United Airlines Flight 811
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Incident
On February 24, 1989 United Airlines Flight 811, a Boeing 747-122 (registration number N4713U), experienced an explosive decompression as it was climbing between 22,000 and 23,000 feet after taking off from Honolulu International Airport, Hawaii, bound for Sydney, Australia, via Auckland, New Zealand with 3 flightcrew, 15 flight attendants, and 337 passengers aboard.
Upon decompression, nine passangers were ejected and lost at sea along with their seats, sections of the cabin flooring and other pieces of the aircraft's fuselage. Thirty other passengers received varying injuries, from bruises and cuts caused by flying debris, to minor frostbite due to the outside temperature freezing the passenger cabin after the explosion, to barotrauma, which afflicted most of the passengers near the fissure in the fuselage were seated. The remaining passengers and crew were uninjured, though shaken.
Cause
The decompression was caused by a combination of improper wiring in the R5 cargo door latching mechanism, and improper closing of that door by ground crew in Honolulu. At the time, the design of the 747-122 provided a small window situated flush against each of the cargo doors, so that the ground crew could visually confirm that the doors' latches were set to the locked position. There was, however, several flaws in this design. It didn't allow a particularly close look at the door latches, and it was also gunmetal gray, the same color as the latches. With these factors in place, an accident was bound to occur, and finally did on this flight. After the separation of the R5 door from the fuselage, it took a 15x3 foot section of the aircraft's skin with it, leaving the passenger cabin exposed to the elements at 22,000 feet. At this point the aircraft was approximately 20 miles from Honolulu, and managed to make a safe turnaround and a safe landing, after which an evacuation was immediately carried out.
Result
The NTSB issued an emergency recommendation [1] (http://www.ntsb.gov/publictn/1992/aar9202.htm) for all 747-122s in service at the time to replace their cargo door latching mechanisms. No similar accidents have occured on 747-122s since this accident.
The flight crew (none of whom were ejected during the explosion) received Congressional Medals of Honor for their actions later in 1989 [2] (http://www.uscg.mil/HQ/G-W/G-WP/G-WPM/g-wpm-3/MandAManual/ENCLOSURE%2019.pdf) (PDF). The aircraft was successfully repaired, re-registered as N4724U, and returned to service in 1990.
United Airlines ran a simulation through a flight simulator and were, despite many attempts and variable tweaks, unable to successfully land a plane after losing the R5 door.
External Links
- Passenger's Account of the Flight (http://www.airdisaster.com/eyewitness/ua811.shtml)
- Technical details of the incident (http://aviation-safety.net/database/record.php?id=19890224-0)
- Pre-incident photo of N4713U (http://images.airliners.net/open.file?id=543148&WxsIERv=Obrvat%20747-122&WdsYXMg=Havgrq%20Nveyvarf&QtODMg=Fna%20Qvrtb%20-%20Vagreangvbany%20%2F%20Yvaqoretu%20Svryq%20%28FNA%20%2F%20XFNA%29&ERDLTkt=HFN%20-%20Pnyvsbeavn&ktODMp=Wnahnel%201984&BP=0&WNEb25u=Senax%20P.%20Qhnegr%20We.&xsIERvdWdsY=A4713H&MgTUQtODMgKE=Frra%20ba%20ure%20gnxr-bss%20ebyy%2C%20ehajnl%2027.%20Ebhgvat%20FNA-UAY.%20Ba%20Sroehnel%2024%2C%201989%20fur%20ybfg%20ure%20sjq%20pnetb%20qbbe%20bire%20gur%20Cnpvsvp%20Bprna%20ba%20n%20syvtug%20sebz%20UAY.%20EE%20A4724H.&YXMgTUQtODMgKERD=2210&NEb25uZWxs=2004-03-28%2000%3A00%3A00&ODJ9dvCE=&O89Dcjdg=19875%2F89&static=yes&width=1254&height=812&sok=JURER%20%20%28ZNGPU%20%28nvepensg%2Cnveyvar%2Ccynpr%2Ccubgb_qngr%2Cpbhagel%2Cerznex%2Ccubgbtencure%2Crznvy%2Clrne%2Cert%2Cnvepensg_trarevp%2Cpa%2Cpbqr%29%20NTNVAFG%20%28%27%2B%22A4713H%22%27%20VA%20OBBYRNA%20ZBQR%29%29%20%20BEQRE%20OL%20cubgb_vq%20QRFP&photo_nr=2&prev_id=561804&next_id=108466)
- Post-incident/post-renumber photo of N4724U (http://images.airliners.net/open.file?id=062223&WxsIERv=Obrvat%20747-122&WdsYXMg=Havgrq%20Nveyvarf&QtODMg=Ybaqba%20-%20Urnguebj%20%28YUE%20%2F%20RTYY%29&ERDLTkt=HX%20-%20Ratynaq&ktODMp=Whyl%2010%2C%201993&BP=1&WNEb25u=Xbafgnagva%20iba%20Jrqryfgnrqg&xsIERvdWdsY=A4724H&MgTUQtODMgKE=Gur%20nvepensg%20gung%20evccrq%20bcra%20bire%20gur%20Cnpvsvp%20%28sbezreyl%20A4713H%29.&YXMgTUQtODMgKERD=1683&NEb25uZWxs=2000-01-13%2000%3A00%3A00&ODJ9dvCE=&O89Dcjdg=19875%2F89&static=yes&width=800&height=459&sok=JURER%20%20%28ZNGPU%20%28nvepensg%2Cnveyvar%2Ccynpr%2Ccubgb_qngr%2Cpbhagel%2Cerznex%2Ccubgbtencure%2Crznvy%2Clrne%2Cert%2Cnvepensg_trarevp%2Cpa%2Cpbqr%29%20NTNVAFG%20%28%27%2B%22A4713H%22%27%20VA%20OBBYRNA%20ZBQR%29%29%20%20BEQRE%20OL%20cubgb_vq%20QRFP&photo_nr=4&prev_id=108466&next_id=NEXTID)zh:聯合航空811號班機
