Crew erroneously reported bomb onboard to tower after hearing explosion. Radar tracked door down to ocean contact. Nine passengers were ejected and lost at sea. The aircraft was a Boeing 747-122, an early 747 with high flight time and flight cycles. Boeing 747-122 series high flight time aircraft are prone to cargo door malfunctions.
Doors pop open in climb or just after.
Door popping open exposes large hole in side of nose. Large hole in side of nose can tear nose off depending of variables such as angle of attack, airspeed, turbulence and strength of fuselage. Cargo door would be picked up as radar return as it spun away from aircraft. Door opened inadvertently because of various reasons consistent with other confirmed, documented, and witnessed cargo door openings such as design error, improper latching, electrical problems, wear and tear, or other unknown reason. Pan Am Flight 103 was a scheduled passenger flight from London to New York.