Diving crews are still searching the icy waters of the Potomac River looking to retrieve the bodies of all the people killed in this week’s plane and helicopter collision. Retired Black Hawk instructor pilot Martin Gottholm discusses the difficulties in flying at night for Black Hawk pilots and questions surrounding the altitudes of the aircrafts at the time.

The military helicopter that collided with an American Airlines flight this week was conducting training to prepare for a catastrophe or attack on the US.