Every year, runway incursions — events where an aircraft, vehicle, or person occupies a runway without authorization — rank among the most serious safety risks in aviation. Many of these incidents occur not on remote back-taxiways but in predictable, well-documented areas of the airport surface called hot spots. Learning what hot spots are, how to find them, and how to maintain situational awareness while taxiing is a cornerstone of safe airport operations and a regularly tested topic on the FAA Private Pilot Knowledge Test.
The FAA and airport operators work together to identify, chart, and publicize these danger zones so that every pilot — from a student on their first solo taxi to a seasoned ATP — arrives at each intersection fully prepared. This article walks through the definition and marking of hot spots, the broader discipline of surface movement situational awareness, and the practical habits that keep you and everyone around you safe on the ground.
What Is a Hot Spot?
A hot spot is a location on an airport's movement area that has a history of runway incursions or surface incidents, or that has the physical or operational characteristics that make such events more likely. The FAA defines them in the Aeronautical Information Manual (AIM) and publishes them on FAA/NACO airport diagrams (also called airport taxiway diagrams), which are available in digital and paper chart format. On those diagrams, hot spots appear as circled numbers printed in magenta (pink-red), with a corresponding legend that briefly describes the hazard at each location.
Hot spots are assigned a number unique to each airport — HS 1, HS 2, and so on. Some airports have only one; a large, complex airport may have a dozen or more. The written description in the legend might say something like: "HS 3 — Complex intersection; poor visibility of Runway 28L; hold short lines obscured in rain." This tells the pilot exactly what challenge to anticipate before they ever reach that point on the pavement.
Why Hot Spots Exist: The Root Causes
Hot spots exist because certain combinations of geometry, lighting, signage, and traffic flow make it easy for a pilot or vehicle operator to become confused or to inadvertently enter a runway. Common contributing factors include:
- Complex geometry: Intersections where multiple taxiways converge at unusual angles can make it difficult to tell which pavement leads onto a runway and which stays clear of it.
- Limited visibility: Buildings, terrain, taxiway curves, or the wing of a large aircraft can block a pilot's view of approaching traffic.
- Confusing or cluttered signage: Some older airports have sign placements that predate current standards; a pilot distracted by radio calls can miss a mandatory instruction sign.
- Unmarked or faded hold short markings: Weather wear can reduce the visibility of the double yellow hold short lines, especially during night or wet conditions.
- High traffic volume: More aircraft on the surface means more opportunities for simultaneous runway crossings.
- Parallel runways that share taxiways: Crossing one runway to reach a second is an environment where the clearance the tower gave you may expire faster than you expect.
Reading Hot Spots on Airport Diagrams
Whenever you plan a flight into or out of an airport you have not recently visited, pull up the current airport diagram — available through the FAA's digital Chart Supplement (formerly the Airport/Facility Directory) or an electronic flight bag application that sources official FAA data. Before you taxi, you should be able to answer three questions about each marked hot spot: Where exactly is it? What is the specific hazard? What extra action will I take when I reach it?
On the diagram itself, study the layout so the shape of the airport is familiar before you move an inch. Trace your expected taxi route with a finger or stylus and note every hot spot your route crosses or approaches. If the ATIS or ground controller gives you routing that differs from what you expected, pause and re-check before proceeding. Never be too rushed to verify your position.
Maintaining Surface Movement Situational Awareness
Hot-spot awareness is only one component of the broader discipline the FAA calls surface movement situational awareness — knowing exactly where you are, where the active runways are, and what clearances you have at all times while on the airport surface. The AIM dedicates an entire section to runway incursion avoidance (AIM Chapter 4, Section 3) and provides practical guidance pilots should internalize.
Cockpit Discipline During Taxi
Heads-down time in the cockpit — fiddling with avionics, studying charts, or programming a GPS — is one of the leading contributors to surface incidents. Accomplish as much cockpit setup as possible while parked at the ramp. Once you begin moving, keep your eyes outside the cockpit the vast majority of the time. If you must look inside, stop the aircraft first. This is not timid flying; it is disciplined flying.
Write down (or repeat back clearly) every taxi clearance. ATC is required to provide progressive taxi instructions to pilots who request them, and there is no shame in asking. If you are at an unfamiliar airport or the clearance was complex, a simple "Confirm routing, Cessna 123 Alpha" is far better than a wrong turn onto an active runway.
