Air crash investigations can take months, and federal investigators told reporters they would not speculate on the cause.
Officials also heavily restricted helicopter traffic around the airport, an official said ... a range of factors in what National Transportation Safety Board Chairwoman Jennifer Homendy has ...
Police boats combed the banks of the Potomac River on Friday, slowly scanning the shoreline in the rain as investigators sought clues into the midair collision that killed 67 people and raised ...