AIM ¶ 2-1-1 — Approach Light Systems
AIM 2-1-1 explains Approach Light Systems (ALS): how they help pilots transition from instrument to visual flight for landing. Study guide for checkride prep.
In Plain English
Approach Light Systems (ALS) are the runway lighting configurations that help you transition from instrument flight to visual flight during the final stages of an approach. When you break out of the clouds near minimums, the ALS gives you the visual cues needed to identify the runway environment and continue to landing.
Key facts from AIM 2-1-1:
- ALS start at the landing threshold and extend outward into the approach area.
- For precision instrument runways, ALS extend 2,400–3,000 feet from the threshold.
- For nonprecision instrument runways, ALS extend 1,400–1,500 feet from the threshold.
- The sophistication and configuration of the system depends on the operational requirements of that particular runway.
- Some ALS include sequenced flashing lights (often called "the rabbit") that appear as a ball of light racing toward the runway twice per second.
Why this matters operationally: under 14 CFR 91.175, identifying the approach light system is one of the visual references that allows you to descend below DA/MDA, so understanding ALS is critical for safe, legal IFR landings.
AIM Source Text
FAA AIM ¶ 2-1-12-1-1. 2-1-1. Approach Light Systems (ALS)
ALS provide the basic means to transition from instrument flight to visual flight for landing. Operational requirements dictate the sophistication and configuration of the approach light system for a particular runway. ALS are a configuration of signal lights starting at the landing threshold and extending into the approach area a distance of 2400-3000 feet for precision instrument runways and 1400-1500 feet for nonprecision instrument runways. Some systems include sequenced flashing lights which appear to the pilot as a ball of light traveling towards the runway at high speed (twice a second). (See FIG 2-1-1 .)
Oral Exam Questions a DPE Might Ask
Q1What is the primary purpose of an Approach Light System (ALS)?
Per AIM 2-1-1, ALS provide the basic means to transition from instrument flight to visual flight for landing.
Q2How far do approach light systems typically extend from the landing threshold for precision versus nonprecision runways?
Per AIM 2-1-1, ALS extend 2,400–3,000 feet into the approach area for precision instrument runways and 1,400–1,500 feet for nonprecision instrument runways.
Q3What are sequenced flashing lights, and how do they appear to the pilot?
Per AIM 2-1-1, sequenced flashing lights are included in some ALS and appear to the pilot as a ball of light traveling toward the runway at high speed, flashing twice per second.
Related Paragraphs in AIM Chapter 2