Lauda Air Flight 004

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Lauda Air Flight 004
Lauda Air Boeing 767 OE-LAV called Mozart.jpg
OE-LAV, the Lauda Air Boeing 767-300ER aircraft involved in the accident
Accident summary
Date 26 May 1991
Summary In-flight breakup caused by uncommanded thrust reverser deployment
Site Phu Toei National Park,
Amphoe Dan Chang, Suphanburi Province, Thailand
Passengers 213
Crew 10
Fatalities 223 (all)
Survivors 0
Aircraft type Boeing 767-3Z9ER
Aircraft name Mozart
Operator Lauda Air
Registration OE-LAV
Flight origin Kai Tak Airport, Hong Kong
Last stopover Don Mueang International Airport,
Bangkok, Thailand
Destination Vienna International Airport,
Vienna, Austria

Lauda Air Flight 004 was a regularly-scheduled international passenger flight between Bangkok, Thailand and Vienna, Austria. On 26 May 1991 a Boeing 767-300ER operating the flight crashed due to an uncommanded deployment of the thrust reverser on the No.1 engine in mid-flight, killing all 213 passengers and the ten crew members on board. It is the deadliest aviation accident involving a Boeing 767 and the deadliest aviation accident in Thailand. The crash also marked the aircraft type's first fatal incident and first hull loss.[1] Lauda Air was founded and run by the former Formula One world motor racing champion Niki Lauda. Lauda was personally involved in the accident investigation.


The aircraft involved was a Boeing 767-300ER that had been delivered new to Lauda Air on 16 October 1989.[2] It wore the manufacturing number MSN 24628, was registered as OE-LAV, and was christened Mozart.[citation needed]

History of the flight[edit]

At the time of the accident, Lauda Air operated three weekly flights between Bangkok and Vienna.[1] On 26 May 1991, at 23:02 local time, flight NG004 (originating from Hong Kong's Kai Tak Airport), a Boeing 767-3Z9ER, took off from Old Bangkok International Airport for its flight to Vienna International Airport with 213 passengers and ten crew, under the command of Captain Thomas J. Welch of the United States and First Officer Josef Thurner of Austria.[citation needed]

At 23:08, Welch and Thurner received a visual warning indicating that a possible system failure would cause the thrust reverser on the number one engine to deploy in flight. Having consulted the aircraft's quick reference handbook, they determined that it was "just an advisory thing" and took no action.[3]

At 23:17, the thrust reverser on the number one engine deployed while the plane was over mountainous jungle terrain in the border area between Suphanburi and Uthai Thani provinces in Thailand. Thurner's last recorded words were, "Oh, reverser's deployed".[4][5] The lift on the aircraft's left side was disrupted due to the reverser deployment, and the aircraft was placed in an immediate diving left turn. The aircraft went into a diving speed of Mach 0.99, and may have broken the sound barrier. The aircraft broke up in mid-air at 4,000 feet (1,200 m).[6] Most of the wreckage was scattered over a remote forest area roughly 1 km2 in size, at an elevation of 600 m (2,000 ft) above sea level, in what is now Phu Toei National Park, Suphanburi. The wreckage site is about 6 kilometres (3 nmi) north-northeast of Phu Toey, Huay Kamin, Dan Chang District, Suphan Buri Province,[7] about 160 kilometres (100 mi) northwest of Bangkok, close to the Burma-Thailand border.[1][8]

None of the 223 passengers and crew aboard the airliner survived. Rescuers found Welch's body still in the pilot's seat.[9]


Volunteer rescue teams and local villagers looted the wreckage, taking electronics and jewellery,[10] so relatives were unable to recover personal possessions. The bodies were taken to a hospital in Bangkok. The storage was not refrigerated and the bodies decomposed. Dental and forensic experts worked to identify bodies, but twenty-seven were never identified.[11]


