DC plane crash live updates: Investigators comb through wreckage for clues

The pilots of the U.S. Army Black Hawk helicopter that collided with the regional American Airlines jet last week, were believed to be wearing night vision goggles at the time of the crash, an official said.

“We do believe, given the mission and given what we’ve heard or not heard on the [cockpit voice recorder] that they were wearing night vision goggles,” National Transportation Safety Board Chair Jennifer Homendy said during a press gaggle Thursday.

She said that's according to NTSB's preliminary information.

Homendy also said the NTSB did not know for sure that the Automatic Dependent Surveillance-Broadcast (ADS-B) tracking system was installed on the helicopter and the agency is awaiting further evaluation.

Earlier, Sen. Ted Cruz, of Texas, said lawmakers were briefed by the Federal Aviation Administration and told that the data from the ADS-B system in the helicopter was "turned off."

-ABC News' Ayesha Ali and Clara McMichael

Pieces of the downed Black Hawk helicopter were removed from the Potomac River on Thursday as the investigation into the cause of the crash continues.

The Federal Aviation Administration has notified airlines that it is "about to announce a slightly lower rate for" Reagan airport.

"Due to the two offload runways being closed, we are running a 28 arrival rate which is the maximum number in a peak operation for a single runway," the FAA said, according to an email obtained by ABC News.

This action is being taken as the FAA and National Transportation Safety Board investigators expressed concerns for the tower personnel on duty due to "an increased level of stress while also having a front row view of the accident recovery," the email said.

"We believe easing up on the gas a bit, and reducing from a 28 to a 26 rate, will reduce risk and allow a little space for extra coordination," the FAA said in the email.

-ABC News' Ayesha Ali

Sen. Maria Cantwell, D-Wash., wrote a letter to Transportation Secretary Sean Duffy, saying that involving Elon Musk in the Federal Aviation Administration’s safety system or process is a "conflict of interest."

"FAA has the legal responsibility for safety oversight of companies with commercial space transportation licenses," Cantwell wrote.

"Elon Musk’s SpaceX rocket launches share the airspace with commercial airplanes, and the FAA has the responsibility for keeping the entire airspace safe. SpaceX has been fined by the FAA for failing to comply with specific requirements in its launch license," Cantwell said. "Mr. Musk, in turn, called for the firing of Mike Whitaker, the FAA Administrator who the Senate confirmed 98-0 because the FAA issued a fine against SpaceX for not following the rules. We have ethics and recusal laws for a reason -- to prevent corporate interference in protecting the public interest."

-ABC News’ Clara McMichael