It’s been one week since American Eagle Flight 5342 crashed into the Potomac River, and the work has only begun to recover from the deadliest U.S.

Pilots and flight attendants are aware of risks, but commercial aviation tragedies have been infrequent in the U.S. for years.

The communication team at American Airlines had to activate a crisis plan it hoped it would never have to use after last week's midair collision of a passenger jet and Army helicopter that claimed 67 lives.

The deadliest plane crash in U.S. history was in May 1979, when American Airlines Flight 191 lost an engine during takeoff at Chicago O’Hare International Airport and crashed moments later, killing 258 passengers and 13 crew. Two people on the ground also were killed.