Army Black Hawk helicopter in DC crash was practicing disaster drill

Three Army soldiers, one pilot and two crew members, were killed when their helicopter crashed into a passenger airplane near Washington were practicing a plan to evacuate senior leaders in the event of a catastrophic disaster or serious threat to the U.S. government.

In the wake of the Wednesday night collision of the Army Black Hawk helicopter with the American Airlines jet as it prepared to land in Ronald Reagan Washington National Airport, questions were raised about why the helicopter was rounding a busy air traffic area at night.

After hours of searching through the frigid waters of the Potomac River for survivors, officials announced that all the people in the crash – 64 people aboard the passenger plane and three crew members on the helicopter – were killed.

Secretary of Defense Pete Hegseth later revealed the three crewmembers aboard the UH-60 helicopter were on a "routine annual retraining" carrying night-vision goggles on board.

The military has said it won't know until an investigation headed by the National Transportation Safety Board is completed why the crash happened. Here's what we know about the training mission that led to the deadly crash.

Pilots were rehearsing plans for catastrophic emergency

The training flight falls under the Army's "continuity of government" plans – procedures for how the military would respond to a catastrophic government emergency or threat to national security.

The crewmembers on board were training with the 12th Aviation Battalion, which fulfills a "special mission" in the Washington, D.C., region, Jonathan Koziol, chief of staff of the Army's aviation directorate, told reporters on Thursday.

More: Army helicopter in DC crash was on 'routine' training flight carrying night-goggles

In the event of a disaster serious enough to put continuity of government plans into motion, the brigade would also swoop in to evacuate leaders to a safe location. The battalion runs training flights around the area, like the one the downed Black Hawk was on, to give pilots practice navigating the environment, air traffic and planned evacuation routes, Koziol said.

The Army runs the training flights "on a near daily basis," around the clock, Koziol said. "These are flown every day by multiple aircraft," he said.

Questions raised about night-vision goggles on board

Hegseth described the training flight as a required "night evaluation," adding that the pilots had night-vision goggles on board.

The Army has said it couldn't reveal whether the crew members were wearing the goggles at the time of the crash. But the goggles wouldn't be necessary, according to Koziol. In a bright environment like the Washington area, the pilots would have easily been able to tell where they were.

"In my experience from 30 years of flying, that would be an easy route to fly unaided" by the goggles, he said.

Continuity of government created during Cold War

Continuity of government plans were first formed during the Cold War, as fear that Russia would launch a direct strike on the U.S. gripped the country.

After the second tower of the World Trade Center fell on 9/11, President George W. Bush activated for the first time a temporary "shadow government" to maintain of control of government, according to an online White House information page. As part of those plans, each agency has designated representatives that join an "emergency relocation group" that travel to other locations on a rotating basis.

This article originally appeared on USA TODAY: Army helicopter in DC crash was training national catastrophe plans