Outside of the approach, runway, and taxiway lights you've already encountered, there are a few other distinguishing lights commonly found on and around airports at night or in periods of low visibility. These include the airport beacon, helipad lighting, and obstruction lighting around the airport.
The airport beacon is a light signal used to identify not only where the airport is during times of low visibility or darkness, but also to identify the type of use of the airport. Beacons differentiate between public use airports, water/seaports, heliports, and military air bases.
In general, airport beacons operate from sunset to sunrise, and operate during the day only when the visibility is below 3 statute miles and ceilings are below 1,000 feet (when the airport is classified as IFR). Keep in mind though that this may not always be the case and a thorough weather briefing should still be conducted before each flight to determine the meteorological conditions at the airport.
Airport versus Heliport
A beacon indicating an airport will flash 24 to 30 times per minute, while a beacon lighting a heliport will flash 30 to 45 times per minute. While an airport will flash green and white or yellow and white, a heliport beacon will flash yellow, green, and white at intervals each minute.
Airport versus Seaport
White and Green: land airport
White and Yellow: sea airport
Green, Yellow, and White: heliport
Public Use versus Military
Like a public use airport, military airport beacons flash white and green. A military airport beacon, however, has a dual-peaked (two flashes in quick succession) white flash between the green flashes.
There are 5 main types of obstruction lighting used to warn aircraft of both natural and man-made obstacles that penetrate up to a level where aircraft could be present. These obstacles will be lighted at all hours, day and night.
Obstruction lighting can be classified as red obstruction lights, medium intensity flashing white lights, high intensity white lights, dual lights, and catenary lighting.
- Red lights can be flashing or steady burning and can be used in conjunction with paint to warn aircraft of the obstruction during the day.
- Medium and high intensity white lights are often used across chasms or on catenary wires to warn aircraft of otherwise invisible hazards such as guide wires, powerlines, and catenary lines.
- Dual lights are a combination of steady burning as well as flashing red obstacle lights used during the night and flashing high intensity white lights during daylight hours.
- Catenary lighting is used to improve visibility of high voltage transmission lines such as catenary lines and are used during the day and night.
Airport helipad lights are green to distinguish them from fixed wing aircraft areas. Helipad lighting is activated through the same controls as the runway, taxiway, and approach lighting systems.