Speculation that a bomb may have destroyed the aircraft circulated. The Philadelphia Inquirer, citing wire services it did not identify, stated that, "the search for a motive is difficult because politically neutral Austria has generally stayed out of most international conflicts – such as the Persian Gulf war – that have made other countries' airlines the targets of terrorist attacks."[12] According to a security officer working at an embassy of a Western country, a Lauda Air employee stationed in Bangkok had threatened to use a bomb to destroy a Lauda aircraft unless he was given money.[citation needed] Lauda Air fired the employee, but he was later hired by Thai Airways International, which handled luggage loading and uploading for Lauda Air in Bangkok. Niki Lauda, owner of the airline, said that the airline never received a threat.[12]


Niki Lauda (pictured here in 1996) traveled to Thailand to personally investigate the crash

The flight data recorder was damaged to the point of being unreadable, so only the cockpit voice recorder was of use. Pradit Hoprasatsuk, the head of the Air Safety Division of the Thailand Department of Aviation, stated, "the attempt to determine why the reverser came on was hampered by the loss of the flight data recorder, which was destroyed in the crash".[13] Upon hearing of the crash, Niki Lauda traveled to Thailand. He examined the wreckage and estimated that the largest fragment was about 5 metres (16 ft) by 2 metres (6.6 ft), which was about half the size of the largest piece in the Lockerbie crash.[14] In Thailand, Lauda attended a funeral for 23 unidentified passengers, and then traveled to Seattle to meet with Boeing representatives.

The official investigation took about eight months.[15] It did not determine the cause of the thrust reverser deployment. Different possibilities were investigated, including a short circuit in the system. Due in part to the destruction of much of the wiring, no definitive reason for the activation of the thrust reverser could be found.[7]

As evidence started to point towards the thrust reversers as the cause of the accident, simulator flights were made at Gatwick Airport which appeared to show that deployment of a thrust reverser was a survivable incident. Lauda said that the thrust reverser could not be the sole cause of the crash.[16] The accident report states that the "flightcrew training simulators yielded erroneous results"[17] and stated that recovery from the loss of lift from the reverser deployment "was uncontrollable for an unexpecting flight crew".[18] The incident led Boeing to modify the thrust reverser system to prevent similar occurrences by adding sync-locks, which prevent the thrust reversers from deploying when the main landing gear truck tilt angle is not at the ground position.[7][19]

The aviation writer Macarthur Job has said that "had that Boeing 767 been of an earlier version of the type, fitted with engines that were controlled mechanically rather than electronically, then that accident could not have happened".[4]

Niki Lauda's visit with Boeing[edit]

Lauda said, "what really annoyed me was Boeing's reaction once the cause was clear. Boeing did not want to say anything."[15] Lauda asked Boeing to fly the scenario in a simulator. Boeing initially refused, but Lauda insisted. Lauda attempted the flight in the simulator 15 times, and in every instance he was unable to recover. He asked Boeing to issue a statement, but the legal department said it could not be issued because it would take three months to adjust the wording. Lauda asked for a press conference the following day, and told Boeing that if it was possible to recover, he would be willing to fly on a 767 with two pilots and have the thrust reverser deploy in air. Boeing told Lauda that it was not possible, so he asked Boeing to issue a statement saying that it would not be survivable, and Boeing issued the statement. Lauda said, "this was the first time in eight months that it had been made clear that the manufacturer was at fault and not the operator of the aeroplane."[15]

Previous testing of thrust reversers[edit]

When the Federal Aviation Administration (FAA) of the United States asked Boeing to do tests activating the thrust reverser in flight,[20] the FAA had allowed Boeing to establish the tests of the thrust reverser. Boeing had insisted that a deployment was not possible in flight. In 1982 Boeing established a test where the aircraft was slowed to 250 knots, and the test pilots then used the thrust reverser. The control of the aircraft had not been jeopardized. The FAA accepted the results of the test.[21]

