As a companion piece for Discussion Topic 24-1, The Difference of Workload Priorities Between Taxi-out and Taxi-in, consider the following NASA ASRS event where a crew missed their parking gate during taxi-in. Referring to the discussion topic, notice how preconceptions, biases, distractions, and misplaced attention toward discretionary tasks interacted to result in their error. From NASA ASRS report #1404064 (italics added):
On taxi in to the gate in BWI, I taxied past our assigned gate towards the incorrect side of the concourse and required an amended taxi clearance to reverse back to our gate.
We departed BWI from Gate YY. Now, on the return leg to BWI we were assigned Gate XX. I conducted a routine arrival briefing prior to the top of descent. At the time, I briefed that we would taxi F, T, to Gate XX. Without referencing the chart, I misidentified the location of Gate XX from “memory”. It is on the same side as YY. I believe that I had an expectation bias of the even gates being [on one side] of the concourse because we had just operated out of an odd gate (YY) on the [other side]. The Pilot Monitoring (PM) did not catch my error in the briefing.
After landing on Runway 33L, we told Ground Control that we were assigned Gate XX. We were cleared to taxi F, T, to the gate. After receiving the clearance, the First Officer (PM) went off frequency to contact Operations. He was distracted receiving aircraft swap information as I taxied past Gate XX.
Another additive condition was another carrier wide body aircraft was being towed on the parallel taxiway, surrounded by emergency vehicles with lights flashing. As we taxied past the other aircraft, I wanted to make sure we had wingtip clearance as I was not sure if he was off his taxiway (it was difficult to see clearly at night with the emergency vehicle lights).
When we got to the end of the concourse and I began a turn [towards the gate], I first realized that the gate numbers were odd. I stopped the aircraft and advised Ground Control that I had “screwed up” our taxi and needed clearance to go back to Gate XX. The PM was just finishing communications with Operations and now realized, as I, [where] Gate XX was. Ground Control approved us for a 180 degree turn and clearance to taxi back to Gate XX. We taxied to Gate XX without further incident and no conflicts.
The error chain started when I did not do a thorough briefing by referencing the chart. The PM had an opportunity to trap my error, but fell into the same expectation bias. After landing, I should have caught what the taxi clearance was. The bright lights of the emergency vehicles were a distraction as was the extended ground call to Operations for the PM. These were additive conditions that should have been recognized and identified. Normally, at that point I may have caught that we were taxiing past Gate XX and the even gates.
The briefing and taxi error were my fault due to complacency and lack of thoroughness. We were fortunate that there were no traffic conflicts at this time of the evening. Had the same error occurred during peak operations, it could have caused significant congestion and potential safety conflicts.
To prevent future occurrences, I need to be more thorough with my briefings. Even when I think “I know”, I need to reference and view the ramp charts just as I do the Jeppesen charts. I also should have paid closer attention to our taxi clearance and not assumed. Lastly, I need to do a better job of engaging the PM during briefings and avoid the rote regurgitation of information that leads to PM missing errors on my part.
Points to consider:
- Operational familiarity: The report implies that the Captain was quite familiar with operating out of BWI (Baltimore/Washington International – Thurgood Marshall Airport). This was reflected by briefing their gate arrival without referencing the airport diagram. This allowed their misconception that Gate XX was on the opposite side of the terminal from previous gate, Gate YY (by assuming that all even numbered gates were on one side and all odd numbered gates were on the other). Both pilots made the same assumption. Ideally, the PM needs to capture errors like this. We don’t want PMs agreeing with the PFs, we want them verifying each facet of the game plan to detect and correct errors as early as possible. This reflects a one-sided briefing perspective (only the pilot flying dictating the game plan) instead of the interactive two-way briefing method (where both pilots work together to form the game plan). Their aligned perspectives effectively solidified their expectation bias that the gate would be where they thought it was (on the opposite side of the terminal from Gate YY) versus where it really was (adjacent to Gate XX). This kind of bias strongly influences future conceptions and choices because we treat them as “facts” that don’t require future verification or confirmation. Since they knew where their gate was, they never perceived a need to reconfirm the actual gate location or taxi routing using the ramp diagram.
