13.runway-incursion-prevention. Runway Incursion Avoidance
A runway incursion is defined by the FAA as any occurrence at an airport involving the incorrect presence of an aircraft, vehicle, or person on the protected area of a surface designated for the landing and takeoff of aircraft. Runway incursions threaten safety because they create the potential for a collision between aircraft, between aircraft and ground vehicles, or with personnel on the airport movement area. Pilots, controllers, and vehicle operators all share responsibility for prevention.
The FAA categorizes runway incursions by severity:
- Category A — A serious incident in which a collision was narrowly avoided.
- Category B — An incident in which separation decreases and there is significant potential for collision, possibly resulting in evasive action.
- Category C — An incident characterized by ample time and/or distance to avoid a collision.
- Category D — An incident that meets the definition of a runway incursion but with no immediate safety consequences.
Incursions are also classified by cause:
- Pilot Deviation (PD) — The pilot fails to comply with a regulation or ATC instruction (e.g., crossing a hold-short line without clearance).
- Operational Incident (OI) — A controller error, such as clearing two aircraft onto the same runway.
- Vehicle/Pedestrian Deviation (V/PD) — A vehicle, pedestrian, or unauthorized person enters the movement area without authorization.
Most incursions involve pilot deviations, and the majority occur during taxi at unfamiliar airports, in low-visibility conditions, or at night.
Airport Surface Markings and Signage. Preventing incursions begins with knowing the visual cues painted on the pavement and posted on signs.
- Runway Holding Position Markings: Four yellow lines (two solid, two dashed) painted across a taxiway. The solid lines are on the side from which the aircraft is approaching the runway. Never cross the solid side onto the runway without an explicit ATC clearance at a towered airport, or without confirming the runway is clear at a non-towered airport.
- Runway Hold Sign: A red square with white numerals (e.g., "15-33") posted alongside the holding position marking. This is a mandatory instruction sign.
- ILS Critical Area Holding Position Marking: Two yellow solid lines connected by pairs of perpendicular lines (a "ladder"). Hold here when so instructed to protect the ILS signal.
- Taxiway Location Sign: Black background with yellow letters; tells you where you are.
- Taxiway Direction Sign: Yellow background with black letters and arrows; shows where a taxiway leads.
- Surface-Painted Holding Position Signs: Red painted blocks with white numerals on the taxiway pavement, used to supplement the elevated sign.
ATC Clearances. A clearance to taxi to a runway authorizes you to cross all taxiways en route but does NOT authorize you to enter or cross any runway. To cross a runway, you must receive an explicit "cross runway XX" clearance. Likewise, takeoff requires "cleared for takeoff"; "line up and wait" authorizes you only to enter the runway and hold in position. Always read back, in full, any clearance that involves a runway crossing, hold short, takeoff, or landing — including the runway designator and your call sign.
Best Practices for Pilots.
- Plan the taxi before moving. Review the airport diagram (FAA Chart Supplement or 10-9 page), highlight your expected route, and identify hot spots.
- Use a current airport diagram in flight, especially at unfamiliar fields. The FAA publishes diagrams free at faa.gov.
- Hot Spots — Marked on airport diagrams with a brown circle or ellipse, these denote intersections with a history of collisions or confusion. Brief them prior to taxi.
- Sterile cockpit below 10,000 feet AGL and during all ground operations. Eliminate non-essential conversation while taxiing.
- Write down clearances. Use shorthand for taxi routes, hold-short instructions, and runway crossings.
- Read back all hold-short and runway crossing instructions verbatim, including the runway number.
- Stop and ask if you become disoriented. Request "progressive taxi" instructions from ground control.
- Scan before crossing any runway, even with a clearance. Look both directions for landing and departing traffic.
- Illuminate all exterior lights (taxi, landing, beacon, strobe per operator policy) when crossing or entering a runway, day or night, to enhance conspicuity.
- At night or in low visibility, taxi slower and verify position using signs, markings, and lighting (centerline green, edge blue).
Example. You are taxiing N123AB at an unfamiliar Class D airport. Ground states: "N123AB, taxi to runway 27 via Alpha, hold short of runway 33." Your readback: "Taxi to runway 27 via Alpha, hold short of runway 33, N123AB." Even though your destination is runway 27, you must stop at the hold-short line for runway 33 until cleared to cross. Crossing without that explicit "cross runway 33" clearance is a pilot deviation and a runway incursion.
Runway incursion avoidance is a discipline of preparation, communication, and vigilance — three habits that separate professional aviators from statistics in the NTSB database.