Pilots have many tasks to perform; these are normally shared between the pilot flying (PF) and the pilot not flying (PNF). Flight crew workload varies, even during routine flights, from low to high and will rise in the event of abnormal weather conditions or aircraft malfunctions. During high workload, flight crew are especially vulnerable to error if their strategies for effective multi tasking break down. This is the aspect of workload considered here. However, during periods of low workload in the cruise, a different sort of error vulnerability may arise which stems from the low Level of Arousal which typifies this flight phase and sometimes from Complacency as well.
Periods of high workload
- Engine start and push back, taxi out, take-off and initial climb, standard instrument departure (SID);
- Descent, approach and landing, and especially during any go-around;
- Uncommon situations such as equipment malfunction or adverse weather;
- Emergency situations.
- Pilot line training
- Flight crew may mis-hear, misunderstand or mis-set an ATC clearance passed during a period of high work-load, leading to:
- Level Bust
- Controlled Flight into Terrain (CFIT);
- Loss of separation from other aircraft;
- Unstabilised approach;
- The pilot may be distracted from his/her primary tasks resulting in an error in handling or managing the aircraft.
- The Cross-checking Process that exists on the flight deck between the pilot flying (PF) and the pilot not flying (PNF).
- The read-back/hear-back procedure, which allows the ATCO to verify that the pilot has received the message correctly.
- The departure or arrival runway is changed during a high-workload period and the flight crew have insufficient time to re-brief for the procedures. As a consequence, the flight:
- Does not follow the correct SID for the changed runway; or,
- Does not execute a subsquent go-around as precribed;
- The flight crew misses or incorrectly interprets a message from ATC, as a result of which the flight:
- Taxis to wrong runway or uses the wrong route, possibly entering an active runway without clearance;
- Follows the wrong departure clearance after take-off or climbs above a limiting altitude/flight level;
- Commences approach without clearance;
- An approach is continued to a landing when a landing clearance has not been given.
- The flight crew are interrupted in the course of carrying out a flight-deck drill and omit a vital action or check.
- Multiple frequency changes are often given during high workload periods following takeoff and during the SID. This can cause confusion and distraction from important monitoring tasks.
- Severe weather conditions or aircraft malfunction can aggravate high work-load situations.
- Commence preparation for high workload periods as soon as possible;
- Attempt to anticipate possible changes in clearance;
- Ensure that both pilots listen to critical messages.
- Give clearances, including re-clearances, in good time, if possible anticipating periods of high pilot workload;
- Where possible, avoid late changes to a clearance especially where the change necessitates lengthy re-briefing by pilots (e.g. change of take-off runway, change of standard instrument departure (SID), change of landing runway).
Pilots and ATCOs:
- Use standard phraseology and insist on the correct read-back procedure.
- EASA Flight Time Limitations (FTL) - Q&A, August 2015
- Fighting Pilot Fatigue, video by Boeing’s Fatigue Risk Management team in partnership with Delta airlines to portray the effects of fatigue on pilots. It describes technologies in the flight deck that can monitor and prevent fatigue-related events.
- Perceived Pilot Workload and Perceived Safety of RNAV (GNSS) Approaches, ATSB Australia, December 2006.