. Duffy and Mr. Mullin.
Mr. Duffy said Congress was to blame for the ground stop because the legislative branch had failed to fund updated technology for the Federal Aviation Administration. Lawmakers have privately questioned how efficiently the F.A.A. has spent money already appropriated, congressional aides say, and Democrats say the administration has prioritized issues like deportations over air safety.
“I want $50 billion,” Mr. Duffy said. “President Trump is a builder. He’s going to build this network and deliver for the American people.”
He added: “And when Secretary Duffy said he’s the greatest president we’ve had. You’ve never had a builder and a leader like President Trump lead this nation, have a vision and put the team together.”
Ever since Republicans were routed in the midterm elections, Mr. Trump has been keeping somewhat of a lower profile. Before the midterms, he embarked on a blitz of rallies across the country in which he spoke to the public nearly every night.
This week, he appeared in public sparingly: once at an impromptu appearance with the U.F.C. president Dana White as a follow-up to a post that Mr. Trump acknowledged was an attempt to distract from bad news cycles, and at a speech on Veterans Day.
Former Representative Marjorie Taylor Greene, Republican of Georgia, who was once a close ally of the president’s, noted that Mr. Trump has never been shy in putting his full focus on his construction projects, such as the attempted repairs to the Lincoln Memorial Reflecting Pool. But she noted that he seemed unengaged during the F.A.A. crisis.
“Trump constantly railed about fixing the reflection pool so much that he used the last day before massively losing the midterms to give a speech in front of the reflection pool bragging about he fixed the reflection pool,” she wrote on social media. But in a crisis that led to Mr. Duffy’s call for billions to upgrade air traffic systems, she wrote, “President Trump doesn’t even issue so much as a Truth Social post.”
She added: “While everyone was freaking out thinking we are under some sort of attack, Trump didn’t even bother to address the nation.”
On Saturday afternoon, Mr. Trump finally publicly acknowledged the matter, but only obliquely and through another’s words. He posted a quote attributed to Senator John Kennedy, Republican of Louisiana, that appeared to reference a desire for more funding for the F.A.A.: “The FAA Funding should be a stand alone Bill — We should get Democrat support for that!”
With the crisis largely over, though with many flights still canceled and disruption rife, the president posted again about the need for tax credits for the movie industry.
Maggie Haberman, Karoun Demirjian and Kate Kelly contributed reporting.
