United Airlines Flight 811

During the climb, the crew made preparations to divert around some thunderstorm activity along the aircraft's track, anticipated turbulence the captain kept the passenger seatbelt sign lit. As the plane was passing through 22,000 feet, the flight crew heard a loud "thump" which shook the aircraft.

A second and a half later, the forward cargo door blew off, swinging out with such force that it passed its normal stop and slammed into the side of the fuselage, bursting the fuselage open. Pressure differentials and aerodynamic forces caused the cabin floor to cave in, and ten seats (G and H of rows 8 through 12) were ejected from the cabin. All eight passengers seated in these locations were killed (seats 8G and 12G were unoccupied), as was the passenger in seat 9F.

A flight attendant was almost blown out of the aircraft. Thankfully passengers and crew members saw her clinging to a seat leg and were able to pull her back inside the cabin.

The crew immediately began an emergency descent, while performing a 180-degree back to Honolulu.

Debris ejected from the aircraft during the explosive decompression damaged the Number 3 and 4 engines. Engine 3 was experiencing heavy vibration, no N1 reading, and a low EGT and EPR, so the crew shut it down. At 02:20, an emergency was declared and the crew began dumping fuel to reduce the aircraft's landing weight. The N1 reading of engine number 4 continued to drop, with its EGT reading was high with visible flames, so they were forced to shut it down as well.

During the descent, Captain Cronin ordered Flight Engineer Thomas to tell the flight attendants to prepare for an emergency landing but was unable to contact them through the intercom. He asked the captain for permission to go down to find out what was happening, and Cronin agreed. When the Engineer opened the cockpit door he saw; the aircraft's skin was peeled off in some areas on the upper deck, revealing the frames and stringers and a massive hole in the side of the fuselage. Thomas returned to the cockpit and reported what he saw, wrongly concluding that it was probably a bomb.

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The crew, wary of the damage to their leading edges and additional drag of the stricken aircraft's gaping hole decided to land well over standard touchdown speeds. As the aircraft neared the airport, the gear was dropped, and partial flaps extended. Captain Cronin maintained 190–200 knots on the approach and touchdown, still managing to bring the plane to a halt, without overrunning the runway.

In all, 14 minutes had elapsed since the emergency was declared. All the remaining passengers and flight attendants exited the plane in less than 45 seconds.

Despite extensive air and sea searches, no remains were found at sea of the nine victims lost in flight.

Multiple small body fragments and pieces of clothing were found in the Number 3 engine, indicating that at least one victim ejected from the fuselage was ingested by the engine.

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In 1989 the flight crew received the Secretary's Award for Heroism for their actions. The aircraft was repaired, re-registered as N4724U in 1989, and returned to service with United Airlines in 1990.

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