The transportation secretary, Peter Buttigieg, is facing backlash for the debacle at the Federal Aviation Administration that saw the agency’s key air missions software go off line, adding one more disappointment to the career of a rising star in the Democratic Party. 

The system, known as the Notice to Air Missions system, went offline Wednesday. The software is used to alert pilots about closed runways, weather emergencies, and general safety hazards.

This left tens of thousands of passengers waiting in terminals across the country, unsure of when they would be able to depart. Mr. Buttigieg said that the nationwide “ground stop” order halting all flights was issued “out of an abundance of caution” as the FAA worked to resolve the issue. 

Mr. Buttigieg was rewarded for his support of President Biden during the Democratic presidential primary with a Cabinet position that allows him to oversee transportation grants, rule-making, and the implementation of the bipartisan infrastructure bill. His presidential ambitions, though, could be hampered by a series of missteps, highlighted by the recent FAA debacle. 

Conservatives have taken issue with Mr. Buttigieg’s use of private aircraft and advancement of racial equity in transportation policy. 

In April, the transportation secretary took a government-owned jet to New York from Washington for a one-day trip to meet with the head of the ACLU and to appear on rapper Charlamagne tha God’s radio program, the Breakfast Club — a frequent stop for Democratic presidential candidates. 

A report from Fox News Digital found that Mr. Buttigieg has traveled by private jet at least 18 times since being sworn in, all on the taxpayer’s dime. Before becoming a Cabinet member, the former mayor spent more than $300,000 on private jets during his failed presidential campaign. A former secretary of health and human services, Tom Price, was forced to resign over similar practices in 2017. 

One of the most perilous transportation-related moments of the Biden administration was when America’s railways were threatened by a possible strike. Last year, unions representing a majority of the country’s rail workers voted to reject a contract with the government, leading to the very real possibility of supply chains halting nationwide. 

At the time, the labor secretary, Marty Walsh, was busy working on a new contract before Congress stepped in to enforce the current agreement. As all of this was playing out, Secretary Buttigieg took a week-long vacation to Porto in northern Portugal. 

Mr. Buttigieg also garnered headlines in 2021 for advancing racial equity in transportation policy. “We are strengthening our Disadvantaged Business Enterprise Program, to ensure that business opportunities in transportation and infrastructure reach women- and minority-owned small businesses,” the secretary wrote in a message at the time. 

Governor DeSantis derided the secretary. “There’s trees they’re putting in, they’re saying that highways are racially discriminatory. I don’t know how a road can be that,” Mr. DeSantis said after the transportation department’s announcement. 

Mr. Buttigieg has also faced criticism from fellow Democrats. Over the holidays, Southwest Airlines canceled thousands of flights, leaving Americans stranded in airports across the country. 

Liberals in Congress chided the secretary for not heeding their advice. “Nearly six months ago, Bernie Sanders and I called for Buttigieg to implement fines and penalties on airlines for canceling flights,” Congressman Ro Khanna said in a tweet. “Why were these recommendations not followed?”

Senator Sanders also wrote Mr. Buttigieg a letter in June describing a number of key actions he could unilaterally take as transportation secretary to reduce cancellations and ensure refunds for passengers. Mr. Sanders’s suggestions went unheeded. 

Shortly after Mr. Khanna’s tweet, Mr. Buttigieg’s husband, Chasten, said the California congressman was grandstanding. “Zero tweets on his timeline about Southwest leadership or their outdated IT systems. That’s politics, I guess,” the secretary’s husband said. 

Mr. Buttigieg likely will not be satisfied to go into retirement with the title “transportation secretary” at the top of his resume, but these high-profile mistakes in what is usually a low-key position threaten his presidential ambitions.