All aircraft flying near Ronald Reagan National Airport will now be required to broadcast their positions to air traffic controllers, the acting administrator of the Federal Aviation Administration told a Senate subcommittee on Thursday.

The policy, which took effect on Thursday, was put in place after it was revealed that technology in an Army helicopter that collided with a passenger jet near the airport in January was turned off at the time of the deadly crash.

Known as the Automatic Dependent Surveillance-Broadcast Out, the technology broadcasts an aircraft’s position, altitude and speed, and it could have allowed air traffic controllers to better track the helicopter’s movements. Military helicopters can turn off the technology during so-called continuity of government missions, which take place during national emergencies and ensure that the whereabouts of top government officials remain untracked.

The policy change was disclosed as the F.A.A. and military officials were pressed by senators to explain how the Army helicopter, which was on a training mission, could have collided with the passenger jet, which was coming in to land on a heavily trafficked route.

“The fact of the matter is, we have to do better,” Chris Rocheleau, the acting F.A.A. administrator, said on Thursday. “We have to identify trends, we have to get smarter on how we use data and when we put corrective actions in place. We must implement them with diligence.”

Mr. Rocheleau said there would be some exemptions to the new policy, though those were not discussed during the hearing. He appeared before Senate panel with Jennifer Homendy, the chairwoman of the National Transportation Safety Board, and Brig. Gen. Matt Braman, the Army’s director of aviation. For about two hours, they answered questions about the ongoing investigation into the January crash, which killed 67 people.

It was the first investigative hearing into collision by the subcommittee, the aviation panel of the Senate Commerce, Science and Transportation Committee. Senator Ted Cruz, a Texas Republican who chairs the Transportation Committee, said that military and other operations had continued to interfere with passenger flights at Reagan Airport. He cited an example on March 1 when several commercial planes landing at the airport reported alerts of nearby aircraft, in some cases paired with automated instructions to take urgent action to avoid a crash.

The warnings were apparently caused by the Secret Service and the Navy “improperly testing counter-drone technology,” Mr. Cruz said, which caused radio interference with a vital system that commercial planes use to prevent midair collisions.

“Let me just say this is deeply disturbing that just a month after 67 people died while on approach to DCA that the Secret Service and Pentagon would inadvertently cause multiple flights to receive urgent cockpit alerts recommending evasive action,” Mr. Cruz said, using the initials designating the airport, which is in Virginia, across the Potomac River from downtown Washington.

Senators Jerry Moran, a Kansas Republican who chairs the aviation subcommittee, and Maria Cantwell, Democrat of Washington, questioned Mr. Rocheleau about why the F.A.A. had missed warning signs regarding the potential for collisions between military helicopters and commercial airplanes at Reagan Airport.

A preliminary report by the N.T.S.B. found that a helicopter and a commercial plane nearly collided at least once a month near Reagan from 2011 to 2024, raising concerns about how the F.A.A. had overlooked such a hazard at one of the nation’s busiest airports.

Ms. Homendy and Sean Duffy, the transportation secretary, criticized the F.A.A. for not recognizing the frequency of near-misses at the airport and addressing the issues.

In response, Mr. Rocheleau acknowledged that the agency had missed crucial signs.

“I will continue to review what I mentioned before with respect to the hot spots,” Mr. Rocheleau said, “working closely with N.T.S.B. to learn what happened here and to make sure it never happens again.”