This article by Key Dismukes, Grant Young and Robert Sumwait is based on their research at NASA to study the problem of crew preoccupation. They reviewed NTSB reports of accidents attributed to crew error and concluded that nearly half of them involved lapses of attention associated with interruptions, distractions, or preoccupation with one task to the exclusion of another.

They found four broad categories of competing activities which distracted or preoccupied pilots:communication, head-down work, searching for VMC traffic and responding to abnormal situations.

The full report, six pages, is available on the NASA website as a PDF. However, it is a very dense read. I was more interested in this excerpt which focuses on examples from each of the categories that the researchers defined. This was originally published by ASRS (Aviation Safety Reporting System) Directline and I am reprinting it with permission.

Although the research was done some time ago, I found the results fascinating and still very pertinent. I hope you will too.

Cockpit Interruptions and Distractions

by

• Key Dismukes, Ph.D, NASA Ames Research Center
• Grant Young, Ph.D., New Mexico State University
• Captain Robert Sumwalt, Battelle

Category 1: Communication

Copilot was a new hire and new in type; first line flight out of training IOE. Copilot was hand-flying the aircraft on CIVET arrival to LAX. I was talking to him about the arrival and overloaded him. As we approached 12,000 feet (our next assigned altitude) he did not level off even under direction from me. We descended 400 feet low before he could recover. I did not realize that the speed brakes were extended, which contributed to the slow altitude recovery. (# 360761)

In this example, the Captain was attempting to help the new First Officer, but the combination of flying the airplane and listening to the Captain was too much for the new pilot. Tellingly, the act of talking distracted the Captain himself from adequately monitoring the status of the aircraft.

Thirty-one of these incidents involved altitude deviations or failure to make a crossing restriction. In 17 of these 31 incidents (and 68 of the total 107 incidents) the crews reported being distracted by some form of communication, most commonly discussion between the pilots, or between a pilot and a flight attendant. Most, although not all, of these discussions were pertinent to the flight. However, in many cases the discussion could have been deferred. We later discuss how crews can schedule activities to reduce their vulnerability to distraction.

Research studies have shown that crews who communicate well tend to perform better overall than those who do not. But conversation has a potential downside because it demands a substantial amount of attention to interpret what the other person is saying, to generate appropriate responses, to hold those responses in memory until it is one’s own time to speak, and then to utter those responses. One might assume that it is easy to suspend conversation whenever other tasks must be performed. However, the danger is that the crew may become preoccupied with the conversation and may not notice cues that should alert them to perform other tasks. Special care is required to avoid distraction when others enter the cockpit, because they may not recognize when the pilots are silently involved in monitoring, visual search, or problem-solving.

Category 2: Head-Down Work

…Snowing at YYZ. Taxiing to runway 6R for departure. Instructions were taxi to taxiway B, to taxiway D, to runway 6R….as First Officer I was busy with checklists [and] new takeoff data. When I looked up, we were not on taxiway D but taxiway W…ATC said stop…. (# 397607)

In a review of airline accidents attributed primarily to crew error over a 12-year period,4 the NTSB concluded that failure to monitor and/or challenge the Pilot Flying contributed to 31 of the 37 accidents. In 35 of the ASRS incidents we studied, the Pilot Not Flying reported that preoccupation with other duties prevented monitoring the other pilot closely enough to catch in time an error being made in flying or taxiing. In 13 of these 35 incidents (and 22 of the total 107 incidents), the Pilot Not Flying was preoccupied with some form of head-down work, most commonly paperwork or programming the FMS.

Monitoring the Pilot who is flying or taxiing is a particularly challenging responsibility for several reasons. Much of the time the monitoring pilot has other tasks to perform. Monitoring the other pilot is much more complex than monitoring altitude capture because the other pilot is performing a range of activities that vary in content and time course. Thus, it is sometimes difficult for the monitoring pilot to integrate other activities with monitoring because he or she cannot entirely anticipate the actions of the other pilot. Furthermore, serious errors by the pilot who is flying or taxiing do not happen frequently, so it is very tempting for the pilot who is not flying to let monitoring wane in periods of high workload.

