WASHINGTON (NEXSTAR) — Lawmakers received a closed-door briefing from federal investigators regarding last week’s fatal mid-air collision between an American Airlines jet and a U.S. Army Black Hawk helicopter near Ronald Reagan Washington National Airport.

The crash resulted in the deaths of all 67 individuals on board both aircraft.

Sen. Ted Cruz (R-Texas) says he learned that the helicopter’s Automatic Dependent Surveillance-Broadcast (ADS-B) system—a critical safety feature for tracking aircraft—was turned off during the training mission, despite no compelling national security reason for its deactivation.

Following the collision, the Federal Aviation Administration (FAA) restricted helicopter flights near Reagan National Airport and limited the volume of air traffic into the facility. These measures aim to enhance safety protocols in the congested airspace surrounding the airport.

Sen. Andy Kim (D-N.J.) says he’s concerned about the protocols governing the crowded airspace. 

“My concern is about the actual aircraft. In terms of the protocols in such a crowded airspace,” Kim said. 

Sen. Shelley Moore Capito (R-W.Va.) believes investigators are committed to determining the cause of the accident and implementing corrective measures to prevent future crashes.

“I could tell people that we are going to know what happened,” Capito said. “We’re going to be able to make corrections so that doesn’t happen again.”

The crash has also exposed issues with the nation’s air traffic control systems. Sen. Cruz criticized the current technology as outdated.

“Our air traffic control technology is from the 1950s. We are literally using radar and strips of paper and floppy disks,” Cruz said.

Sen. Jerry Moran (R-Kan.) says it’s necessary to invest in modernization efforts to ensure the highest levels of air travel safety.  

“We must be willing to spend the money necessary to make air travel absolutely as safe as it can be,” Moran said. 

President Donald Trump has called on federal investigators to thoroughly examine the incident and has advocated for improvements to the air traffic control system.

The National Transportation Safety Board (NTSB) continues to investigate the collision, preliminary data appears to indicate that the helicopter was flying above the permitted altitude for its route.