On April 1, 1956, a Martin 4-0-4, registration #N40403, operating as TWA Flight 400, crashed on takeoff from Greater Pittsburgh International Airport (PIT). Twenty-two of the 36 people aboard the aircraft, including one crewmember, perished in the evening crash on Easter Sunday.

The Martin 4-0-4 was an American pressurized passenger airliner built by the Glenn L. Martin Company. In addition to airline use initially in the United States, it was used by the United States Coast Guard and United States Navy as the RM-1G.