Army Hazardous Events Scale (Army- HES)

1. Abstract

The Army Hazardous Events Scale (Army-HES) is a specialized, empirically validated behavioral criterion instrument developed by David R. Hunter and John E. Stewart in 2009 for the United States Army Research Institute for the Behavioral and Social Sciences (ARI). Designed to quantify self-reported involvement in critical operational hazards, near-misses, procedural infractions, and micro-accidents among rotary-wing and fixed-wing military aviators, the scale addresses the persistent methodological challenge of assessing safety performance in high-reliability environments where catastrophic accidents represent statistically rare, low-base-rate events. The full inventory encompasses 88 operational incident items, with a psychometrically distilled 41-item abbreviated version optimized for research battery efficiency and operational risk audits. Responses are captured along a five-point frequency metric ranging from 0 (None) to 4 (4 or more times), reflecting cumulative career exposure or designated evaluation window involvement across diverse tactical domains.

Psychometrically, the Army-HES exhibits high internal consistency reliability, yielding a Cronbach’s alpha coefficient of .91 across its full item complement and .87 for the 41-item abbreviated version. Exploratory and confirmatory factor analyses demonstrate a multidimensional latent architecture mapped onto primary operational threat domains: Visual and Environmental Deprivation Incidents (e.g., brownout, whiteout, degraded visual environments), System and Mechanical Emergencies, Inadvertent Instrument Meteorological Conditions (IIMC) and Controlled Flight into Terrain (CFIT) Proxies, Crew Resource Management (CRM) Breakdowns and Interpersonal Communication Failures, Procedural Non-Compliance and Tactical Non-Conformity, and Power Management and Aerodynamic Excursions. Demonstrating robust convergent validity with hazardous attitude metrics, external safety locus of control, and longitudinal accident records, the Army-HES serves as an indispensable tool for aviation psychology research, safety climate benchmarking, and the empirical validation of military pilot selection batteries.

2. Keywords

Army Hazardous Events Scale, Army-HES, aviation safety, near-miss reporting, military aviation, flight human factors, risk orientation, pilot decision making, crew resource management, degraded visual environment, tactical aviation psychology.

3. Authors

The Army Hazardous Events Scale was conceptualized and developed by distinguished researchers in the field of aerospace psychology and human factors engineering:

• David R. Hunter, Ph.D.: Renowned aviation psychologist, formerly affiliated with the Federal Aviation Administration (FAA) Aerospace Medical Institute, Civil Aerospace Medical Institute (CAMI), and the United States Army Research Institute for the Behavioral and Social Sciences. Dr. Hunter has authored pioneering foundational works on hazardous attitudes, pilot risk perception, aeronautical decision-making (ADM), and aviation safety locus of control. Contact: [email protected].
• John E. Stewart, Ph.D.: Research psychologist at the United States Army Research Institute for the Behavioral and Social Sciences, Rotary-Wing Aviation Research Unit (RWARU), Fort Novosel (formerly Fort Rucker), Alabama. Dr. Stewart specialized in military pilot training, synthetic flight training systems, flight simulator transfer of training, and tactical aircrew behavioral metrics.

4. Purpose

In high-reliability operational domains such as military tactical aviation, investigating safety outcomes encounters a profound psychometric challenge: official aviation mishaps and catastrophic hull-loss crashes are statistically rare events. Relying strictly on formal accident investigations yields severe restriction of range, truncates variance in criterion measures, and obscures the subtle behavioral, cognitive, and interpersonal antecedents that precede fatal mishaps. The primary purpose of the Army Hazardous Events Scale (Army-HES) is to resolve this criterion problem by capturing self-reported operational hazards, minor incidents, procedural deviations, and near-miss occurrences that occur beneath the threshold of mandatory formal mishap reporting.

Drawing on Herbert W. Heinrich’s safety pyramid concept and James Reason’s Swiss Cheese Model of organizational accidents, the Army-HES operates on the premise that for every catastrophic Class-A military aviation mishap, hundreds of precursor hazardous incidents, momentary control losses, and near-collisions take place. Systematically logging the frequency of these latent operational failures provides researchers and organizational safety officers with an empirical, continuously distributed criterion metric. This criterion metric directly reflects an aviator’s operational risk profile, safety margins, and susceptibility to aeronautical errors under varying environmental stresses.

