Key senators and the families of the 67 people who died when an airliner and Army helicopter collided near Washington, D.C., are convinced advanced aircraft locator systems that experts have been recommending for decades would have prevented the crash.

The National Transportation Safety Board says the placement of a helicopter route so close to Reagan National Airport's secondary runway was a key factor in causing a midair aircraft collision that killed 67 people near Washington, D.C., a year ago.

So many things went wrong last Jan. 29 to contribute to the collision between an airliner and a U.S. Army helicopter that killed 67 people that the National Transportation Safety Board isn’t likely to identify a single cause at its hearing Tuesday.