Metro’s long history of deficiencies — including poor maintenance, a loose safety culture, a blindness to potential hazards and a chronic failure to learn from previous disasters — all contributed to last year’s deadly smoke crisis in a Yellow Line tunnel, federal officials said Tuesday in a report that reads like an indictment of the beleaguered transit agency.

“To me, this shows that [Metro], historically speaking, has had a severe learning disability,” Robert L. Sumwalt, a member of the National Transportation Safety Board, said at a public hearing as the board finalized a report of its inquiry into the Jan. 12, 2015, smoke incident, which killed one train rider and sickened scores of others.

“Quite simply, they have not been willing to learn from prior events,” Sumwalt said. “Learning disabilities are tragic in children, but they are fatal in organizations. And literally that is true in this case.”

As for the calamitous chain of events on that rainy January afternoon — many details of which have become public in the past 16 months — the NTSB on Tuesday offered additional specifics and at least one big surprise:

The safety board said that Metro in the past (although not during the L’Enfant Plaza incident) routinely sent trains loaded with passengers into tunnels where smoke and fire had been reported so that train operators could investigate. Asked repeatedly about whether this has happened, a Metro spokeswoman did not answer directly, replying only that the transit agency has a policy against the practice.

According to the safety board, the January 2015 calamity unfolded this way:

An electrical malfunction involving defective power cables generated a mass of smoke on tunnel tracks just south of Metro’s L’Enfant Plaza station. A Pentagon-bound train encountered the smoke and stopped. Lacking sufficient electrical power — the power had been cut and the cables burned — the train could not back up.

Because of confusion among poorly trained controllers in Metro’s rail operations center and a lack of published guidelines, the crisis rapidly grew worse.

The controllers, at a command center in Landover, Md., botched the remote operation of ventilation fans in the tunnel, pushing the noxious fumes toward the train, not away from it. And because of Metro’s 15-minute delay in summoning firefighters, riders were stuck on the train for more than 35 minutes, gasping for air.

One of them, Carol I. Glover, 61, a grandmother from Alexandria, Va., was later pronounced dead of respiratory failure caused by smoke inhalation.

The NTSB also took a deep dive into Metro’s history, describing the L’Enfant Plaza crisis as a product of the transit agency’s decades-long record of shortcomings.

The report “reinforces obviously what I’ve been trying to do since day one, which is changing the culture,” said Metro General Manager Paul J. Wiedefeld, who took charge of the transit agency in late November. “We have to get infrastructure correct; we have to get the policies right; we have to get the people right.”

He said: “How has this gone on for 30 years? I think that’s the big takeaway here.”

The NTSB also faulted the District’s emergency response system, including the fire department and the Office of Unified Communications, which operates the 911 system.

And board members echoed their recommendation, first made last year, that Transportation Secretary Anthony Foxx urge Congress to shift responsibility for Metro safety oversight from the Federal Transit Administration to the Federal Railroad Administration, which the NTSB said has greater enforcement power.

They noted that trains hauling freight have more regulation than Metro, which carries hundreds of thousands of passengers a year.

Mark Jones, a veteran NTSB official who investigated the 2009 Red Line crash near Metro’s Fort Totten station that killed nine people, said he thought that calamity would lead to more regulation of U.S. subway systems.

“I thought Fort Totten would be a game changer,” Jones said. “. . . But there’s still no regulation, and as we sit here today, a coal train operating anywhere in this country has a lot more regulation than a Metro train does.”

NTSB Chairman Christopher A. Hart also had harsh words for the FTA, saying its efforts to oversee the safety of Metro’s rail system continue to fall short and noting that the agency had made recommendations that are “unenforceable.”

“WMATA needs a regulatory structure with rules, inspections and enforcement,” Hart said. “The FRA can provide all three.”

Foxx has declined to follow the recommendation, and his spokeswoman, Namrata Kolachalam, reacted sharply Tuesday to the renewed call for the change.

“One would think that [Foxx] could flip a switch and move safety oversight to the FRA,” she said in a statement. “We can’t. That’s the whole point we’ve been making. We find the NTSB’s continued fixation with FRA oversight confounding and counterproductive. Given the urgency of the safety issues with [Metro], is it better to draft legislation, send it to Congress, and hope they would act?”

