The increased level of aircraft’s automation reduces the number of crew members needed in cockpit, but it demands the each pilot must be able to manage several tasks simultaneously. Under the situation of frequently dealing with concurrent tasks, crew preoccupation, interruption, and distraction with one task to the detriment of other tasks can result in a fatal error in the cockpit. ASRS (Aviation Safety Reporting System) reports disclose vulnerability to errors is mainly expressed in the lack of adequate monitoring and failing to perform a deferred action or an intended action (Dismukes, Loukopoulos & Kimberly, 2001).
Lapses in monitoring
Dismukes, Young and Sumwalt (1998) studied 107 ASRS reports in which crews paid not enough attention to one task while attempting to another task. “These reports revealed that a wide range of activities were not adequately attended” in these incidents (Dismuke et al, 2001, p.1). 69% of these ignored activities are associating with monitoring activities, such as monitoring the aircraft status or position, and monitoring the pilot who is flying. The large proportion of mistakes in monitoring may in some way reflect that the aircraft operation require a large amount of monitoring from pilots. Besides, monitoring is particularly vulnerable task because it is easy to be diverted or distracted by the demand of another concurrent task. Many accident reports have revealed that failure to monitoring can result in an aviation accident. An example from these cases presented is the air crash of British European Airways Flight 548 on 18 June 1972.
On June 18, 1972, a Hawker Siddeley Trident 1C airliner operated by British European Airways, Flight BE 548, from London Heathrow Airport to Brussels Belgium crashed near the town of Staines in no more than three minutes after takeoff from Heathrow airport. The crash killed 118 people on board. The inquiry finding determined that the crash was attributed to a deep stall caused by the captain failed to maintain the recommended airspeed, and did not set the airplane’s high-lift devices properly (the captain prematurely engaged the aircraft into autopilot at an incorrect climbing airspeed, where “After 19 seconds in the air the autopilot was engaged at 355 feet (108 m) and 170 knots (310 km/h); the autopilot’s airspeed lock was engaged even though the actual required initial climb speed was 177 knots (328 km/h)” (Wikipedia, 2011, in section of departure para.6). Other factors attributing to the crash were " pilot incapacitation" (captain probably sufferred heart attack before crash), "the low experience level of the co-pilot" (Wikipedia, 2011, para.2), and crew failure to monitor the airspeed and aircraft configuration. However, if the co-pilot could recognize the captain’s error by monitoring captain's flying (Note: monitoring the pilot who is flying is an important responsibility for pilot who is not flying), so what the result would be about this?
Video embedded from YouTube on 21 Oct2011
Lapses in prospective memory
In the Dismuke’s report (et al,1998), they also found that 22% of the neglected activities resulted from the failure to complete an attempting action – either an action is habitually completed, e.g., "retracting speed brakes after leveling off in a descent" (Dismuke etal, 2001,p.2); or an action which was delayed or lingered until a short while later but forgotten (e.g. running an interrupted checklist). It is easy to neglect or ignore to perform delaying (deferred) actions in cockpit operation because the desire to perform delayed actions usually must be reminded from memory at a time when a pilot is preoccupied with other tasks, lacking such a reminder, a pilot cannot remember to complete the deferred action. Also, delaying an action may cause the pilots to miss the cues which should remind them to complete other tasks, such as call out etc.
One air crash involved with crew failure to perform the deferred actions is the accident Northwest flight 255 on August 16, 1987.
On August 16, 1987. Northwest Airlines Flight 255 would perform a flight mission from Saginaw, Michigan, to Orange County, California, via Romulus, Michigan, and via Phoenix, Zrizona, but the flight crashed after take-off in Romulus. The accident killed all people on board, in addition to a 4-year-old girl. The NTSB determined that the probable cause of the crash was that the cockpit crew failed to use the taxi checklist to confirm the flaps and slats were configured properly for take-off. Another factor contributing to the accident was the failure of aircraft take-off warning system that did not alert the crew with the incorrect set of airplane’s flaps and slats (Wikipedia, 2011). Baron (n.d) also revealed the evidence provided from the cockpit voice recorder (VCR) showed that the crew did not complete the taxi checklist, on which the first item was going to remind the crew to configure the aircraft flaps and slats for take-off. Just when the airplane was pushed back for taxi, the firstt officer, who would have often started to run the taxi checklist at that time, but it, was instead by recording the updated ATIS (Automatic Terminal Information Service). Until later time he was finished the record, the aircraft had been taxied to the runway, and it was probable that he believed the configuration of the aircraft flaps and slats had been done (Baron, n.d.)…
Video embedded from YouTube on 21 Oct2011
Video embedded from YouTube on 21 Oct2011
The techniques for pilots to avoid the lapses in monitoring and lapses in prospective memory
Techniques for preventing lapses in monitoring
Dismuke (et al, 2001) suggested twenty techniques for preventing lapses in monitoring; these were placed into six categories:
1. Manage workload: reschedule the order of tasks to lower the workload during critical phase of flight (e.g. taxi, take-off, and landing, etc.) and vulnerable situation (e.g. unanticipated situation); allocate the responsibilities to each of crew members and persist it; and manage workload to keep it in an acceptable level (e.g. informing ATC that not be able to answer them at this time).
