Efforts to retrieve the two aircraft involved in a crash in Washington DC that killed 67 people will be pushed forward on Friday as questions grow about air safety in the US capital.Divers have recovered the so-called black boxes from the American Airlines plane that crashed into the Potomac River after colliding with an Army Black Hawk helicopter on Wednesday.

Investigators plan to push forward on Friday with efforts to retrieve the two aircraft involved in a crash in Washington that killed 67 people and raised questions about air safety in the U.S. capital.