The deadly mid-air collision over Washington, D.C., has reignited concerns over air traffic congestion and safety risks at Ronald Reagan Washington National Airport, a tightly packed aviation hub that shares airspace with military and government flights.

The National Transportation Safety Board said it was too soon to speculate the cause of the deadly crash. Skaters, parents, and coaches from the Skating Club of Boston were aboard the flight.

In the three years before the deadly collision between an Army helicopter and an American Airlines flight near Reagan National Airport, at least two other pilots reported near-misses with helicopters while landing at the airport,

In the aftermath of the midair collision between an American Airlines plane and a U.S. Army Black Hawk helicopter on Wednesday, Jan. 29, the Federal Aviation Administration is indefinitely restricting helicopter flights in the vicinity of Washington,

The FAA has indefinitely closed routes near Reagan National Airport to most helicopter traffic after the deadly collision.