Senators are seeking to change the bill that would allow the military to operate as it did before the D.C. plane crash

Senators from both parties on Thursday pushed for changes to a massive defense bill after plane crash investigators and victims’ families warned that the legislation would undo key safety reforms stemming from a collision between a plane and a military helicopter over Washington, D.C., that killed 67 people.

The head of the National Transportation Safety Board, which is investigating the crash, a group of victims’ family members and senators on the Commerce Committee, said the bill introduced by the House on Wednesday would make America’s skies less safe. They added that this would allow the military to operate in the same way as it did before the plane crash last January, which was the deadliest in more than two decades.

He watches: NTSB finds Army helicopter crashed in midair with plane above altitude limit

Democratic Sen. Maria Cantwell and Republican committee chairman Sen. Ted Cruz introduced two amendments Thursday to repeal the troubling helicopter safety provisions and replace them with a bill they introduced last summer to strengthen the requirements, but it’s not clear whether Republican leadership would allow the National Defense Authorization Act to be changed at this point because that would delay its passage.

“We owe it to families to put actual safety improvements into law, and not give the Department of Defense even bigger loopholes to exploit,” the senators said.

The bill would undo the reforms

For now, the bill includes exceptions that would allow military helicopters to fly through the crowded airspace around the nation’s capital without using a key system called ADS-B to broadcast their positions just as they did before the January collision. The FAA began requiring this in March. NTSB Chairwoman Jennifer Homendy called the bill a “major safety setback” that calls for a repeat of that disaster.

“It poses an unacceptable risk to air travelers, to commercial and military aircraft and their crews, and to the residents of the area,” Homendy said. “It is also an unimaginable exclusion of our investigation and of the 67 families… who lost loved ones in a tragedy that could have been completely prevented. This is shameful.”

The largest unions representing pilots, flight attendants and other transportation workers joined the chorus criticizing the bill on Thursday. Sarah Nelson, president of the Association of Flight Attendants, asked why this was suggested. These rulings are “not only reckless and indefensible, but also a direct undermining of the National Transportation Safety Board’s safety guidance,” she said.

Congress may resort to another bill to address these concerns

Senate Majority Leader John Thune said he is looking into the concerns but believes they can be addressed by passing an aviation safety bill proposed by Cruz and Cantwell last summer that would require all aircraft operators to use both forms of ADS-B, or Automatic Dependent Surveillance Broadcast, the technology to broadcast aircraft location data to other aircraft and air traffic controllers. Most aircraft today are equipped with ADS-B Out equipment but airlines are having to add more comprehensive ADS-B In technology to their aircraft.

This legislation would also eliminate the exemption for ADS-B transmission requests for Department of Defense aircraft.

“I think this would resolve people’s concerns about this provision, and hopefully we’ll see if we can find a way forward to get this bill done,” said Thune, a Republican from South Dakota.

The Army routinely flew without the ADS-B system operational

The military used national security waivers before the accident to circumvent FAA safety requirements on the grounds that they were concerned about security risks from revealing the locations of their helicopters. This bill only adds “a window-dressing fix that would continue to allow requirements to be set aside without anything more than a cursory risk assessment,” said Tim and Sherry Lilly, whose son Sam was the first officer on an American Airlines plane.

Military helicopters like the Black Hawk involved in the crash sent some position data to controllers through a transponder, but the FAA said ADS-B data is more accurate, and the NTSB has recommended for decades that all aircraft be equipped with such systems. The Army was concerned about using these systems because anyone—including aircraft enthusiasts on the ground—could use them to know precisely where a helicopter or plane was.

Homendy said it would be silly to task the military with assessing safety risks when they are not experts, and neither the Army nor the Federal Aviation Administration observed 85 close calls around Ronald Reagan Washington National Airport in the years leading up to the accident. The Army doesn’t know how to do that kind of risk assessment, she said, adding that no one writing the bill bothered to consult experts at the NTSB who did.

The NTSB’s final report on the cause of the D.C. crash won’t be released until next year, but investigators have already determined a number of contributing factors, including that the helicopter was flying too high on a route that provided little separation between helicopters and planes landing on Reagan’s secondary runway.

Part of the investigation focuses on limitations on various systems designed to alert other pilots and air traffic controllers about the plane’s location, Homendy said. The pilots of the American plane, which was flying to the capital from Wichita, Kansas, received a warning about nearby traffic 20 seconds before the collision. But at a low altitude, the plane was flying as it prepared to land, and the basic collision avoidance system recommended by the bill was suppressed in part to prevent false alarms and because there was little room to maneuver.

The White House and the Army did not immediately respond Thursday to questions about these safety concerns in the bill. But earlier this week, Trump made clear that he wanted to sign the National Defense Authorization Act because it advances a number of his priorities and provides a 3.8% pay raise for many military personnel.

The Senate is expected to consider the bill next week, and it seems unlikely that any final changes will be made. But Congress is leaving for the weekend, and the defense bill is considered a must-pass by the end of the year.