The NTSB is set to hold a hearing on the DCA midair collision. Here's what to know

On Feb. 3, a crane removes airplane wreckage from the Potomac River, where American Airlines Flight 5342 collided with a U.S. Army Black Hawk helicopter near Ronald Reagan Washington National Airport in Virginia. All 67 people aboard both aircraft died in the collision as the jet was attempting to land. Roberto Schmidt/AFP via Getty Images hide caption

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Roberto Schmidt/AFP via Getty Images

WASHINGTON — It has been six months since an American Airlines regional jet and a U.S. Army Black Hawk helicopter collided in midair near Washington, D.C., killing all 67 people on board both aircraft.

The crash has been under investigation by the National Transportation Safety Board, which is set to begin a three-day investigative hearing this week to share new information on the deadliest U.S. aviation accident in decades.

The January air disaster renewed concerns about U.S. aviation safety and raised questions about the crowded airspace around the nation's capital, which is shared by commercial, military and government aircraft.

Here's what you need to know ahead of the NTSB hearing starting Wednesday.

It's the deadliest U.S. aviation accident since 2001

The Jan. 29 crash occurred as the PSA Airlines flight out of Wichita, Kan., was approaching Ronald Reagan Washington National Airport (DCA) in Arlington, Va., for landing. Two pilots, two flight attendants and 60 passengers were on board the American Airlines regional jet.

Around the same time, an Army helicopter was tracing a path south along the Potomac River on a training mission. It had a three-person crew.

The plane and the helicopter collided at about 8:48 p.m. local time, sending both aircraft into the frigid river below. It was the deadliest U.S. aviation incident since 2001.

DCA airspace was known to be a problem

The aviation industry has long warned about the congested airspace around DCA.

NTSB Chairwoman Jennifer Homendy said in March that flight patterns around the airport just outside Washington, D.C., had created an "an intolerable risk." She noted that an NTSB analysis had found at least one "close call" per month between a helicopter and a commercial plane flying through DCA from 2011 to 2024.

This year the NTSB recommended — and U.S. Transportation Secretary Sean Duffy accepted — two new policies in light of the crash: permanently restricting nonessential helicopter operations around DCA and eliminating mixed helicopter and fixed-wing traffic.

Were the Black Hawk altimeters not working properly?

Investigators said the instruments telling the helicopter pilots how high they were flying — the altimeters — may not have been functioning as intended.

A radio altitude reading showed that the crash took place at 278 feet, but the helicopter shouldn't have been flying above 200 feet.

Homendy said that the Black Hawk crew may have been seeing a different reading inside the helicopter and that NTSB investigators were finding "conflicting information in the data."

There are other factors before the collision that the NTSB is examining. The board found that at least one radio transmission from DCA air traffic control may have been "stepped on" and not heard by the helicopter's crew.

Investigators also noted that the three helicopter crew members were likely wearing night-vision goggles throughout the flight, which could have affected their ability to see everything around them.

The hearing is about fact-finding, not assigning blame

The goal of NTSB investigative hearings, such as the one beginning this week, is to help the board obtain "information necessary to determine the facts and circumstances" of an accident.

Topics on the agenda include the helicopter's data systems, the complicated DCA airspace and training and guidance given to DCA air traffic controllers.

Though the NTSB board members may determine the probable cause of the crash, the board won't assign blame for the collision. It will instead offer a series of recommendations and proposals to the Federal Aviation Administration to try to prevent a similar crash from happening again.

The NTSB's full investigative report is expected to be complete early next year.