What we know about the American Airlines plane and Army helicopter crash over D.C.'s Potomac River
A regional jet carrying 64 people collided with an Army Black Hawk helicopter. Reagan National Airport grounded all flights.
Data from the deadliest U.S. air accident in a generation show conflicting altitude readings
Preliminary data from the deadliest U.S. aviation accident in nearly 25 years showed conflicting readings about the altitudes of an airliner and Army helicopter when they collided near Washington.