Runway Incursion Programs Need Severity-to-Closure Evidence, Not Counts Alone
Runway incursion counts are necessary aviation safety signals, but they are weak public evidence when presented alone. The same annual count can include low-consequence protected-area errors, serious near collisions, vehicle deviations, pilot deviations, controller operational incidents, geometry-driven hot spots, or events mitigated by local actions. This paper synthesizes FAA runway incursion definitions, public statistics, the 2024-2026 National Runway Safety Plan, the Runway Incursion Mitigation program, hot spot guidance, Runway Safety Action Teams, Runway Status Lights, the Surface Awareness Initiative, DOT OIG's 2025 audit, ICAO runway safety team guidance, and NASA ASRS reporting limits. The contribution is a count-to-closure accountability chain. A credible runway safety report should state the weakest verified stage: event count, severity, contributing type, location, geometry risk, awareness layer, mitigation action, technology layer, or recurrence closure.
Introduction
Runway incursions are rare relative to total operations, but their safety meaning is not captured by a single annual count. FAA defines a runway incursion as incorrect presence of an aircraft, vehicle or person on a protected runway surface [[cite:faaIncursionCategories]]. That definition correctly captures the boundary of the hazard, yet it says little about severity, causal type, geometry, technology layer or whether mitigation was closed.
This paper asks how airports and aviation regulators should report runway incursion mitigation without reducing safety performance to raw event counts. The answer proposed here is a count-to-closure accountability chain. It treats counting as the first surveillance step, not as the final safety claim.
The core argument is practical. A dashboard that reports fewer incursions may still hide a Category A near collision, a recurring hot spot, a nonstandard taxiway geometry, or an unresolved technology deployment. Conversely, a higher count may reflect better reporting or classification. Safety accountability therefore needs severity-to-closure evidence.
Methods
The study is a conceptual synthesis. Six AlexandrAI graph searches checked novelty. Twelve external searches targeted FAA definitions and statistics, national runway safety planning, hot spot and RIM guidance, DOT OIG audit evidence, runway safety teams, surface-safety technologies, ICAO guidance and NASA ASRS reporting limits.
Forty-three sources were screened, and seventeen were read deeply. Sources were included when they supplied one of six roles: severity definition, official count caveat, location/geometry mechanism, local mitigation process, technology layer, or reporting limitation. News reports and vendor technology claims were excluded when official sources were available.
ASRS was treated as qualitative evidence rather than a denominator. NASA describes ASRS as confidential, voluntary and non-punitive, while its runway-incursion report set warns that subjective voluntary reporting has quantitative limitations [[cite:nasaASRS,asrsReportSet]]. That distinction matters because mechanism discovery and rate estimation are different uses.
Background: severity changes the meaning of a count
FAA's category system is the starting point. Category D covers an incident with no immediate safety consequences; Category C has ample time or distance to avoid collision; Category B involves decreased separation and significant collision potential; Category A is a serious incident in which a collision was narrowly avoided; accident means a collision occurred [[cite:faaIncursionCategories]]. The category is not decoration. It changes the safety interpretation of the event.
FAA public statistics are necessary but explicitly provisional: the runway safety statistics page states that data are subject to revision [[cite:faaStats]]. A responsible public report should therefore disclose update date, category mix, operation denominator where available and whether records have changed.
Cause type also matters. FAA's close-call page reports CY2023 runway incursions as 60 percent pilot deviations, 20 percent operational incidents and 20 percent vehicle/pedestrian deviations [[cite:faaCloseCalls]]. Those percentages are not local root cause, but they show why a single count cannot tell an airport whether the next action is pilot outreach, controller procedure, vehicle control, geometry redesign or technology.
Results: a count-to-closure chain
The evidence supports a staged reporting model. The first stage is event detection and classification. The second is severity and type. The third is location: which runway, taxiway, crossing, hot spot or movement area produced the event. The fourth is mechanism: geometry, clearance, readback, signage, lighting, visibility, vehicle control or procedure. The fifth is mitigation: RSAT plan, RIM project, charted hot spot, training, technology, or procedural change. The final stage is recurrence closure.
RIM is the strongest geometry example. FAA says RIM identifies and mitigates nonstandard geometry factors at locations experiencing high numbers of runway incursions [[cite:faaRIM]]. The National Runway Safety Plan states that RIM analyzed and geo-referenced more than 16,000 runway incursion reports over 14 years [[cite:faaNRSP]]. The FY2024 RIM report describes a GIS database of approximately 520 towered civilian airports [[cite:faaRIM2024]].
Hot spots are an awareness stage. FAA publishes hot spot locations on airport diagrams, with descriptions in Chart Supplement material [[cite:faaHotspots]], and standardized symbology helps chart users recognize them [[cite:faaHotspotSymbology]]. ICAO similarly defines a hot spot as a location with history or potential risk where heightened attention is necessary [[cite:icaoRST]]. But a charted hot spot is not closure; it is a warning until mitigation reduces or removes the hazard.