The Lauda aircraft was traveling at a high speed when the thrust reversers deployed, causing the pilots to lose control of the aircraft. James R. Chiles, author of Inviting Disaster, said, "the point here is not that a thorough test would have told the pilots Thomas J. Welch and Josef Thumer [sic] what to do. A thrust reverser deploying in flight might not have been survivable, anyway. But a thorough test would have informed the FAA and Boeing that thrust reversers deploying in midair was such a dangerous occurrence that Boeing needed to install a positive lock that would prevent such an event." As a result of their findings during the investigation process of Lauda Flight 004, additional safety features such as mechanical positive locks were mandated to prevent thrust reverser deployment in flight.[22]

Passengers and crew[edit]

Nationality Passengers Crew Total
Austria Austria 74 9 83
Australia Australia 1 0 1
Brazil Brazil 1 0 1
China China 6 0 6
Germany Germany 4 0 4
Hong Kong Hong Kong 52 0 52
Hungary Hungary 2 0 2
Italy Italy 10 0 10
Philippines Philippines 2 0 2
Poland Poland 1 0 1
Portugal Portugal 3 0 3
Switzerland Switzerland 7 0 7
Taiwan Taiwan 3 0 3
Thailand Thailand 39 0 39
Turkey Turkey 1 0 1
United Kingdom United Kingdom 2 0 2
United States United States 2 1 3
Socialist Federal Republic of Yugoslavia Yugoslavia 3 0 3
Total 213 10 223

The passengers and crew included 83 Austrians:[23] 74 Austrian passengers and nine Austrian crew members.[24] 52 Hong Kong residents were on board the aircraft.[24][25] Other nationalities included Thais (39), Italians (10), Swiss (7), Chinese (6), Germans (4), Portuguese (3), Taiwanese (3), Yugoslavs (3), Hungarians (2), Filipinos (2), Britons (2), Americans (2), Australian (1), Brazilian (1), Polish (1), and Turkish (1).[24] In addition, an American was the aircraft's pilot.[26]

Of the passengers, 125 had boarded in Hong Kong, while the rest boarded in Bangkok.[23] Of the passengers who boarded in Bangkok, there were 38 Thais, 34 Austrians, seven Swiss, four Germans, two Yugoslavs, one Australian, one Briton, and one Hungarian.[1] Of the passengers who boarded in Hong Kong, most were either Austrian or Chinese.[8]

Of the passengers, 10 were from South Tyrol in Italy. Six of them were students of the University of Innsbruck School of Economics, and they originated from Val Gardena (Gröden), Kiens (Chienes), Klausen (Chiusa), Mals (Malles Venosta), and Olang (Valdaora). The other four were from Bolzano (Bozen), including two public officers, a musician, and his daughter. The musician was traveling with his Chinese wife.[27]

Notable victims[edit]

  • Donald McIntosh, a 43-year-old British senior United Nations anti-drug official posted in Bangkok. His death caused Austrian newspapers to post initial speculation stating that people bombed the airplane to kill him; a UN spokesperson said that he was not on a secret mission and could not have been a target of an assassination.[9][23]
  • Pairat Decharin, the Governor of Chiang Mai Province, and his wife.[9][28] Charles S. Ahlgren, the former U.S. consul general to Chiang Mai, said "That accident not only took their lives and that of many of Chiang Mai's leaders, but dealt a blow to many development and planning activities in the town."[29]
  • Clemens August Andreae, an Austrian economics professor,[30] was leading a group of students from the University of Innsbruck on a tour of the Far East.[27]
  • Mom Sinuan Na Chiangmai (หม่อมศรีนวล ณ เชียงใหม่), the consort of Chao Ratchabut (Wongtawan Na Chiang Mai), the Prince of Chiang Mai[31]
  • Winit Winitchaiyaphak (วินิจ วินิจฉัยภาค), the deputy principal private secretary[32]
  • Chao Phongkaeo Na Lamphun (เจ้าพงศ์แก้ว ณ ลำพูน), the daughter of Chao Ratchabut.[31]

