FEAST Vigilance and Conflict Recognition 3 — Questions and Answers
Question 1: The signal detection theory concept of 'criterion' in ATC vigilance refers to:
- The threshold of evidence a controller requires before deciding a situation requires action (Correct answer)
- The number of aircraft a controller can track before performance degrades
- The time between radar sweeps and controller response to a deviation
- The minimum separation distance below which automatic alerts are triggered
Correct answer: The threshold of evidence a controller requires before deciding a situation requires action
The decision criterion is the internal threshold determining whether a given stimulus is 'enough' to warrant a response — a key SDT concept in vigilance research.
In Signal Detection Theory (SDT), a 'criterion' is the decision threshold: stimuli above it lead to a 'yes, this is a signal' response, stimuli below it lead to 'no, this is noise'. A liberal criterion means acting on weaker evidence (more hits but more false alarms). A conservative criterion means requiring stronger evidence (fewer false alarms but more misses). For ATC vigilance, an overly conservative criterion leads to missed conflicts; too liberal a criterion leads to unnecessary actions. FEAST research uses SDT to analyse candidates' vigilance profiles and identify those with dangerous criterion placements.
Question 2: A false alarm in ATC vigilance context means:
- A controller issues a conflict resolution instruction when no actual conflict exists (Correct answer)
- An automated alert activates for a situation that does not require action
- A pilot reports TCAS RA activation when the manoeuvre was unnecessary
- An emergency squawk is transmitted in error by a pilot
Correct answer: A controller issues a conflict resolution instruction when no actual conflict exists
A false alarm is a positive response (issuing an instruction) when no actual conflict exists — the controller perceived a conflict that was not real.
In SDT terms: a Hit = correct detection of a real conflict; a Miss = failing to detect a real conflict; a False Alarm = detecting a non-existent conflict; Correct Rejection = correctly identifying no conflict. For ATC vigilance, misses are most safety-critical (missed real conflicts), but false alarms are also operationally costly as unnecessary instructions disrupt traffic flow, increase pilot workload, and reduce controller credibility. FEAST measures both hit rates and false alarm rates to characterise candidates' complete vigilance performance profile.
Question 3: Research shows that STCA (Short-Term Conflict Alert) systems that generate many false alarms tend to produce an effect called 'alarm fatigue'. This means controllers will:
- Begin to treat STCA alerts with less urgency, increasing the risk of missing genuine conflicts (Correct answer)
- Develop faster response times by practicing responses to frequent alerts
- Become more vigilant because frequent alerts keep arousal levels high
- Turn off STCA systems to reduce distracting noise in the operational environment
Correct answer: Begin to treat STCA alerts with less urgency, increasing the risk of missing genuine conflicts
Alarm fatigue (also called alert fatigue) occurs when frequent false alarms cause operators to habituate to alerts, reducing their urgency response even to genuine warnings.
Alarm fatigue is a well-documented human factors problem in aviation and healthcare. When automated systems generate high numbers of false alarms, operators learn through conditioning that most alerts are spurious. This habituation reduces the urgency of the response — controllers may delay or deprioritise genuine STCA activations because experience tells them 'it's probably another false alarm'. This is a critical safety problem. Aviation regulators carefully manage false alarm rates in STCA systems. FEAST assesses whether candidates understand this dynamic and can maintain appropriate vigilance response regardless of prior false alarm rate.
Question 4: A 'near-miss incident' in ATC is defined as:
- An airborne encounter where separation is reduced below prescribed minima but no collision occurs (Correct answer)
- An aircraft that almost collides with terrain below minimum safe altitude
- A runway incursion where aircraft are within 100 metres of each other
- A controller error that is detected and corrected before any impact on separation
Correct answer: An airborne encounter where separation is reduced below prescribed minima but no collision occurs
A near-miss (or airprox) is an airborne event where separation falls below prescribed minima, constituting a separation infringement even if no collision results.
In ICAO and EUROCONTROL terminology, a 'near-miss' or 'airprox' (airborne proximity event) occurs when two aircraft are in flight and their separation reduces below the prescribed minimum. This is classified as a separation infringement even if no collision occurs. It is reportable and investigated as a safety incident. Near-misses result from failures in conflict detection, resolution, or execution. FEAST tests knowledge of this definition because controllers must understand that separation infringement (not just collision) constitutes a safety event requiring reporting and review.
Question 5: A controller's vigilance performance data shows: in the first 10 minutes of monitoring, hit rate = 98%, false alarm rate = 2%. In the second 10 minutes, hit rate = 85%, false alarm rate = 8%. What does this pattern indicate?
- Vigilance decrement with a liberal criterion shift — the controller is detecting more uncertain signals as alertness falls (Correct answer)
- Improved conflict recognition — the controller is identifying more potential conflicts over time
- Equipment calibration issues — the radar display is generating more targets in the second period
- Fatigue causing random errors equally in hit and false alarm rates
Correct answer: Vigilance decrement with a liberal criterion shift — the controller is detecting more uncertain signals as alertness falls
Declining hit rate AND increasing false alarm rate together indicate a criterion shift — the controller is using weaker evidence to trigger responses as attention degrades, producing more misses AND more false alarms.
In SDT terms, pure sensitivity decline (d' reduction) would reduce hits but may also reduce false alarms. An increase in both false alarms and hits would suggest a more liberal criterion. A reduction in hits WITH an increase in false alarms is paradoxical and indicates a liberal criterion shift combined with sensitivity reduction — the controller begins responding to weaker evidence (more false alarms) but still misses more genuine conflicts (lower hits) because their overall detection sensitivity has declined. This complex vigilance degradation pattern is studied in FEAST research and used to predict candidates' real-world vigilance resilience.
Question 6: The primary purpose of sector rotation (changing controllers between sectors every 1–2 hours) in ATC operations is:
- To counteract vigilance decrement by providing cognitive refreshment and preventing monotony-induced performance decline (Correct answer)
- To allow controllers to train on different sector types for certification purposes
- To reduce physical fatigue from sitting in the same position for extended periods
- To prevent controllers from becoming too familiar with specific aircraft callsigns
Correct answer: To counteract vigilance decrement by providing cognitive refreshment and preventing monotony-induced performance decline
Sector rotation is primarily a vigilance management technique — changing sectors refreshes attention, increases arousal, and counteracts the monotony-driven vigilance decrement.
Sector rotation is a fundamental human factors intervention in ATC. By rotating controllers between sectors every 1–2 hours (or with a break), the vigilance decrement is reset — the new sector provides novel stimulation that restores arousal and detection sensitivity. The cognitive refreshment prevents the sustained monotony that drives vigilance decrement. Physical break benefits are secondary. Training variety is an incidental benefit. FEAST personnel selection and training programmes consider vigilance robustness explicitly because controllers who are highly susceptible to vigilance decrement may struggle during unusually long single-sector spells during staff shortages.
FEAST Vigilance and Conflict Recognition 3
The signal detection theory concept of 'criterion' in ATC vigilance refers to: