Marking Oil & Gas structures - IALA G1162

Published on Friday, 06 May of 2022

IALA has created a recommendation for the correct marking of man-made offshore structures, including oil & gas platforms to aid to vessels navigation.

Each of the platforms shall be marked as a single unit, a block or field, which simplifies the marking process.


• Morse letter “U” every 15 secs

• Light colour white visible in any direction

• Intensity range 10 nm

• Vertical divergence 2.5º

• Constructed and fixed as to ensure that at least one light is visible upon approaching the structure from any direction.



• Flashing red light

• Morse letter “U” every 15 secs

• Intensity range 3 nm

• They shall be located at the horizontal ends of the structure and at interconnecting bridges



• Visible in all directions

• Black letters or numbers 1m high on a yellow background.


These are the main aids to navigation, in addition to which ATON may be included:


• Autonomy 96h for a power source independent

• Morse letter “U” every 30 secs

• Sound range 2 nm in any direction (MAIN)

• Minimum sound range 1/2 nm in any direction (SECONDARY)

• A visibility detector will typically be used


• Frequency range*

– X band: 9,300 – 9,500 MHz

– S band: 2,900 – 3,100 MHz.

• Broadcasting uniformity: ±2 dB in X+S bands over 360° (horizontal).*

• Vertical divergence: ±3 dB in bands X+S / 15° (vertical).*

* ITU-R M.824-4 standard


In the following drawing we can see how to place the aids to navigation on an offshore platform:

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