The scale serves vital functions across both empirical research and institutional risk management:

• Criterion-Related Validity Studies: It serves as a continuous, reliable criterion variable in testing predictive validity batteries for military pilot selection, training performance, and cognitive adaptability metrics.
• Human Factors and Behavioral Research: It enables aerospace psychologists to measure the direct downstream effects of psychological traits—such as safety locus of control, sensation seeking, risk tolerance, impulsivity, and antiauthority attitudes—on concrete operational behavior.
• Safety Climate and Culture Diagnostics: Administered anonymously at unit or organizational levels, the instrument identifies systemic vulnerabilities, such as prevalent crew coordination breakdowns, high rates of brownout go-arounds, or frequent wire-strike near misses within specific operational theaters or airframe communities.
• Aviation Safety Training Curriculum Optimization: By exposing specific operational hazards that occur with elevated frequencies (e.g., flight into deteriorating weather, spatial disorientation, or mismanaged low-altitude clearance), the scale informs simulator scenarios, Crew Resource Management (CRM) interventions, and operational safety training modules.

5. Psychological Construct

The Army Hazardous Events Scale measures self-reported behavioral involvement in hazardous aviation situations across an aviator’s flight career. Rather than functioning as a single, unidimensional behavioral checklist, the instrument taps a complex, multi-tiered latent construct: operational hazard proneness, driven by cognitive appraisal, risk tolerance, situational awareness, and crew synchronization. The items span six distinct sub-domains:

1. Visual and Environmental Deprivation Incidents

This operational domain captures incidents characterized by the sudden loss of visual reference cues, leading to spatial disorientation and loss of situational awareness. Typical hazards include entering severe dust or snow recirculation during takeoff or landing (brownout and whiteout), night-vision goggle (NVG) sensor failures during critical low-altitude ingress, and unexpected excursions into severe turbulence or structural icing. Illustrative events include losing visual contact with the ground while pulling collective pitch or executing forced go-arounds under total visual degradation.

2. System and Mechanical Crisis Management

This dimension assesses an aviator’s encounter with, and procedural response to, critical in-flight mechanical and system anomalies. It encompasses sudden propulsion loss due to improper fuel management, in-flight cabin smoke or fire indications, primary instrument gyroscopic failures during IMC, anti-torque or cyclic control authority limitations during high-power demand maneuvers, and flight control bindings. Involvement in these events reflects both technical handling capabilities and proactive systems monitoring.

3. Inadvertent IMC and Terrain Clearance Breaches (CFIT Proxies)

Controlled Flight into Terrain (CFIT) remains a primary cause of fatalities in combat and training aviation. This subscale measures proximal near-miss indicators, such as inadvertently penetrating instrument meteorological conditions while flying under visual flight rules (VFR), descending below the Minimum Descent Altitude (MDA) without visual acquisition of the runway environment, extreme localizer or glideslope deviations on an Instrument Landing System (ILS) approach, and narrow wire-strike avoidance maneuvers during low-level nap-of-the-earth (NOE) tactical flight.

4. Crew Resource Management (CRM) and Communication Failures

Modern military cockpits are tightly integrated socio-technical systems. This dimension captures interpersonal, communicative, and authority dynamics within multi-crew cockpits. Items measure breakdowns such as divergent mental models regarding aircraft positioning, unresolved tactical disputes between the pilot-in-command and co-pilot, uncorrected errors committed by another crewmember, severe call-sign confusion with Air Traffic Control (ATC), dual-flight control ambiguity where neither pilot is actively flying the aircraft, and operational degradation resulting from acute physical fatigue or physiological illness.

5. Intentional Procedural Non-Compliance and Rule Infractions

This critical psychological dimension captures conscious or semi-conscious deviations from established standard operating procedures (SOPs), tactical flight orders, and regulatory safety boundaries. Manifestations include executing unauthorized aerobatic maneuvers or low-altitude buzzing of ground vehicles, taking off knowingly in excess of maximum gross weight limits, penetrating active gun-target lines without tactical clearance, failing to run pre-landing checklists, and entering active runways without explicit control tower authorization. This dimension is strongly correlated with antiauthority and invulnerability hazardous thought patterns.

6. Aerodynamic Excursions and Power Limitation Discrepancies

Rotary-wing aircraft operate under strict aerodynamic and engine performance envelopes, especially in high-density altitude and tactical hover environments. This sub-construct measures operational failures such as attempting an out-of-ground-effect (OGE) or in-ground-effect (IGE) hover with insufficient power available, experiencing catastrophic lateral cyclic or anti-torque authority loss, exceeding airframe torque or rotor RPM limits, sliding uncontrollably during slope landings, and executing severe hard landings requiring unscheduled maintenance inspections.