Sterile Cockpit on the Ground
While 14 CFR 121.542 mandates a sterile cockpit below 10,000 feet for air carriers, the same principle is wise for general aviation during critical ground phases. Avoid non-essential conversation and smartphone use while taxiing. If a passenger asks a question that requires a real answer, stop, answer, and then continue. The taxi phase is short; the conversation can wait.
Using Airport Markings and Lighting
The surface itself is full of information. Runway hold short markings consist of four yellow lines — two solid, two dashed — running perpendicular to the taxiway. The solid lines are always on the taxiway side; crossing them onto the runway side requires an explicit ATC clearance to enter or cross the runway. Runway guard lights (the flashing yellow "wig-wag" lights embedded in the pavement or elevated at runway entrances) are an additional cue that you are approaching a runway. At some airports, stop bar lights (a row of red in-pavement lights) are installed and must not be crossed when illuminated, regardless of any other instruction.
Signage follows a strict color code: red signs with white lettering are mandatory instruction signs (runway designations, "NO ENTRY"); yellow signs with black lettering or black signs with yellow lettering are informational (taxiway names, directions, distances). Knowing this code means you never have to guess whether a sign is telling you something optional or ordering you to stop.
Key Numbers and Rules
- Hot spots are shown in magenta on official FAA airport diagrams, with numbered callouts and a legend description.
- Hold short markings: four yellow lines (two solid toward the taxiway, two dashed toward the runway); the solid lines mark the boundary you may not cross without clearance.
- Runway guard lights flash yellow and mark runway entrances; stop bar lights are steady red and must not be crossed when illuminated.
- Read back runway crossing and hold short instructions: The AIM requires pilots to read back any instruction to hold short of a runway or to enter, cross, or backtrack on a runway. This is not optional courtesy — it is a required safety procedure.
- Land and Hold Short Operations (LAHSO): If you accept a LAHSO clearance, you accept responsibility for stopping before the designated hold short point. You may decline a LAHSO clearance without penalty, and student pilots should generally decline.
- The Chart Supplement (digital) provides written hot spot descriptions for each airport that has them; check this as part of preflight planning whenever visiting an unfamiliar field.
Memory Aid: TCAS for the Ground (The Taxi Flow)
A useful informal checklist some instructors teach for every runway approach during taxi is T-C-A-S — not the collision avoidance system, but a ground operations habit:
- T — Traffic: Look left and right down the runway for any aircraft on approach, landing rollout, or departing.
- C — Clearance: Confirm you have an explicit ATC clearance to cross or enter this specific runway, right now.
- A — ATIS/Advisory: Check that your understanding of the active runway configuration matches current ATIS. Runways can change.
- S — Signs and Markings: Verify the hold short line, the runway designation sign, and any guard lights before you cross.
Running through T-C-A-S takes less than ten seconds and can prevent a lifetime of regret.
Common Test Traps
- Hot spot color confusion: Hot spots are marked in magenta on airport diagrams, not yellow or red. Students sometimes confuse this with runway markings or restricted area shading on sectional charts.
- "Cleared for takeoff" ≠ clearance to cross a runway en route: A takeoff clearance from a different runway position does not authorize you to cross intervening runways. You need a separate crossing clearance for each runway.
- Readback requirements: The FAA test frequently asks which instructions require a readback. The answer: any hold short or runway entry/crossing instruction must be read back verbatim. Failure to do so is both a safety risk and a violation of AIM guidance.
- LAHSO student pilot restriction: The FAA strongly advises that student pilots not accept LAHSO clearances because they require precise rollout performance and familiarity with the airport layout. The test may ask who should decline LAHSO — the answer is student pilots (and pilots unfamiliar with their aircraft's performance in the conditions).
- Hot spots ≠ only runways: Some hot spots involve taxiway-to-taxiway geometry or areas near hangars with restricted sightlines. Do not assume every hot spot is a runway incursion point specifically — the hazard description in the legend tells you the full story.
Surface movement situational awareness is ultimately about intellectual humility and disciplined habit. The airport diagram, the ATC clearance, the painted lines, the lighted signs — all of these tools exist so you always know exactly where you are and where the hazards are. Use them every time, without exception, and the hot spots on the chart will remain nothing more than an annotated curiosity rather than a scene of a preventable incident.