Periods of head-down activity, such as programming the FMS, are especially vulnerable because the monitoring pilot’s eyes are diverted from other tasks. Also, activities such as programming, doing paperwork, or reviewing approach plates, demand such high levels of attention that attempting to perform these tasks simultaneously with other tasks substantially increases the risk of error in one task or the other. Some FMC entries involving one or two keystrokes can be performed quickly and may be interleaved with other cockpit tasks. However, attempting to perform longer programming tasks, such as adding waypoints or inserting approaches during busy segments of flight, can be problematic. It is not possible for the Pilot Not Flying to reliably monitor the Pilot Flying or the aircraft status during longer programming tasks, and it is difficult to suspend the programming in midstream without losing one’s place.

Category 3: Searching for VMC Traffic

PRADO 5 Departure. Cleared to climb (and) received TCASII TA (which) upgraded to an RA, monitor vertical speed. While searching for the traffic we went past the NIKKL intersection…for the turn to the TRM transition. We had discussed the departure before takeoff; special procedures, combined with many step climb altitudes in a short/time/distance, made this a more demanding departure than most. Next time on difficult departures I will use autopilot sooner…will try to be more vigilant in dense traffic areas. (# 403598)

In 16 incidents crews failed to turn as directed by ATC on the SID or STAR they were following. The crews reported various activities competing for their attention; in three cases the activity was searching for traffic called out by ATC or TCAS. Altogether, crews reported searching for traffic as a competing activity in 11 of the 107 incidents. Searching for traffic takes the pilot’s eyes away from monitoring aircraft position and status, and also demands substantial mental attention. If the conflict is close the urgency may further narrow the focus of attention.

One of the insidious traps of interruptions is that their effects sometimes linger after the interruption. For example, descending through 4500 feet, a crew might be instructed to report passing through 3000 feet. They might then respond to and quickly resolve a traffic alert, but forget the instruction to report by the time they reach 3000 feet. In this hypothetical example, searching for traffic preempts the reporting instruction from the crew’s conscious awareness. The instruction presumably is still stored in memory in an inactive form, and if reminded, the crew probably will recognize that they were given the instruction. However, lacking such a reminder and being preoccupied with other activities, they do not remember to contact ATC as they pass through 3000 feet.

Category 4 Responding to Abnormal Situations

In 13 incidents crews failed to reset their altimeters when passing through the transition altitude (18,000 feet MSL in the United States and Canada). It is especially easy to forget to reset altimeters if this action is not linked in pilots’ minds to other actions. (For this reason some pilots make resetting altimeters part of a cluster of action items they routinely perform together, e.g., making a passenger announcement and turning on the seat belt sign. Some companies make resetting altimeters part of the descent checklist.) In principle, the problem is similar to that of monitoring for altitude level-off, except more vulnerable to error. In air carrier operations the crew is normally aided with altitude level-off by altitude alerting devices and by the formal procedure of making a thousand-foot call, confirmed by both pilots, before reaching the assigned altitude.

Two of the crews reporting to ASRS thought that they forgot to reset their altimeters stated they were preoccupied with an abnormal situation. Altogether, abnormals were a factor in 19 of the 107 incidents. Ironically, it seems that one of the biggest hazards of abnormals is becoming distracted from other cockpit duties. Abnormals easily preempt crews’ attention for several reasons. Recognizing the cockpit warning indicators, identifying the nature of the problem, and choosing the correct procedure require considerable attention. Crews have much less opportunity to practice abnormal procedures than normal procedures, so choosing and running the appropriate checklists requires more effort and greater concentration of mental resources than running normal checklists. Also, in situations perceived to be urgent or threatening, the normal human response is to narrow the focus of attention, which unfortunately tends to diminish mental flexibility and reduce ability to analyze and resolve non-routine situations.