The Army Black Hawk helicopter involved in the fatal midair collision in Washington, D.C., had a tracking system turned off, Sen. Ted Cruz said.

A key safety system was turned off in a US army helicopter when it crashed into an American Airlines flight last week, killing 67 people.

Now, the U.S. Army Corps of Engineers will focus on retrieving the mangled helicopter, a crucial component in federal authorities' probe as they look to confirm data related to its altitude at the time of the collision,