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Thai Airways International Flight 311

From Alfawiki
Thai Airways International
Company typeAirline
IndustryAviation
Headquarters
Bangkok
,
Thailand
Area served
International
ProductsAir transport services

Thai Airways International Flight 311 (TG311/THA311) operated a route from Don Mueang International Airport in Bangkok, Thailand to Tribhuvan International Airport in Kathmandu, Nepal. On July 31, 1992, at 07:00:26 UTC (12:45:26 NST; 14:00:26 ICT), the Airbus A310-304 assigned to this flight collided with a mountain located north of Kathmandu, resulting in the deaths of all 113 passengers and crew members aboard. This incident represented the first fatal crash and total loss of an Airbus A310 aircraft.

Aircraft

The aircraft involved was an Airbus A310-304, produced by Airbus Industrie in 1987, bearing registration HS-TID and serial number 438. It was equipped with two General Electric CF6-80C2A2 turbofan engines.

Crew

Having been in commercial operation for five years, the plane was piloted by Captain Preeda Suttimai, aged 41, who had accumulated 13,200 flight hours, including 4,400 hours on the A310 and 1,700 hours as Pilot In Command. First Officer Phunthat Boonyayej, aged 52, possessed 14,600 total flight hours with 4,200 on this aircraft type. The cabin was staffed by twelve attendants attending to 99 passengers.

Accident

Flight 311 took off from Bangkok at 10:30 local time (UTC+7) or 03:30 UTC, with an expected arrival in Kathmandu at 12:55 NST (07:10 UTC). Upon entering Nepalese airspace, the crew contacted air traffic control (ATC) and received clearance for the "Sierra VOR circling approach" to Runway 20. At that time, Nepalese ATC did not have radar capabilities.

Shortly after reporting reaching the Sierra fix, the pilots requested diversion to Calcutta due to a "technical problem," but later withdrew this request. They were then authorized for a straight-in Sierra approach to Runway 02 and instructed to report upon leaving the fix. Despite several inquiries about wind and visibility conditions, ATC only confirmed that Runway 02 was operational.

The captain made multiple attempts to obtain permission for a left turn but received no definitive answer; he then announced a right turn and climbed to flight level 200. The controller interpreted this as an aborted approach with a southbound turn and cleared the aircraft to descend to a safe altitude south of the airport. The plane descended to 11,500 feet, executed a full 360° turn, and passed over the airport heading north.

Just moments before impact, the ground proximity warning system (GPWS) sounded an alert warning of impending terrain collision. First Officer Boonyayej urged Captain Suttimai to initiate a turn; however, Suttimai dismissed these alerts as false warnings. The aircraft ultimately crashed into a steep cliff within Langtang National Park at an altitude of approximately , traveling at about ground speed. All occupants perished.

Investigation

The investigation team comprised officials from the Civil Aviation Authority of Nepal, representatives from Airbus Industrie, and members of the Transportation Safety Board of Canada. They discovered a minor malfunction in the inboard trailing flaps shortly after passing the Sierra reporting fix. Faced with the challenging instrument approach into Kathmandu and frustrated by unclear communications from both ATC and his first officer, the captain initially opted to divert to Calcutta. Once flap function was restored, he assumed primary control over most aspects of the demanding approach due to his first officer’s lack of assertiveness. Delayed acquisition of sufficient weather information led to the aircraft overshooting Kathmandu and proceeding toward mountainous terrain.

Nepalese investigators attributed probable causes to factors including loss of situational awareness by both captain and ATC; language barriers and technical difficulties that increased workload; passivity on the part of the first officer; inexperienced ATC personnel with limited English proficiency who hesitated to intervene for terrain separation; inadequate ATC supervision; Thai Airways International’s omission of simulator training tailored for Kathmandu’s complex approach; and improper utilization of the flight management system.

During field investigations en route to the crash site, senior Airbus test pilot Gordon Corps (62), who had logged more than 11,500 flight hours, succumbed to altitude sickness.

Victims

Nationality Passengers Crew Total
Australia 1 0 1
Belgium 5 0 5
Canada 2 0 2
Finland 5 0 5
Germany 4 0 4
Israel 2 0 2
Japan 17 0 17
Nepal 23 0 23
New Zealand 1 0 1
South Korea 2 0 2
Spain 3 0 3
Thailand 21 14 35
United Kingdom 2 0 2
United States 11 0 11
Total (14 Nationalities) 99 14 113

Prominent casualties

Aftermath

Following the tragedy, Thai Airways discontinued the use of flight numbers 311 and 312, substituting them with 319 and 320. These routes operated with Airbus A310 aircraft until they were succeeded by Boeing 777 models in 2001. Remnants of the wreckage can still be seen within Langtang National Park along the trekking path from Ghopte to Tharepati Pass.

Just fifty-nine days afterward, Pakistan International Airlines Flight 268 crashed near Kathmandu, resulting in the deaths of all 167 passengers and crew onboard—marking the deadliest aviation disaster in Pakistan’s history.

Dramatization

This incident is depicted in Season 17, Episode 10 of Mayday (also known as Air Crash Investigation), under the title "The Lost Plane".

See also

Notes


External links

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