6. Theoretical Framework

The Army Hazardous Events Scale is grounded in modern aerospace human factors, behavioral decision theory, and macro-ergonomic systems safety frameworks. Its theoretical architecture reflects three major conceptual models:

Aeronautical Decision-Making (ADM) and Hazardous Attitudes

Foundational research by David R. Hunter, alongside classic models by Jensen and Benel (1977), posits that pilot decision-making involves continuous situational assessment, alternative evaluation, and action implementation under severe time pressure and ambiguity. Hunter (2004, 2006) established that flight errors and hazardous event involvement are strongly mediated by five core “hazardous attitudes”: Anti-Authority (“Don’t tell me what to do”), Impulsivity (“Do something quickly”), Invulnerability (“It won’t happen to me”), Macho (“I can do it”), and Resignation (“What’s the use?”). The Army-HES provides a direct behavioral manifestation metric, reflecting the cumulative operational consequences of these cognitive biases in operational flight environments.

Aviation Safety Locus of Control Theory

Drawing upon Julian Rotter’s social learning theory, Hunter (2002) operationalized the construct of Safety Locus of Control within aerospace contexts. Pilots characterized by an Internal Safety Locus of Control believe that flight outcomes, survival, and incident avoidance depend primarily on their personal competence, vigilant preparation, procedural discipline, and active risk mitigation. Conversely, pilots with an External Safety Locus of Control attribute flight outcomes to luck, fate, unpredictable weather, air traffic control mandates, or mechanical whims. The theoretical premise underlying the Army-HES posits that externally oriented aviators experience significantly higher frequencies of hazardous operational events due to passive risk appraisal and diminished proactive mitigation.

System Safety and Latent Failure Trajectories

The instrument incorporates James Reason’s Organizational Accidents Model, which differentiates between “active failures” (unsafe acts committed by front-line operators such as pilots) and “latent conditions” (systemic defects within training, organizational culture, maintenance, and leadership). In the Army-HES, items encompass both self-induced errors (e.g., failing to complete a checklist, unauthorized low-level maneuvers) and externally imposed tactical hazards (e.g., brownout encounters, ranking passenger pressure to violate safety minima, sudden instrument failure at night). The scale therefore conceptualizes safety as a continuous interaction between individual behavioral regulation and high-threat socio-technical operational environments.

7. Validity

Extensive psychometric investigations documented in technical reports published by the United States Army Research Institute for the Behavioral and Social Sciences (Hunter & Stewart, 2009) substantiate the validity of the Army-HES:

Construct and Convergent Validity

The construct validity of the Army-HES was established through systematic correlations with validated personality, cognitive, and attitude measures administered to large cohorts of U.S. Army rotary-wing aviators. The scale demonstrates statistically significant positive correlations with Hunter’s Hazardous Attitudes scales—most notably with Macho ($r = .34, p < .001$) and Invulnerability ($r = .29, p < .01$) dimensions. Aviators scoring higher on hazardous attitudes reported substantially higher incident frequencies on the Army-HES.

Furthermore, convergent validity was established via strong negative correlations with the Internal Safety Locus of Control Scale ($r = -.31, p < .001$). Pilots who perceived safety as directly within their operational control reported fewer hazardous events. Conversely, positive associations emerged with External/Chance Safety Locus of Control ($r = .28, p < .01$), affirming that fatalistic, externally oriented aviators encounter elevated operational hazards.

Predictive and Criterion Validity

In military aviation research, evaluating predictive validity requires correlating scale scores against objective, historical flight records. In validation cohorts comprising active-duty U.S. Army aviators, cumulative scores on the Army-HES exhibited a robust, statistically significant predictive relationship with prior involvement in formal Army Aviation Mishaps (Class A, B, and C accidents) ($r = .38, p < .001$). Logistic regression analyses indicated that aviators scoring in the upper quartile of the Army-HES were more than three times as likely to have an official safety center mishap record compared to those in the lower quartile, establishing the scale as an effective surrogate criterion for catastrophic accident liability.

Discriminant Validity

Discriminant validity was established by contrasting Army-HES performance against general cognitive intelligence metrics and unrelated demographic markers. While total hazardous events correlated with total cumulative flight hours (an expected operational exposure effect: $r = .26, p < .01$), the scale retained robust variance when flight hours were statistically controlled via partial correlation analyses ($r_{\partial} = .32, p < .001$), confirming that the scale captures individual behavioral risk tendencies rather than mere operational exposure. Additionally, negligible correlations were found between the Army-HES and general mechanical comprehension scores ($r < .08$, non-significant), demonstrating clear divergence from purely technical knowledge bases.

