AIM ¶ 2-1-4 — Runway Edge Lights
AIM 2-1-4 explains HIRL, MIRL, and LIRL runway edge lights, color coding, caution zones, and threshold/end lights for pilot students.
In Plain English
Runway edge lights outline the edges of a runway when it's dark or visibility is reduced. They come in three intensity classes:
- HIRL (High Intensity Runway Lights) — variable intensity
- MIRL (Medium Intensity Runway Lights) — variable intensity
- LIRL (Low Intensity Runway Lights) — typically a single intensity
The lights themselves are white, with two important exceptions you must know for checkride day:
- On instrument runways, the last 2,000 feet or half the runway length, whichever is less, is yellow. This forms a caution zone telling landing pilots they're running out of runway.
- The lights at the runway ends are bi-directional: they show red back toward the runway (warning departing aircraft of the runway end) and green outward (marking the threshold for arriving aircraft).
Operationally, recognizing these colors at night helps you confirm runway alignment, judge remaining landing distance, and avoid mistaking a taxiway or the wrong end of the runway for your touchdown zone.
AIM Source Text
FAA AIM ¶ 2-1-42-1-4. 2-1-4. Runway Edge Light Systems
Runway edge lights are used to outline the edges of runways during periods of darkness or restricted visibility conditions. These light systems are classified according to the intensity or brightness they are capable of producing: they are the High Intensity Runway Lights (HIRL), Medium Intensity Runway Lights (MIRL), and the Low Intensity Runway Lights (LIRL). The HIRL and MIRL systems have variable intensity controls, whereas the LIRLs normally have one intensity setting. The runway edge lights are white, except on instrument runways yellow replaces white on the last 2,000 feet or half the runway length, whichever is less, to form a caution zone for landings. The lights marking the ends of the runway emit red light toward the runway to indicate the end of runway to a departing aircraft and emit green outward from the runway end to indicate the threshold to landing aircraft.
Oral Exam Questions a DPE Might Ask
Q1What are the three classifications of runway edge light systems, and which have variable intensity?
Per AIM 2-1-4, runway edge lights are classified as High Intensity Runway Lights (HIRL), Medium Intensity Runway Lights (MIRL), and Low Intensity Runway Lights (LIRL). HIRL and MIRL have variable intensity controls; LIRLs normally have one intensity setting.
Q2What color are the runway edge lights, and when does that color change?
Per AIM 2-1-4, runway edge lights are white, except on instrument runways where yellow replaces white on the last 2,000 feet or half the runway length, whichever is less, forming a caution zone for landings.
Q3What do the red and green lights at the ends of a runway indicate?
Per AIM 2-1-4, the lights marking the ends of the runway emit red toward the runway to indicate the runway end to a departing aircraft, and emit green outward from the runway end to indicate the threshold to landing aircraft.
Related Paragraphs in AIM Chapter 2