Thai Airways International Flight 311
Encyclopedia
Thai Airways International
Flight 311 was a flight from Bangkok
, Thailand
's Don Mueang International Airport to Kathmandu, Nepal
's Tribhuvan International Airport
. On 31 July 1992, an A310-304
on the route, registration HS-TID, crash
ed on approach to Tribhuvan. All 113 on board were killed.
Flight 311 departed Don Mueang at 10:30 AM local time. After crossing into Nepalese airspace the pilots contacted air traffic control
and were cleared to an instrument approach
from the south called the "Sierra VOR
Circling Approach" for Runway 20. Nepalese ATC at the time was not equipped with radar.
Shortly after reporting the Sierra fix ten miles south of the Kathmandu VOR, the aircraft called ATC asking for a diversion to Calcutta, India
because of a "technical problem"; before ATC could reply, the flight rescinded their previous transmission. The flight was then cleared for a straight-in Sierra approach to Runway 02 and told to report leaving 9,500 feet. The captain asked numerous times for the winds and visibility at the airport but ATC merely told him that Runway 02 was available.
A number of frustrating and misleading communications (due partly to language problems and partly to the inexperience of the air traffic controller, who was a trainee with only nine months on the job) ensued between air traffic control and the pilots regarding Flight 311's altitude and distance from the airport. The captain asked four times for permission to turn left, but after receiving no firm reply to his requests he announced that he was turning right and climbed the aircraft to flight level 200. The controller handling Flight 311 assumed from the flight's transmissions that the aircraft had called off the approach and was turning to the south, and he therefore cleared the aircraft to 11,500 feet, an altitude that would have been safe in the area south of the airport. The flight descended back to 11,500 feet, went through a 360 degree turn, passed over the airport northbound, and crashed on a steep rock face in a remote area of the Langtang
National Park at an altitude of 11,500 feet.
Investigators from the Nepalese aviation authority, Airbus Industrie, and the Transportation Safety Board of Canada
(which assisted with technical details) determined that the aircraft had experienced a minor fault in the workings of the inboard trailing flap
s just after the aircraft reached the Sierra reporting fix. Concerned that the complex approach into Kathmandu in instrument conditions
would be difficult with malfunctioning flaps and frustrated by ATC and his first officer's inconclusive and weak answers to his questions, the captain decided to divert to Calcutta. The flaps suddenly began to work properly, but the captain was forced to resolve more aspects of the difficult approach himself due to his first officer's lack of initiative. Only after numerous extremely frustrating exchanges with ATC was the captain able to obtain adequate weather information for the airport, but by that time he had overflown Kathmandu and the aircraft was headed towards the Himalayas.
The Nepalese authorities found that the probable causes of the accident were the captain's and controller's loss of situational awareness; language and technical problems causing the captain to experience frustration and a high workload; the first officer's lack of initiative and inconclusive answers to the captain's questions; the air traffic controller's inexperience, poor grasp of English, and reluctance to interfere with what he saw as piloting matters such as terrain separation; poor supervision of the inexperienced air traffic controller; Thai Airways International's failure to provide simulator training for the complex Kathmandu approach to its pilots; and improper use of the aircraft's flight management system.
This accident took place on the same date that China General Aviation Flight 7552
crashed out of control at Nanjing
, People's Republic of China
, killing 108 out of 126, and only 59 days before PIA Flight 268
crashed just south of Kathmandu, killing 167.
The remains of the aircraft can still be seen in Langtang National Park
, and have been featured in Lonely Planet
guidebooks as a point of interest on the trek from Ghopte to the Tharepati Pass.
The flight number since the accident has been re-numbered to 319 for the outbound flight and 320 for the flight back to Bangkok, using a Boeing 777
.
Thai Airways International
Thai Airways International Public Company Limited is the national flag carrier and largest airline of Thailand. Formed in 1988, the airline's headquarters are located in Chatuchak District, Bangkok, and operates out of Suvarnabhumi Airport. Thai is a founding member of the Star Alliance. Thai is a...
Flight 311 was a flight from Bangkok
Bangkok
Bangkok is the capital and largest urban area city in Thailand. It is known in Thai as Krung Thep Maha Nakhon or simply Krung Thep , meaning "city of angels." The full name of Bangkok is Krung Thep Mahanakhon Amon Rattanakosin Mahintharayutthaya Mahadilok Phop Noppharat Ratchathani Burirom...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
's Don Mueang International Airport to Kathmandu, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
's Tribhuvan International Airport
Tribhuvan International Airport
Tribhuvan International Airport is an international airport situated in Kathmandu, Nepal.Tribhuvan is the sole international airport in Nepal. There are two terminals, one domestic and one international...
. On 31 July 1992, an A310-304
Airbus A310
The Airbus A310 is a medium- to long-range twin-engine widebody jet airliner. Launched in July 1978, it was the second aircraft created by Airbus Industrie,a consortium of European aerospace companies, Airbus is now fully owned by EADS and since 2001 has been known as Airbus SAS. the consortium of...
on the route, registration HS-TID, crash
Aviation accidents and incidents
An aviation accident is defined in the Convention on International Civil Aviation Annex 13 as an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, in which a...
ed on approach to Tribhuvan. All 113 on board were killed.
Flight 311 departed Don Mueang at 10:30 AM local time. After crossing into Nepalese airspace the pilots contacted air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
and were cleared to an instrument approach
Instrument approach
For aircraft operating under instrument flight rules , an instrument approach or instrument approach procedure is a series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing, or to a point...
from the south called the "Sierra VOR
VHF omnidirectional range
VOR, short for VHF omnidirectional radio range, is a type of radio navigation system for aircraft. A VOR ground station broadcasts a VHF radio composite signal including the station's identifier, voice , and navigation signal. The identifier is typically a two- or three-letter string in Morse code...