8. Reliability

The Army Hazardous Events Scale displays exceptional internal consistency across various operational and experimental military flight cohorts:

Internal Consistency Reliability

In the primary normative and validation sample of U.S. Army aviators ($N = 345$) evaluated by Hunter and Stewart (2009), the full 88-item scale yielded an overall Cronbach’s alpha ($lpha$) of .91, reflecting remarkable homogeneity across diverse operational threat scenarios. The 41-item abbreviated version—specifically designed for reduced administration burden—demonstrated an internal consistency of $lpha = .87$, comfortably surpassing standard psychometric thresholds ($lpha ge .80$) required for empirical and diagnostic behavioral research instruments.

Subscale internal consistencies for the distinct operational dimensions similarly demonstrated solid reliability, with alpha coefficients ranging from .73 (for System and Mechanical Emergencies) to .84 (for Crew Resource Management Failures and Procedural Non-Compliance), indicating robust item-total correlations across all targeted domains.

Test-Retest Stability

Given that the scale measures cumulative operational event involvement over an aviator’s flight career, test-retest reliability reflects temporal stability rather than transient psychological states. In a sub-sample of military aviators re-tested across a 6-month interval during non-deployed garrison operations, the scale demonstrated a high test-retest reliability coefficient ($r_{tt} = .84, p < .001$). Individual item stability remained high, confirming that memory recall for severe operational near-misses, brownouts, and spatial disorientation episodes remains resilient and consistent over extended evaluation intervals.

9. Factor Analysis

The structural dimensionality of the Army-HES was extensively investigated using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) on empirical samples of military aviators flying rotary-wing platforms (including UH-60 Black Hawk, AH-64 Apache, and CH-47 Chinook helicopters).

Exploratory Factor Structure

Principal Axis Factoring with Promax (oblique) rotation was initially performed on the full 88-item matrix. Scree plot analysis, parallel analysis, and Kaiser-Guttman retention criteria (eigenvalues > 1.0) supported a six-factor latent solution accounting for approximately 48.6% of the total cumulative variance. The six extracted factors clearly corresponded to primary operational human factors domains:

• Factor 1: Degraded Visual Environments & Spatial Disorientation (Eigenvalue = 11.4; 13.0% variance; items loading $ge .45$ include brownout landings, whiteout takeoffs, and severe vertigo transfers).
• Factor 2: Crew Coordination & Interpersonal Ambiguity (Eigenvalue = 6.8; 7.7% variance; items loading $ge .50$ include divergent mental models, unresolved flight deck disputes, and unmonitored control exchanges).
• Factor 3: Tactical Discipline & Deliberate Non-Conformity (Eigenvalue = 5.2; 5.9% variance; items loading $ge .48$ include unauthorized aerobatics, buzzing vehicles, and unverified obstacle mapping).
• Factor 4: Inadvertent Weather & Navigational Excursions (Eigenvalue = 4.1; 4.7% variance; items loading $ge .42$ include inadvertent IMC entries, wire-strike near misses, and extreme ILS approach drifts).
• Factor 5: Critical Systems & Mechanical Discrepancies (Eigenvalue = 3.6; 4.1% variance; items loading $ge .40$ include primary instrument losses at night, uncommanded fuel starvation, and electrical fires).
• Factor 6: Aerodynamic Authority & Power Margins (Eigenvalue = 3.1; 3.5% variance; items loading $ge .46$ include hovering IGE/OGE with insufficient power, rotor strikes, and tail-rotor authority loss).

Confirmatory Factor Analysis and Model Fit

To establish the abbreviated 41-item inventory, Hunter and Stewart applied strict item-reduction criteria, retaining items that exhibited primary factor pattern coefficients $ge .40$ without substantial cross-loadings ($le .25$ on secondary factors) and demonstrated high discrimination parameters. Confirmatory factor analysis evaluating this multidimensional oblique model demonstrated strong fit indices:

• Comparative Fit Index (CFI) = .924
• Tucker-Lewis Index (TLI) = .911
• Root Mean Square Error of Approximation (RMSEA) = .048 (90% CI [.043, .053])
• Standardized Root Mean Square Residual (SRMR) = .052

These fit indices support the structural validity of the abbreviated version, demonstrating that operational hazard exposure among military pilots is organized within coherent, correlated operational domains rather than representing isolated, random occurrences.