As members of the Washington area’s congressional delegation reacted to the report, Rep. Gerald E. Connolly (D-Va.) also called for FRA oversight, saying that the NTSB report “once again clearly made the compelling case” for the proposed shift.

But Rep. Don Beyer (D-Va.) sided with Foxx. “My instinct is that Secretary Foxx made the decision to avoid internal battles, and I respect that,” Beyer said. “I think if it doesn’t work in six months, a year, we can always change that.”

The National Transportation Safety Board (NTSB) released on May 3 the results of its investigation of the January 2015 Yellow Line tunnel fire that killed one passenger and injured dozens more near the L’Enfant Plaza station. These are the key findings. (Claritza Jimenez/The Washington Post)

In faulting the District’s 911 emergency center, the NTSB said the center took four minutes and 19 seconds to process the first call for help about the smoke crisis — a far longer period than is optimal. And the fire department’s inadequate radio system in the subway hampered rescue efforts because firefighters were unable to efficiently communicate with one another, the NTSB said.

Michael Czin, a spokesman for D.C. Mayor Muriel E. Bowser (D), said that since the L’Enfant Plaza incident, “the District has taken decisive action and implemented common-sense reforms to strengthen the District’s emergency services and response.”

As for the initial 15-minute delay in calling 911, “Metro was unable to give us an explanation,” NTSB investigator Joe Gordon said at the hearing. He said the cause probably was “confusion” at the control center, where “the right hand didn’t know what the left hand was doing.”

The root cause of the calamity involved poorly maintained power cables and cable-connection assemblies on the tracks in the tunnel near L’Enfant Plaza, the NTSB said.

Trains are powered by electricity that flows along third rails. The electricity is delivered to the rails through thick, heavily insulated cables. If the insulation is worn or damaged, electricity can flow out, generating heat, fire and smoke. The phenomenon is called “arcing,” which is what the NTSB said caused the tunnel smoke.

As for why the train — No. 302 — was unable to back up, details on that became public recently in correspondence between the NTSB and Metro.

According to the documents, because some passengers on the train in the tunnel opened doors and got off — what officials call “self-evacuation” — train controllers cut power to the electrified third rail in the area, apparently for the safety of the self-evacuating passengers. As a result, the train was unable to return to the L’Enfant Plaza station.

Investigators think “the train could have moved if the action to move the train would have occurred in the very first few minutes,” accident investigator Michael Hiller said at Tuesday’s hearing. “But as time went on and cables burned and power became more degraded, that opportunity became less and less.”

Next came the control center’s remote operation of the tunnel vent fans, which was botched, according to the NTSB.

The safety board said Tuesday that the ventilation system near the L’Enfant Plaza station is old, of a kind designed in the 1960s and ’70s for station temperature control, not smoke removal. Metro knew from studies in the 1980s that the older vent systems were inadequate for smoke emergencies, the NTSB said. Yet the transit agency did not upgrade the systems, including the one near L’Enfant Plaza.

On Feb. 11, 2015, a month after the incident, the NTSB issued an emergency recommendation saying that Metro should draft detailed written procedures for activating its tunnel ventilation fans during a crisis such as the one on Jan. 12. The board said Metro had made matters worse that afternoon by turning on fans in an uncoordinated manner.

Specifically, the NTSB said then, the improper use of the fans caused a mass of smoke to move hundreds of feet toward the train while it was stuck in the tunnel. And the fumes lingered around the train as scores of riders gasped for air.

The problem was caused by Metro personnel in the Landover control center, the safety board said Tuesday. The train controllers activated two sets of giant fans at cross-purposes with devastating consequences, according to the board.

The two sets of fans, on opposite ends of the train, were both pulling the smoke instead of one set pushing while the other pulled, the NTSB said. As a result, the mass of fumes settled over the stationary train and stayed there.

If the fans had been properly coordinated, creating brisk air circulation, the smoke might have been expelled from the tunnel, the safety board said. The mistake occurred because the controllers lacked training and guidance, the board said.

Gordon, the NTSB investigator, said at the hearing, “They did not have a written procedure for how to respond.”

Said Sumwalt: “I think if I were to sum it up, whatever could go wrong that afternoon did go wrong. . . . To quote the title of a Shakespearean play, it was a comedy of errors. . . . Except for it was not funny.”

Robert McCartney, Michael Laris, Faiz Siddiqui and Luz Lazo contributed to this report.