Program design: local action and technology layers
Runway Safety Action Teams are the local governance layer. FAA says RSATs bring local airport stakeholders together at least annually to identify surface-safety risks and develop mitigation plans [[cite:faaRSAT]]. ICAO's Runway Safety Team Handbook supports the same local, collaborative logic [[cite:icaoRST]]. A public report should therefore show which event clusters became action items and which action items closed.
Technology should be reported as a layer, not as a slogan. FAA describes Runway Status Lights as a fully automatic advisory system designed to reduce the number and severity of incursions and prevent accidents [[cite:faaRWSL]]. FAA describes the Surface Awareness Initiative as improving controller situational awareness and addressing the challenge of seeing all surface activity [[cite:faaSAI]]. These are different functions and should be linked to the hazard stage they address.
The DOT OIG audit supplies the caution. It found that FAA had taken steps but still had work to do on data analytics and implementation of key initiatives, focusing especially on Category A and B incursions at primary commercial airports since FY2022 [[cite:dotOig2025]]. That audit supports a closure-oriented ledger rather than a purely narrative progress report.
Minimum public reporting fields
A count-to-closure report requires fields that preserve context after aggregation. At minimum, each record should retain event date, airport, operation context, severity category, contributing type, surface location, hot-spot flag, geometry note, local action owner, mitigation status, technology layer and post-action recurrence check. Without those fields, the public can see that something happened but not whether the safety system learned from it.
The severity field should be mandatory because the same word, incursion, spans Category D through accident. A program that reports total incursions without category mix may look worse after improved detection or look better while a rare Category A event appears. Severity-weighted reporting does not replace counts; it makes counts interpretable [[cite:faaIncursionCategories,faaStats]].
The location field should be spatial enough to support geometry work. FAA's RIM program and annual summary show why location matters: recurring events at a taxiway/runway intersection can indicate nonstandard geometry, signage, hold-short placement, sightline or pilot-driver path complexity [[cite:faaRIM,faaRIM2024]]. A public map need not expose sensitive operational details, but the internal ledger must be spatial.
The action-owner field should separate awareness from mitigation. A hot spot on a diagram is an awareness intervention; an RSAT item is a governance intervention; a RIM project is an engineering intervention; Runway Status Lights or SAI are technology interventions. Reporting them as one generic response obscures whether the remaining risk is human, procedural, geometric or technological [[cite:faaHotspots,faaRSAT,faaRWSL,faaSAI]].
The closure field should describe what happened after the response. Closure may mean chart revision completed, training delivered, procedure changed, geometry modified, technology commissioned, or post-action recurrence checked for a defined period. If no recurrence window exists, the report should say the action is implemented but not yet outcome-verified.
These fields also protect against false precision. If a local airport has only count and severity, the report should stop there. If it has event narratives but no closure check, it should claim risk diagnosis rather than mitigation. If it has completed geometry work but too little post-action exposure time, it should claim implementation, not demonstrated recurrence reduction.
Discussion
The proposed chain changes how a runway safety dashboard should be read. A falling count without category mix, operation denominator and data revision status is weak evidence. A severity-weighted location map is stronger. A map that links hot spots, geometry studies, RSAT actions, RIM projects and post-action recurrence is stronger still.
The model also handles contradictory data sources. FAA counts are official but revised; ASRS narratives are rich but voluntary; hot spot diagrams improve attention but do not prove elimination; RWSL and SAI are powerful but airport-specific layers [[cite:faaStats,asrsReportSet,faaHotspots,faaRWSL,faaSAI]]. A good report uses each source for the claim it can support.
Serious events deserve special visibility, but lower-severity events should not vanish. DOT OIG focused on Category A and B events because they represent serious collision potential [[cite:dotOig2025]]. Yet Category C and D events can be precursors when they cluster at a location or repeat a mechanism. The chain therefore keeps severity and recurrence together rather than choosing one.
Finally, mitigation should be reported with ownership. Pilot deviations, operational incidents and vehicle/pedestrian deviations point to different owners, even when all occur at the same intersection. The public ledger should connect each mechanism to a responsible forum: flight standards, air traffic, airport operations, RSAT, RIM engineering, charting or technology deployment.
Limitations
This paper does not compute new runway incursion rates or audit individual airport projects. It synthesizes official public materials into a reporting model. Local validation would require airport operation counts, incident narratives, geometry files, RSAT minutes, project records, technology status and post-action trend analysis.
The model also does not claim that every mitigation effect is quickly observable. Serious incursions are rare, traffic mix changes, reporting improves and data are revised. That is why the paper emphasizes staged evidence and caveats instead of a single before-after count.
Conclusion
Runway incursion programs should publish more than counts. Counts start the safety conversation, but the safety claim depends on severity, type, location, mechanism, mitigation owner, technology layer and recurrence closure. A count-to-closure chain makes those distinctions explicit.
The practical recommendation is to report the weakest verified stage. If only a count is known, say so. If severity and location are known, publish that. If RSAT or RIM actions are assigned, show status. If geometry, charting, procedure or technology mitigations are complete, show post-action recurrence. The strongest runway safety report is not the one with the smallest number; it is the one that can explain what changed at the places where risk was highest.