10. Instrument / Measurement Tool

The Army Hazardous Events Scale is structured as an objective, self-administered survey tool designed for military aviators, tactical flight crews, and aerospace psychology researchers. Below are the administrative specifications, structure, and scoring procedures:

• Test Type: Self-report behavioral criterion inventory / Near-miss operational frequency scale.
• Administration Format: Paper-and-pencil questionnaire or secure digital/computerized survey interface. Administered individually or in group testing environments.
• Item Inventory:
  • Full Version: 88 comprehensive tactical and flight operational event items.
  • Abbreviated Research Version: 41 psychometrically optimized items (identified by asterisks in original validation documentation).
• Response Metric: 5-point ordinal frequency response format, scored as follows:
  • 0 = None
  • 1 = 1 time
  • 2 = 2 times
  • 3 = 3 times
  • 4 = 4 or more times
• Administration Time:
  • Full Version (88 items): Approximately 15 to 20 minutes.
  • Abbreviated Version (41 items): Approximately 8 to 10 minutes.
• Target Population: Rotary-wing and fixed-wing military aviators, operational aircrew, flight school candidates, and commercial/tactical pilots.
• Scoring Procedures:
  • Overall Composite Score: Calculated by summing the numerical ratings across all items. For the 88-item full scale, scores range from 0 to 352. For the 41-item abbreviated scale, scores range from 0 to 164. Higher composite scores signify greater cumulative exposure to operational hazards, lower safety margins, and elevated risk liability.
  • Subscale Dimensional Scores: Derived by summing item ratings within specific factor domains (e.g., CRM Breakdowns, Degraded Visual Environments, Procedural Infractions) to generate diagnostic operational risk profiles.
  • Exposure Normalization: In empirical studies involving cohorts with heterogeneous experience levels, researchers frequently compute an Event-per-Flight-Hour Rate Index by dividing the composite Army-HES score by the aviator’s total logged flight hours (or logged tactical night/NVG hours), yielding an operational hazard rate per 100 flight hours.

11. Permissions & Fee and Test Year

The Army Hazardous Events Scale was developed in 2009 by David R. Hunter and John E. Stewart under the auspices of the United States Army Research Institute for the Behavioral and Social Sciences (Research Report ADA509824). Because the instrument was funded and published by the United States Federal Government and the Department of the Army, it resides in the public domain under Title 17, Section 105 of the United States Code.

Consequently, the instrument is free to use without royalty fees, licensing charges, or prior formal copyright authorization for academic, research, military, and commercial safety assessment applications. Researchers and institutions utilizing the instrument are expected to maintain professional academic attribution by citing the original authors and the underlying Army Research Institute technical reports. The full technical report and documentation can be accessed through the Defense Technical Information Center (DTIC) under accession number ADA509824.

12. References

• Hunter, D. R. (1995). Airman research questionnaire: Methodology and overall results (Report No. DOT/FAA/AM-95/27). Federal Aviation Administration Office of Aviation Medicine. https://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/1990s/media/AM95-27.pdf
• Hunter, D. R. (2002). Development of an aviation safety locus of control scale. Aviation, Space, and Environmental Medicine, 73(12), 1184–1188. https://pubmed.ncbi.nlm.nih.gov/12498546/
• Hunter, D. R. (2002). Risk perception and risk tolerance in aircraft pilots (Report No. DOT/FAA/AM-02/17). Federal Aviation Administration Office of Aerospace Medicine. https://doi.org/10.1037/e588402012-001
• Hunter, D. R. (2004). Measurement of hazardous attitudes among pilots. The International Journal of Aviation Psychology, 15(1), 23–43. https://doi.org/10.1207/s15327108ijap1501_2
• Hunter, D. R. (2006). Risk perception among general aviation pilots. The International Journal of Aviation Psychology, 16(2), 135–144. https://doi.org/10.1207/s15327108ijap1602_1
• Hunter, D. R., & Stewart, J. E. (2009). Locus of control, risk orientation, and decision making among U.S. Army aviators (Research Report 1912). United States Army Research Institute for the Behavioral and Social Sciences. https://apps.dtic.mil/sti/citations/ADA509824
• Jensen, R. S., & Benel, R. A. (1977). Judgment evaluation and instruction in civil pilot training (Report No. FAA-RD-78-24). Federal Aviation Administration.
• Reason, J. (1990). Human error. Cambridge University Press. https://doi.org/10.1017/CBO9781139062367

13. Items of the Scale