Hundreds of families are in mourning after an American Airlines regional jet collided with a U.S. Army Black Hawk helicopter on Jan. 29, with both aircraft plunging into the Potomac River near Ronald Reagan Washington National Airport in Washington, D.C. No one survived.

After American Airlines Flight 5342 and a U.S. Army helicopter collided mid-air, officials shared insight into the respective pilots’ communication with air traffic control.

LIVE: Watch the NTSB press conference in the video player above. The collision was the deadliest plane crash in the U.S. since 2001, when a jet slammed into a New York City neighborhood just after takeoff,