AIM Text
- 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.)
Source: FAA Aeronautical Information Manual · current edition · paragraph 2-1-1.
Research Notes
AIM 2-1-1 introduces Airport Lighting — visual aids for nighttime and low-visibility operations.
Major airport lighting components:
- Approach lighting systems (ALSF-I/II, MALSR, ODALS, REIL, SSALR)
- Runway edge lighting (HIRL/MIRL/LIRL)
- Runway threshold lighting
- Runway centerline lighting
- Touchdown zone lighting (TDZ)
- Taxiway centerline and edge lighting
- VASI / PAPI (visual glide slope)
- Airport beacon
Pilot-controllable lighting: At many GA airports, pilots can activate the lights via radio. Common: tune CTAF and click mic 5x for low, 7x for medium, 9x for high. Check the Chart Supplement for the specific airport.