2. Realize the demands from concurrent or multiple tasks and allocate attention on each task: identify certain things to monitor and not make the attention only concentrate on one tasks, but rather switch attention to and fro periodically between tasks; balance attention between tasks and enforce discipline to prevent over-concentrate on either of them; and “break the concurrent task into subtasks and pause between subtasks to monitor” (Dismuke et al, 2001, p.2).
3. Pre-check the tasks beforehand so as to recognize critical juncture and set up monitoring: pre-check and brief the procedures for take-off in crew meeting, and discuss the operation of flight plan and assure pilot flying (PF) has established task correctly.
4. “Raising red flag in the vulnerable situation” (Dismuke et al, 2001, p.2) and pay particular attention on it: notice pilot not flying (PNF) with announce when going head-down, and pilot flying (PF) regard the situation as high risk when PNF take eyes away from the monitoring.
5. Give high priority on neglected or ignored tasks: give higher priority to monitoring task than others, and assign conflict avoidance priority over searching for traffic.
6. Generate reminded mechanism with visual and auditory functions: “PNF call out progress so PF can monitor while performing other tasks” (Dismuke et al, 2001, p.2).
Techniques for preventing lapses in prospective memory
Dismuke (et al, 2001) also suggested seven techniques for preventing lapses in prospective memory; these were placed into five categories:
1. “Create a habit linking memory item to habitual actions: always turn wheel light on when landing clearance received, and make light switch part of final scan before landing; always check landing clearance at 1000 foot call; always check landing clearance at outer marker; put ground control frequency in standby radio when cleared to land and make radio head part of final scan; add landing clearance to final checklist as personal technique; and do descent checklist (and set altimeters) at FL 180” (Dismuke et al, 2001, p.2).
2. Manage workload: manage workload to keep it in an acceptable level; allocate the responsibilities to each of crew members and persist it; and First Officer fly the aircraft so Captain can handle the abnormal.
3. Generate reminded mechanism with visual and auditory functions: “hold checklist or mike or keep hand on radio until call to tower” (Dismuke et al, 2001, p.3); write the ATC instruction on paper; and put descent checklist at a visible place till altimeter reset.
4. Implementing task immediately: “call tower early (even though instructed to delay call); and set PNF altimeter or standby altimeter as soon as possible, then set PF altimeter at FL 180” ((Dismuke et al, 2001, p.3).
5. Miscellaneous: strengthen memory retrieval (e.g. loudly repeat the ATC instruction); strictly follow SOPs.
British European Airways Flight 548. (2011, September 18). In Wikipedia, The Free Encyclopedia. Retrieved from http://en.wikipedia.org/wiki/British_European_Airways_Flight_548
Baron, R. (n.d.). Pilot and memory: A study of a fallible human system. AirlineSafety. Com. Retrieved from Google: http://www.airlinesafety.com/editorials/PilotsAndMemory.htm
Didmuke, K., Young, G., Battelle, R. S. (1998). Cockpit interruptions and distractions. ASRS Directline, 10. 4-9. Retrieved from Google Scholar: http://scholar.google.co.nz/scholar
Dismukes, R. K., Loukopoulos, L. D., & Kimberly, K. J. M. A. (2001). The challenges of managing concurrent and deferred tasks. Retrieved from Google Scholar: http://scholar.google.co.nz/scholar
GrandCentraldepot. (2009 February 24). British European Airways Flight 548 Crash of a Trident airliner Retrieved on 21 Oct 2011 from http://www.YouTube.com
Jblinck. (2010 March 27). Northwest Airlines Flight 255 4-5. Retrieved on 21 Oct 2011from http://www.YouTube.com
Northwest Airlines Flight 255. (2011, September 18). In Wikipedia, The Free Encyclopedia. Retrieved from http://en.wikipedia.org/wiki/Northwest_Airlines_Flight_255
Theairtran737. (2011 May 26). Northwest Airlines Flight 255. Retrieved on 21 Oct 2011 from http://www.YouTube.com