AIM Text
- Code Beacons. The code beacon, which can be seen from all directions, is used to identify airports and landmarks. The code beacon flashes the three or four character airport identifier in International Morse Code six to eight times per minute. Green flashes are displayed for land airports while yellow flashes indicate water airports.
- Course Lights. The course light, which can be seen clearly from only one direction, is used only with rotating beacons of the Federal Airway System: two course lights, back to back, direct coded flashing beams of light in either direction along the course of airway.
Source: FAA Aeronautical Information Manual · current edition · paragraph 2-2-2.
The short answer
This AIM section is FAA advisory guidance on code beacons and course lights. Code beacons flash a three- or four-character airport identifier in International Morse Code six to eight times per minute, green for land airports and yellow for water. Course lights, seen from one direction, mark Federal Airway System rotating beacons; only a few remain in remote mountain areas.
Research Notes
Common Questions
What does a green versus yellow code beacon flash mean?
The code beacon flashes the three or four character airport identifier in International Morse Code six to eight times per minute. Green flashes are displayed for land airports while yellow flashes indicate water airports. The beacon can be seen from all directions.
What is a course light and where are they still found?
A course light can be seen clearly from only one direction and is used only with rotating beacons of the Federal Airway System; two course lights back to back direct coded flashing beams along the airway course. These airway beacons are remnants of the lighted airways, and only a few exist today in remote mountain areas.
How is an airway beacon site identified to a pilot?
Flashes in Morse code identify the beacon site. These few remaining airway beacons mark airway segments in remote mountain areas and antedate the present electronically equipped federal airways system.