4/20/23 

AIM 

Section 2.  Air Navigation and Obstruction Lighting 

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1.  Aeronautical Light Beacons 

a. 

An aeronautical light beacon is a visual NAVAID displaying flashes of white and/or colored light to indicate 

the location of an airport, a heliport, a landmark, a certain point of a Federal airway in mountainous terrain, or 

an obstruction. The light used may be a rotating beacon or one or more flashing lights. The flashing lights may 

be supplemented by steady burning lights of lesser intensity. 

b. 

The color or color combination displayed by a particular beacon and/or its auxiliary lights tell whether the 

beacon is indicating a landing place, landmark, point of the Federal airways, or an obstruction. Coded flashes 

of the auxiliary lights, if employed, further identify the beacon site. 

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2.  Code Beacons and Course Lights 

a.  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. 

b.  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. 

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Airway beacons are remnants of the “lighted” airways which antedated the present electronically equipped federal airways 

system. Only a few of these beacons exist today to mark airway segments in remote mountain areas. Flashes in Morse code 

identify the beacon site. 

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3.  Obstruction Lights 

a. 

Obstructions are marked/lighted to warn airmen of their presence during daytime and nighttime conditions. 

They may be marked/lighted in any of the following combinations: 

1.  Aviation Red Obstruction Lights. 

Flashing aviation red beacons (20 to 40 flashes per minute) and 

steady burning aviation red lights during nighttime operation. Aviation orange and white paint is used for daytime 

marking. 

2.  Medium Intensity Flashing White Obstruction Lights. 

Medium intensity flashing white obstruction 

lights may be used during daytime and twilight with automatically selected reduced intensity for nighttime 

operation. When this system is used on structures 500 feet (153m) AGL or less in height, other methods of 

marking and lighting the structure may be omitted. Aviation orange and white paint is always required for 

daytime marking on structures exceeding 500 feet (153m) AGL. This system is not normally installed on 

structures less than 200 feet (61m) AGL. 

3.  High Intensity White Obstruction Lights. 

Flashing high intensity white lights during daytime with 

reduced intensity for twilight and nighttime operation. When this type system is used, the marking of structures 

with red obstruction lights and aviation orange and white paint may be omitted. 

4.  Dual Lighting. 

A combination of flashing aviation red beacons and steady burning aviation red lights 

for nighttime operation and flashing high intensity white lights for daytime operation. Aviation orange and white 

paint may be omitted. 

5.  Catenary Lighting. 

Lighted markers are available for increased night conspicuity of high

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(69KV or higher) transmission line catenary wires. Lighted markers provide conspicuity both day and night. 

Air Navigation and Obstruction Lighting 

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