A timeline of the tragic collision between a commercial plane and a Black Hawk helicopter over the Potomac River, with insights into the ongoing investigation.

Retired Delta pilot Mark Stephens says there are two airports on the East Coast that he considers particularly dangerous: LaGuardia and Reagan.

Washington’s National Airport has one of the most congested airspaces in the United States, with as many as 800 landings and departures daily, along with military and government helicopters constantly ...