- Distraction: On their way to the gate, the crew encountered a wide-body aircraft under tow and escorting emergency vehicles. This would understandably attract most of their attention. Concerned with wingtip clearance, the Captain was highly focused on getting clear. This type of event seems to create a psychological letdown when finally clear of the hazard. It can feel like, “okay, that [exceptional event that had our full attention] has ended, now we can relax and get back to normal taxi-in.” We feel a strong motivation to return to our familiar game plan. Solving a big problem creates an impression that we have solved all problems. Often, some lesser problems slip through undetected or mitigated. Having passed the wide-body aircraft under tow, we can envision this Captain breathing a sigh of relief at finally being able to taxi normally to the gate.
- Additive Conditions: The Captain referred to additive conditions. Additive conditions reflects the language of Risk and Resource Management (RRM) – covered extensively in Master Airline Pilot: Applying Human Factors to Achieve Peak Performance and Operational Resilience. They are complicating factors that urge us to focus more attention on understanding and handling emerging problems. Conditions interact in increasingly complex ways to create competing priorities that allow unpredictable outcomes to emerge. In this case, nighttime conditions and ramp congestion required their full attention. This intensified their plan continuation bias, increased the intensity/duration of distractions/disruptions, and encouraged continuing their flawed game plan.
- Discretionary actions: The FO had two opportunities to interdict the Captain’s misconception about the gate location. The first was during the arrival briefing while they were still in cruise flight. Had either pilot consulted their ramp diagram, they could have detected and corrected the misconception. Second, the FO engaged in time-consuming “off frequency” coordination with the station regarding an aircraft swap. While aircraft swaps are not operational concerns that we can do anything about during taxi-in, they represent major concerns with future task load. Especially if this crew routinely engaged in discretionary clean-up tasks during taxi-in, they would immediately feel behind as they now faced a much greater task load of gathering their personal items before scrambling to the swap aircraft (as compared with leaving all of their gear in place for a follow-on flight with the same aircraft). We can imagine that these concerns left the FO highly disengaged with the taxi-in process.
- Low Operational Priority: The taxi-in and gate arrival flight phases seemed to have low operational priority with both pilots. While they went through the steps to brief the taxi-in before top-of-descent, they admitted that they didn’t give it adequate attention – briefing it completely from memory versus referencing the ramp/gate diagram. This often occurs among highly proficient pilots operating frequently through familiar airports. Familiarity with a typical flight profile allows pilots to allocate more attention toward disruptions and less toward familiar operational details. In time, these normal features become cognitively automated. Settled within our comfort zone, we relegate these repetitive tasks to habit. While this frees up mental resources to deal with unplanned or exceptional events, habits tend to weaken error detection/mitigation. We counter this by mindfully following procedures. Familiar and unfamiliar airports are treated equally, even when the process feels unnecessary or redundant.
- Event Insignificance: In the end, this error/event proved to be fairly insignificant. It was quickly sorted out and they proceeded safely to their gate. Even so, we should not classify these kinds of errors as unimportant. In practice, many taxi-in errors remain so inconsequential that most pilots choose not to document them through event reporting. Also, they often misattribute them to conditions like adverse weather, day/night conditions, poor signage, worn taxi guidelines, etc. The importance of this topic is that it encourages us to raise our awareness level and attention focus to match high AOV aircraft movement (see Discussion Topic 24-1 and Master Airline Pilot for more on this topic). As Master Class pilots, we study ourselves to detect lapses when we allow discretionary tasks to migrate into inappropriate flight phases. Appropriate attention discipline is a Master Class skill that we continue to refine throughout our entire flying careers.