Josef Thurner, the copilot, once flew as a copilot with Niki Lauda on a Lauda Boeing 767 service to Bangkok, a flight that was the subject of a Reader's Digest article in January 1990 that depicted the airline positively. Macarthur Job said that, as a result, Thurner was the better known of the crew members.[33] Thomas J. Welch, the captain, lived in Vienna,[24] but originated from Seattle, Washington.[26]


Lauda Air Flight 004 memorial

About one quarter of the airline's carrying capacity was destroyed as a result of the crash.[34] Following the crash of OE-LAV, the airline had no flights to Sydney, on 1, 6, and 7 June. Flights resumed with another 767 on 13 June.[35] Niki Lauda said that the crash in 1991 and the period after was the worst time in his life.[15] After the crash, bookings from Hong Kong decreased by 20% but additional passengers from Vienna began booking flights, so there were no significant changes in overall bookings.[25]

In early August 1991, Boeing issued an alert to airlines stating that over 1,600 late model 737s, 757s, 767s, and 747s had thrust-reverser systems similar to that of the OE-LAV. On Monday, 9 September 1991, the Boeing Commercial Airplane Group asked its customers to replace a valve in the thrust reverser systems that could cause the thrust reverser to deploy in flight.[36]

Fourteen months before 25 May 1993, Boeing and Lauda Air came to a joint settlement with most of the families of the deceased victims, but by 25 May 1993, 20 families that had children as claimants had not yet received settlement money. The law firm Sinclair Roche represented almost all of the relatives of the Hong Kong residents who died in the crash.[citation needed]

At the crash site, which is accessible to national park visitors, a shrine was later erected to commemorate the victims.[37] Another memorial and cemetery is located at Wat Sa Kaeo Srisanpetch – GPS location: 14°29′32″N 100°00′07″E / 14.492145°N 100.001884°E / 14.492145; 100.001884, some 90 km away in Amphoe Mueang Suphanburi.[38]

Television episodes[edit]


Location of crash site; departure, stopover, and destination airports
Hong Kong
Hong Kong
Crash site
Crash site
Location of departure, stopover, crash site and destination
Location of stopover and crash site
Don Mueang Airport
Don Mueang Airport
Crash site
Crash site
Location of stopover and crash site

See also[edit]


