United Airlines Flight 811 was a regularly scheduled airline flight from Los Angeles to Sydney, with intermediate stops at Honolulu and Auckland. On February 24, 1989, the Boeing 747-122 serving the flight experienced a cargo-door failure in flight shortly after leaving Honolulu. The resulting explosive decompression blew out several rows of seats, killing nine passengers. The aircraft returned to Honolulu and landed with no further incident.
Aircraft
The aircraft involved was a Boeing 747-122 (registration number N4713U). It was delivered to United Airlines on November 3, 1970. It was the 89th 747 built. At the time of the accident, the Boeing had accumulated 58,814 total flight hours, 15,028 flight 'pressurization' cycles, and had not been involved in any previous accidents.
On February 24, 1989, the aircraft was scheduled by United Airlines to operate as Flight 811 from Los Angeles International Airport in Los Angeles, California, to Sydney Airport in Mascot, New South Wales, Australia, with intermediate stops at Honolulu International Airport in Honolulu, Hawaii, and Auckland Airport in Auckland, New Zealand. Flight 811 operated without incident on the first leg of the flight from Los Angeles to Honolulu and no difficulties were reported by the flight crew upon arriving at Honolulu, where a crew change occurred.
After the accident, the aircraft was repaired and put back into service with United, but was re-registered as N4724U. In 1997, the aircraft was taken out of service and passed onto Air Dabia as C5-FBS. Air Dabia ceased operations in 1998, and the aircraft was abandoned at Plattsburgh International Airport, where it was scrapped in 2004.
Flight crew
Starting in Honolulu, Flight 811 was under Captain David M. "Dave" Cronin (age 59). At the time of the accident, Cronin had logged around 28,000 flight hours, including roughly 1,600 hours in Boeing 747 aircraft. Flight 811 was Cronin's penultimate scheduled flight before his mandatory retirement.
The remaining flight crew consisted of First Officer Gregory Allen "Al" Slader (48), and Flight Engineer Randal Mark Thomas (46), and 15 flight attendants. The first officer and flight engineer had logged 14,500 flight hours and 20,000 flight hours, respectively.
Accident
Flight 811 took off from Honolulu International Airport at 01:52 local time, with 337 passengers and 18 crew members on board. During the climb, the crew made preparations to detour around thunderstorms along the plane's track; the captain anticipated turbulence and kept the passenger seatbelt sign lit.
The aircraft had been flying for 17 minutes, as it was passing from , when the flight crew heard a loud "thump", which shook the plane. About a second and a half later, the forward cargo door blew off. It swung out with such force that it tore a hole in the fuselage. Pressure differentials and aerodynamic forces caused the cabin floor to cave in, and 10 seats (G and H of rows 8 through 12) were ejected from the cabin. All eight passengers seated in these locations were ejected from the aircraft, as was the passenger in seat 9F. Seats 8G and 12G were unoccupied. A gaping hole was left in the aircraft, through which a flight attendant, Mae Sapolu in the business-class cabin, was almost blown out. Purser Laura Brentlinger hung on to the steps leading to the upper deck, and was dangling from them when the decompression occurred. Passengers and crew members saw her clinging to a seat leg and were able to pull her back inside the cabin, although she was severely injured.
The pilots initially believed that a bomb had gone off inside the airliner, as this accident happened just two months after Pan Am Flight 103 was blown up over Lockerbie, Scotland. They began an emergency descent to reach an altitude where the air was breathable, while also performing a 180° left turn to fly back to Honolulu. The explosion damaged components of the on-board emergency oxygen supply system, as it was primarily located in the forward cargo sidewall area, just aft of the cargo door.