Two separate plane crashes in Washington, D.C., and Philadelphia occurred as one tragic crash in California reached its 25th anniversary.

Everyone aboard a plane that collided with an Army helicopter near Washington, D.C., are feared dead, which would make it the deadliest U.S. air crash in nearly 24 years.

Conflicting reports have emerged on the cause of the plane crash in Washington, D.C. last week. An American Airlines jet collided with a U.S. Army Black Hawk helicopter outside of Ronald Reagan National Airport in Washington,