Sixty-seven people are believed to have died after a passenger plane hit a military helicopter in mid-air near Washington DC's Ronald Reagan airport on Wednesday evening.

A deadly midair collision between an American Airlines jet and an Army helicopter near the nation's capital is bringing renewed focus on the federal agency charged with investigating aviation disasters.

By David Shepardson and Jeff Mason WASHINGTON (Reuters) -Crews worked to pull the remains of the U.S.' deadliest air disaster in two decades from Washington's Potomac River on Friday, searching for the cause of an incident that has raised questions about air safety and a shortage of tower controllers.