Why aircraft collision avoidance technology may not have helped prevent D.C. mid-air crash [Video]

As the investigation begins into the cause of the mid-air crash between an American Airlines regional passenger jet and a U.S. army Black Hawk helicopter, questions have been raised about the role played by the Traffic Alert and Collision Avoidance System (TCAS).

The collision, which occurred as the jet approached Ronald Reagan Washington National Airport near Washington, D.C, sent both aircraft into the Potomac River. Everyone aboard both aircraft, which included 60 passengers and four crew on the plane, and three soldiers on the helicopter, were killed.

However TCAS technology is supposed to be an effective tool in helping prevent such accidents. Here’s what we know about the system and what it could have done in this situation.

How does TCAS work?

Problems with mid-air …