AIM Text
- Airport and heliport beacons have a vertical light distribution to make them most effective from one to ten degrees above the horizon; however, they can be seen well above and below this peak spread. The beacon may be an omnidirectional capacitor-discharge device, or it may rotate at a constant speed which produces the visual effect of flashes at regular intervals. Flashes may be one or two colors alternately. The total number of flashes are:
- 24 to 30 per minute for beacons marking airports, landmarks, and points on Federal airways.
- 30 to 45 per minute for beacons marking heliports.
- The colors and color combinations of beacons are:
- White and Green- Lighted land airport.
- *Green alone- Lighted land airport.
- White and Yellow- Lighted water airport.
- *Yellow alone- Lighted water airport.
- Green, Yellow, and White- Lighted heliport.
- Military airport beacons flash alternately white and green, but are differentiated from civil beacons by dualpeaked (two quick) white flashes between the green flashes.
- In Class B, Class C, Class D and Class E surface areas, operation of the airport beacon during the hours of daylight often indicates that the ground visibility is less than 3 miles and/or the ceiling is less than 1,000 feet. ATC clearance in accordance with 14 CFR part 91 is required for landing, takeoff and flight in the traffic pattern. Pilots should not rely solely on the operation of the airport beacon to indicate if weather conditions are IFR or VFR. At some locations with operating control towers, ATC personnel turn the beacon on or off when controls are in the tower. At many airports the airport beacon is turned on by a photoelectric cell or time clocks and ATC personnel cannot control them. There is no regulatory requirement for daylight operation and it is the pilot's responsibility to comply with proper preflight planning as required by 14 CFR section 91.103.
Source: FAA Aeronautical Information Manual · current edition · paragraph 2-1-9.
The short answer
This AIM section is FAA advisory guidance on airport and heliport beacons, describing their flash rates (24 to 30 per minute for airports, 30 to 45 for heliports) and color codes. Daytime beacon operation in Class B, C, D, and E surface areas often signals weather below VFR, but pilots must still comply with preflight planning required by 14 CFR 91.103.
Research Notes
Common Questions
What do the airport beacon colors mean?
White and green, or green alone, indicates a lighted land airport. White and yellow, or yellow alone, indicates a lighted water airport. Green, yellow, and white indicates a lighted heliport. Military airport beacons flash alternately white and green but add dual-peaked (two quick) white flashes between the green flashes.
Does a beacon operating in daylight mean the weather is IFR?
In Class B, C, D, and E surface areas, daytime operation of the airport beacon often indicates ground visibility less than 3 miles and/or a ceiling less than 1,000 feet, requiring ATC clearance under 14 CFR part 91. However, pilots should not rely solely on the beacon, since at many airports it is switched by a photoelectric cell or time clock that ATC cannot control.
How fast do airport versus heliport beacons flash?
The total number of flashes is 24 to 30 per minute for beacons marking airports, landmarks, and points on Federal airways, and 30 to 45 per minute for beacons marking heliports. The beacons have a vertical light distribution most effective from one to ten degrees above the horizon.