Circling Approach" for Runway 20. Nepalese ATC at the time was not equipped with radar.
Shortly after reporting the Sierra fix ten miles south of the Kathmandu VOR, the aircraft called ATC asking for a diversion to Calcutta, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
because of a "technical problem"; before ATC could reply, the flight rescinded their previous transmission. The flight was then cleared for a straight-in Sierra approach to Runway 02 and told to report leaving 9,500 feet. The captain asked numerous times for the winds and visibility at the airport but ATC merely told him that Runway 02 was available.
A number of frustrating and misleading communications (due partly to language problems and partly to the inexperience of the air traffic controller, who was a trainee with only nine months on the job) ensued between air traffic control and the pilots regarding Flight 311's altitude and distance from the airport. The captain asked four times for permission to turn left, but after receiving no firm reply to his requests he announced that he was turning right and climbed the aircraft to flight level 200. The controller handling Flight 311 assumed from the flight's transmissions that the aircraft had called off the approach and was turning to the south, and he therefore cleared the aircraft to 11,500 feet, an altitude that would have been safe in the area south of the airport. The flight descended back to 11,500 feet, went through a 360 degree turn, passed over the airport northbound, and crashed on a steep rock face in a remote area of the Langtang
Langtang
Langtang is a region in Nepal to the north of Kathmandu and bordering Tibet. It is protected as Langtang National Park and has a number of high peaks including Langtang Lirung . As of 2010, the entrance ticket to the park cost 2400 Nepali Rupees for foreigners.About 4,500 people live inside the...
National Park at an altitude of 11,500 feet.
Investigators from the Nepalese aviation authority, Airbus Industrie, and the Transportation Safety Board of Canada
Transportation Safety Board of Canada
The Transportation Safety Board of Canada , officially the Canadian Transportation Accident Investigation and Safety Board is the agency of the Government of Canada responsible for maintaining...
(which assisted with technical details) determined that the aircraft had experienced a minor fault in the workings of the inboard trailing flap
Flap (aircraft)
Flaps are normally hinged surfaces mounted on the trailing edges of the wings of a fixed-wing aircraft to reduce the speed an aircraft can be safely flown at and to increase the angle of descent for landing without increasing air speed. They shorten takeoff and landing distances as well as...
s just after the aircraft reached the Sierra reporting fix. Concerned that the complex approach into Kathmandu in instrument conditions
Instrument flight rules
Instrument flight rules are one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other are visual flight rules ....
would be difficult with malfunctioning flaps and frustrated by ATC and his first officer's inconclusive and weak answers to his questions, the captain decided to divert to Calcutta. The flaps suddenly began to work properly, but the captain was forced to resolve more aspects of the difficult approach himself due to his first officer's lack of initiative. Only after numerous extremely frustrating exchanges with ATC was the captain able to obtain adequate weather information for the airport, but by that time he had overflown Kathmandu and the aircraft was headed towards the Himalayas.
The Nepalese authorities found that the probable causes of the accident were the captain's and controller's loss of situational awareness; language and technical problems causing the captain to experience frustration and a high workload; the first officer's lack of initiative and inconclusive answers to the captain's questions; the air traffic controller's inexperience, poor grasp of English, and reluctance to interfere with what he saw as piloting matters such as terrain separation; poor supervision of the inexperienced air traffic controller; Thai Airways International's failure to provide simulator training for the complex Kathmandu approach to its pilots; and improper use of the aircraft's flight management system.
This accident took place on the same date that China General Aviation Flight 7552
China General Aviation Flight 7552
China General Aviation Flight 7552 was a China General Aviation flight from Nanjing Airport, Nanjing to Xiamen Airport, Xiamen. On July 31, 1992, the Yakovlev 42D on the route crashed into a pond past the runway after taking off. 8 of the 10 crew members and 100 of the 116 passengers died....
crashed out of control at Nanjing
Nanjing
' is the capital of Jiangsu province in China and has a prominent place in Chinese history and culture, having been the capital of China on several occasions...
, People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
, killing 108 out of 126, and only 59 days before PIA Flight 268
PIA Flight 268
Pakistan International Airlines Flight 268 was an Airbus A300B4-203, registration AP-BCP, which crashed on approach to Kathmandu's Tribhuvan International Airport on 28 September 1992. All 167 on board were killed....
crashed just south of Kathmandu, killing 167.
The remains of the aircraft can still be seen in Langtang National Park
Langtang National Park
Langtang National Park is the fourth national park in Nepal and was established in 1976 as the first Himalayan national park. The protected area exceeds an altitudinal range of and covers an area of in the Nuwakot, Rasuwa and Sindhulpalchok districts of the central Himalayan region encompassing...
, and have been featured in Lonely Planet
Lonely Planet
Lonely Planet is the largest travel guide book and digital media publisher in the world. The company is owned by BBC Worldwide, which bought a 75% share from the founders Maureen and Tony Wheeler in 2007 and the final 25% in February 2011...
guidebooks as a point of interest on the trek from Ghopte to the Tharepati Pass.
The flight number since the accident has been re-numbered to 319 for the outbound flight and 320 for the flight back to Bangkok, using a Boeing 777
Boeing 777
The Boeing 777 is a long-range, wide-body twin-engine jet airliner manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and is commonly referred to as the "Triple Seven". The aircraft has seating for over 300 passengers and has a range from , depending on model...
.
See also
- Lists of accidents and incidents on commercial airliners
- Air safetyAir safetyAir safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.-United...
- Controlled flight into terrainControlled flight into terrainControlled flight into terrain describes an accident in which an airworthy aircraft, under pilot control, is unintentionally flown into the ground, a mountain, water, or an obstacle. The term was coined by engineers at Boeing in the late 1970s...