  1. ^ a b c d Tummachartvijit, Tavorn. "Cause of airliner explosion Sought". Associated Press at The Dispatch. Monday 27 May 1991. 1A and 6A.
  2. ^ – Boeing 767 – MSN 24628 – OE-LAV retrieved 3 July 2016
  3. ^ Accident description at the Aviation Safety Network
  4. ^ a b Job, Macarthur (1996). Air Disaster Volume 2, Aerospace Publications, ISBN 1-875671-19-6: pp.203–217
  5. ^ "Accident Report, Appendix A, page 55". Archived from the original on 27 May 2011. Retrieved 14 February 2014. 
  6. ^ Chiles, p. 309.
  7. ^ a b c "Accident Report". Archived from the original on 27 May 2011. Retrieved 14 February 2014. 
  8. ^ a b "More Than 200 Believed Killed As Plane Crashes in Thai Jungle". Associated Press. 27 May 1991. Retrieved on 27 January 2013.
  9. ^ a b c "UN drug man 'not Thai bomb target'". The Independent. Thursday 30 May 1991. Available on LexisNexis.
  10. ^ Johnson, Sharen Shaw. "Scavengers complicate crash probe". USA Today. 29 May 1991. News 4A.
  11. ^ Finlay, Victoria. "Relatives return to crash site for memorial service". South China Morning Post. Tuesday 25 May 1993. Retrieved on 26 May 2013.
  12. ^ a b "Looting May Hurt Jet-crash Probe; Airline Chief Denies Extortion Plot". Inquirer Wire Services at The Philadelphia Inquirer. 1. Retrieved on 26 May 2013.
  13. ^ Archive. Associated Press. 31 August 1993. Retrieved on 16 March 2014.
  14. ^ "Looting may have hidden clues to crash". The Advertiser. Thursday 30 May 1991.
  15. ^ a b c d Lauda, Niki (interview by Maurice Hamilton). "Niki Lauda: 'People had lost their loved ones yet no one was telling them why'". Observer Sport Monthly at The Guardian. 29 October 2006. Retrieved on 15 February 2013.
  16. ^ "Rejects Thrust as Cause of Air Crash". The New York Times. 7 June 1991. Retrieved on 26 January 2013.
  17. ^ "Accident Report, section 2.3, page 21". Archived from the original on 27 May 2011. Retrieved 14 February 2014. 
  18. ^ "Accident Report, section 3.1, 9, page 41". Archived from the original on 27 May 2011. Retrieved 14 February 2014. 
  19. ^ Acohido, Byron. "Boeing Thrust Reversers Had History Of Glitches". Chicago Tribune. 
  20. ^ Chiles, p. 112-113
  21. ^ Chiles, p. 113
  22. ^ Chiles, p. 114.
  23. ^ a b c Traynor, Irian, Nick Cumming-Bruce, and Steve Vines. "Crash teams investigate plane blast". The Independent. 28 May 1991. Available on LexisNexis.
  24. ^ a b c d Wallace, Charles P. "'All Evidence' in Thai Air Crash Points to Bomb". Los Angeles Times. 28 May 1991. 2. Retrieved on 15 February 2013.
  25. ^ a b Finlay, Victoria. "Jet tragedy families wait on pay". South China Morning Post. Tuesday 25 May 1993. Retrieved on 27 January 2013.
  26. ^ a b "Pilots' Final Words". Associated Press at The Seattle Times. Thursday 6 June 1991. Retrieved on 15 February 2013.
  27. ^ a b Parschalk and Thaler, p. 394 "Sechs der zehn Südtiroler Opfer sind Studenten der Innsbrucker Fakultät für Wirtschaftswissenschaften aus Klausen, Gröden, Olang, Mals und Kiens, die unter der Leitung von Clemens August Andreae an einer Exkursion nach Fernost teilgenommen hatten. Die anderen vier Südtiroler Todesopfer – alle aus Bozen – sind zwei Beamte sowie ein Berufsmusiker mit seiner chinesischen Frau und dem in Bozen geborenen Töchterchen der beiden."
  28. ^ "รายนามผู้ดำรงตำแหน่งผู้ว่าราชการจังหวัดเชียงใหม่". (in Thai). Retrieved March 17, 2017. 
  29. ^ "Special Messages from 8 U.S. Consuls General in Chiang Mai". (Archive) Department of State. Retrieved on 15 February 2013. Thai version, Archive
