The Federal Aviation Administration advanced a rule Thursday that would give flight attendants an extra hour of rest, guaranteeing a minimum of 10 hours off the clock between shifts.

Congress ordered the change in 2018, but the Trump administration slow-walked the proposed rule, sending it through an additional step in the approval process. It was published on the FAA’s website as Administrator Stephen Dickson was preparing to face questions Thursday from the House Transportation Committee on aviation safety.

“Flight attendants are incredibly stressed with the conditions in the air now,” said committee chairman Rep. Peter A. DeFazio (D-Ore.). “They’re overworked, they’re tired, and we don’t have that rule in place yet.”

Current rules generally require that flight attendants get nine consecutive hours off between shifts of up to 14 hours, although that can be reduced in some circumstances. After Congress ordered the extra hour, many airlines began offering the 10 hours, according to the FAA.

The measure has the backing of labor unions, but Airlines for America, an industry organization, said it could cost carriers upward of $750 million in the coming decade due to additional costs including training and travel.

The rule is moving forward at a time when some airlines are stretched thin as they seek to recover from the coronavirus pandemic and handle a surge in incidents of unruly passengers. Sara Nelson, president of the Association of Flight Attendants, said the rule was needed “yesterday.”

“Flight attendant fatigue is real,” she said in a statement. “It is documented with congressionally mandated fatigue studies and other major health studies. COVID has only exacerbated the safety gap with long duty days, short nights, and combative conditions on planes.”

The FAA said determining the precise benefits of the rule is difficult, but it would likely improve safety and flight attendants’ health. The public can comment on the proposed rule before it is finalized, which could take months.

On the same day the agency advanced the rest rule, Dickson faced questions from lawmakers on other FAA efforts to improve safety.

In December, Congress passed a bill requiring the agency to overhaul its approach to regulating companies like Boeing after investigations into two deadly 737 Max crashes found fault with the government’s oversight of the jet manufacturer.

“It’s a mandate from Congress that the culture at FAA is going to change, the scrutiny is going to change,” DeFazio said Thursday. “It has to change.”

The bill passed with bipartisan support. Rep. Garret Graves (La.), the ranking Republican on the committee’s aviation panel, said it was vital that changes spelled out in the law are put into practice.

“It’s important for us to continue working together to not establish, but to maintain the gold standard that the FAA has, in terms of global aviation safety, and maintain — not establish, but to maintain — the fact that traveling by air is still the safest means of transportation,” Graves said.

Dickson said he began reorienting the agency even before the law was passed and had continued to reiterate to staff that safety was the priority.

“We are not just doing this work because you have directed us to do it,” Dickson said. “We are doing it because it is the right thing to do for aviation safety. This is what the public expects and it is the standard we have set for ourselves.”

The law gives the FAA new power to oversee safety work that companies are permitted to carry out using their own employees. Dickson said the agency had pulled back some of Boeing’s responsibilities, instead conducting checks using government staff. Family members of the Boeing Max crash victims had petitioned Dickson to go further this week and end Boeing’s role altogether.

The two crashes killed 346 people and threw the FAA and Boeing into a crisis as engineers worked to develop and approve a fix to a system on the planes that had sent them into unrecoverable dives. Investigations after the crashes found the FAA didn’t have a full understanding of the system, and last week a former Boeing employee who worked as a test pilot on the Max program was indicted on a charge that he withheld information from the government.

DeFazio, who has been one of the fiercest critics of both the FAA and Boeing since the crashes, seemed reassured Thursday by Dickson’s testimony.

“I’m liking what I’m hearing,” he said. “Keep it up.”