|Qantas B747-438 VH-OJH (image embedded from [http://upload.wikimedia.org/wikipedia/commons/thumb/2/23/Qantas_Boeing_747-400%2C_VH-OJH%2C_SIN_for_web.jpg/250px-Qantas_Boeing_747-400%2C_VH-OJH%2C_SIN_for_web.jpg] on 17 August 2009)|
On October 23, 1999, a Boeing 747-400 passenger aircraft with the Australian aircraft registration of VH-OJH had a runway overrun during landing at Bangkok Don Mueang International Airport. At 2245hours Bangkok Local time (1545 UTC), Flight QF001 operated by Qantas, overran Runway 21L while executing a landing under torrential downpour and poor visibility conditions. QF001 was making a scheduled stopover in Bangkok, Thailand for its service between Sydney and London. There is no fatalities. 38 people sustained minor injuries.
1) Deficient Flight Training & Procedures
Qantas’ Boeing 747-400 Standard Operating Procedures (SOP) encouraged its flight crew to execute landings with wings flaps lowered at 25 degrees and using no reverse thrust. This policy was implemented for cost saving, noise abatement, brake wear reduction and a quieter passenger landing experience.
The SOP did not indicate that it is mandatory for the flight crew to lower the flaps down to the maximum 30 degrees. By setting the wing flaps at the maximum 30 degrees, the aircraft is able to land at the slowest safest airspeed and thereby uses minimum runway landing distance. The aircraft flaps were instead lowered to a mere 25 degrees.
The SOP also did not indicate that it is compulsory for the flight crew to use full reverse thrust during landing, especially when landing on a water-affected wet airstrip during rainy weather conditions. Full reverse thrust is more effective in slowing the aircraft down on a wet runway as hydroplaning and skidding may occur with the application of landing gears brakes.
The SOP advised the flight crew to lower the wing flaps to the maximum 30 degrees and apply full reverse thrust if their airmanship judgment deemed them necessary to do so, such as during inclement weather. However they did not choose to do so. This reflected inadequacy in the flight crew training and knowledge in evaluating the possibility of a wet/contaminated runway and selecting the appropriate landing configuration during torrential rain conditions.
The flight crew members were trained according to the deficient SOP.
2) Ungrooved Runway Surface
The Don Mueang airport management did not instill grooved surface for their runways, thereby decreasing flight operational safety when the runways were wet. QF001 hydroplaned and skidded as a result.
1) Failing to Establish a Stable Final Approach
QF1 entered the final approach with a high altitude and airspeed. Runway 21L has a non-standard glide scope of 3.15 degrees. Ironically, the altitude and airspeed that QF001 was maintaining were within Qantas’ SOP limits.
2) Poor Crew Resource Management (CRM) (Confusion of Actions)
The Pilot-In-Command (PIC) for the landing was the First Officer. As the area visibility had reduced to 750 metres at the time of the landing, the Captain instructed the First Officer to execute a go-around due to the absence of the runway in sight as well as the long touchdown runway zone. The First Officer immediately pushed the throttles forward into the Take Off/ Go Around (TO/GA) engine power configuration. However, upon noticing the improvement of visibility and that the main landing gears have successfully touched down on the runway, the Captain retarded the thrust levers. As the Captain was not the PIC, he should not have done so. In addition, his intentions were not conveyed at all to the First Officer. This led to the subsequent confusion between the instructed input of the First Officer by the Captain and the sudden abrupt actions of the Captain.
3) Poor Decision Making
The Captain should have been assertive in his intentions to execute a go-around. By being indecisive at the final crucial moment, he also unintentionally failed to idle all four engines, leaving one engine running at the TO/GA power configuration. This could be due to a stressful high workload and dedication of all his focus on the remaining length of the runway as the aircraft failed to decelerate effectively. In fact, this action caused the aircraft to accelerate for a couple of seconds after the main gears have touched down firmly on the runway.
As a result of his delayed decision, the aircraft landed too far down the runway.
The preselected auto-brake was also cancelled automatically due to one engine running at the TO/GA power configuration. The flight crew only realized the absence of braking and applied manual braking when the aircraft was more than 1600 metres from the start of Runway 21L.
1) All airline operators should ensure that their flight crews are sufficiently trained and knowledgeable for operating their aircraft on wet/contaminated runways.
2) All airline operators should be adequately trained in collecting and analyzing the necessary information calmly and effectively during emergencies before executing the most suitable actions.
3) Airline flight crew training should emphasize the importance of CRM training in ensuring that flight crew maintain effective communication, leadership and decision making at all times during flight operations.
4) All civilian aerodromes should assign budgetary priorities to upgrading facilities that ensure safe flight operations at all times. Runways should be grooved to reduce the possibility of aircraft hydroplaning, skidding or drifting during wet/contaminated runway conditions.
Australian Transport Safety Bureau. (1999, September 23). Investigation Report 199904538: Boeing 747-438, VH-OJH Bangkok, Thailand. Retrieved 24 August 2010, from http://www.atsb.gov.au/publications/investigation_reports/1999/AAIR/pdf/aair199904538_001.pdf.