Turkish A-330 Runway excursion at KTM due to cognitive lockup:March 2015

Turkish A330 4th March 2015 VNKT

Abstract On March 4th 2015, Turkish Airlines Flight TK-726 experienced a runway excursion whilst landing at Tribhuvan International Airport (TIA) at 01:59 hrs. TK-726 was operating a scheduled passenger flight from Istanbul to Kathmandu with a total of 224 passengers with 11 crew members (2 Cockpit and 9 cabin crew). During landing the aircraft touched down towards the left edge of Runway 02 with the left hand main landing gear off the paved runway surface. The aircraft veered further to the left and came to a stop on the grass area between taxiway D and C.

The probable cause of this accident is the decision of the flight crew to continue approach and landing below the minima with inadequate visual reference and not to perform a missed approach in accordance to the published approach procedure.

Other contributing factors of the accident are the probable fixation of the flight crew to land at Kathmandu and the deterioration of weather conditions that resulted in fog over the airport reducing the visibility below the required minima.

Read my paper on Cognitive Lockup from the link below:

Moray and Rotenberg (1989) have defined the term ‘cognitive lockup’ as the tendency of operators to deal with disturbances sequentially. Cognitive lockup, however, does not occur when people can perform all their tasks consecutively.

Cognitive lockup can also be defined as holding on to a task or sticking to a problem.

In terms of the task-switching paradigm, cognitive lockup can be considered as reluctance to switch to an alternative task or problem. (Meij, 2004).


In the scenario, the aircraft is in cruise phase and a thunderstorm is presented very close to the destination. This attracts the attention of the pilot, as it is not  clear if there is a need to divert to the alternate or not. The pilot keeps monitoring the movement and intensity of the thunderstorm. During this monitoring phase, a failure is introduced in one of the aircraft engines. The pilot recognizes the failure but does not react and continues to monitor the thunderstorm. After a while, the urgency to handle the engine malfunction is realized and the pilot begins to solve the engine malfunction task.

The cognitive lockup prevents the pilot from immediately switching task, from that of monitoring the thunderstorm to handling the engine malfunction. Figure 2 (Cacciabue, Hj lmdahl, Luedtke & Riccioli, 2011), shows the goal priorities of each goal over time during thunderstorm avoidance.

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Factors affecting

  • Sunk cost fallacy
  • Task completion
  • Time and task pressure
  • Framing effect


Pilots approaching the destination have invested a lot of time in their task and it is nearing completion. Task pressure of completing the flight and the framing of the policy with the primary task of landing at the destination increases the possibility and effect of cognitive lockup. As a result, the pilot will continue with the first task, that of landing at the destination, despite being unstable on approach or when performing a long landing. Carrying out a go-around can be inferred as task switching. This task will be carried out provided there is enough time to realize the consequences of persisting with the primary task. Since there is not enough time and the task completion is within sight, the pilots will continue and land.

Training has an effect of reducing cognitive lockup by increasing practicing task switching that of approach/flare followed by switching to the task of a go-around and reattempting a second time. The policy, if framed to depict a go-around and a diversion in a positive light will reduce the pressure of task completion from the pilots and they would be more prone to switching the task to go-around with ease.

Cognitive lockout is the primary reason for the reluctance to go-around. If task switching practice is increased, as compared to other tasks, in the trainings, there will be a significant drop in the number of unstable approaches and long landings.


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