  30. ^ "Lauda Air-Absturz in Thailand jährt sich zum 20. Mal." Die Presse. 26 May 2011. Retrieved on 14 February 2013. "Das Unglück 1991 in Thailand war das dritte schwere, von dem ein österreichisches Verkehrsflugzeug betroffen war. Am 26. September 1960 hatte der Absturz einer "Vickers-Viscount"-Turboprop-Maschine der AUA beim Landeanflug auf den Moskauer Flughafen Scheremetjewo 31 Tote gefordert. Schuld war damals eine falsche Höhenmesser-Einstellung. Am 23. September 1989 war eine mit elf Personen besetzte "Commander AC 90" der Rheintal-Flug beim Landeanflug auf den Flughafen Altenrhein am schweizerischen Ufer des Bodensees bei dichtem Nebel in das Gewässer gestürzt. Dabei kam auch der damalige Sozialminister Alfred Dallinger (S) ums Leben." and "In Thailand starb der Innsbrucker Wirtschaftswissenschafter Univ.-Prof. Clemens August Andreae."
  31. ^ a b "คอลัมน์: ผ่อ...เมืองเหนือ: อดีต ผู้ว่าฯ ไพรัตน์ เดชะรินทร์" [Column: Looking at the Northern Cities: Pairat Decharin, former governor]. Naew Na. 17 February 2009. Archived from the original on 15 February 2013. Retrieved 16 February 2013.  () "ข้อมูลนี้ผิดผู้ที่สร้างกำแพงเมืองและประตูเมืองขึ้นมาใหม่คือคุณชัยยา พูนศิริวงศ์ คนที่นั่งเครื่องบินเลาด้าแอร์ไลน์ตกตายหมู่คือคุณไพรัตน์ เดชะรินทร์ พร้อมคุณนาย ก็ต้องให้ความเป็นธรรมกับผู้ตายและคณะที่ตายพร้อมกับผู้ว่าฯไพรัตน์ เป็นคุณหญิงสองท่านคือ หม่อมศรีนวล ณ เชียงใหม่ ชายาเจ้าราชบุตร (วงค์ตะวัน) ณ เชียงใหม่ สายตรงพระเจ้ากาวิละ และเจ้าพงษ์แก้ว ณ ลำพูน ลูกสาวเจ้าราชบุตร นอกนั้นอีก 10 กว่าคนเป็นคหบดีชื่อดังของเชียงใหม่ทั้งสิ้น ทุกคนที่เสียชีวิต ล้วนแต่เป็นนักสังคมสงเคราะห์ช่วยเหลือประชาชนที่ยากไร้มานานไม่ต่ำกว่าคนละ 20 ขึ้นไป"
  32. ^ "โศกนาฏกรรมนกเหล็ก จากอดีตถึงวันนี้" [Tragedies of the iron birds: From the past to the present]. Manager. 5 August 2009. Archived from the original on 15 February 2013. Retrieved 16 February 2013.  () "26 พฤษภาคม 2534 (สุพรรณบุรี) หากถามว่า เหตุการณ์เครื่องบินตกครั้งไหนรุนแรงและสยองขวัญที่สุดในเมืองไทย เชื่อว่าคงไม่หนีไม่พ้นอุบัติเหตุเครื่องบินของเลาด้าแอร์ตกอย่างแน่นอน เพราะในครั้งนั้นได้คร่าชีวิตผู้โดยสารไปถึง 223 คน โดยเป็นคนไทยจำนวน 39 คน ซึ่งหลายคนก็มีชื่อเสียง อย่างนายวินิจ วินิจฉัยภาค รองราชเลขาธิการ นายไพรัตน์ เดชะรินทร์ ผู้ว่าราชการจังหวัดเชียงใหม่ ฯลฯ"
  33. ^ Job, p. 204. "Of all the crew, Josef Thurner was perhaps the better known thanks to having been copilot to Niki Lauda himself on a Boeing 737 service to Bangkok which became the subject of a highly affirmative article on the airline and its history in the January 1990 issue of The Reader's Digest[...]"
  34. ^ Traynor, Ian. "Lauda's driving ambition brings triumph and disaster in tandem". The Independent. 28 May 1991.
  35. ^ Aircraft, Volume 71. p. 44. "LAUDA AIR/LDA: Following the still unexplained loss of B767-329ER OE-LAV [24628] Mozart, there were no flights to Sydney by the Austrian carrier on 1, 6 and 7 June. Services resumed on 13 June with B767-3T9 (ER) OE-LAU [23765 xN6009F]
  36. ^ Lane, Polly and Byron Acohido. "Boeing Tells 757 Owners To Replace Part – Faulty Thrust-Reverser Valve Blamed In 767 Accident That Killed 223". Seattle Times. Monday, 9 September 1991. Retrieved on 15 February 2013.
  37. ^ Paknam Web – Phu Toei National Park Archived 8 December 2010 at the Wayback Machine.
  38. ^ Paknam Web – Lauda Air Cemetery
  39. ^ ข่าวดังข้ามเวลา : เลาด้า...คืนฟ้าโศก (23 มี.ค.58)


Further reading[edit]

External links[edit]

Coordinates: 14°57′N 99°27′E / 14.950°N 99.450°E / 14.950; 99.450