LIGHT FLASH CHARACTERS.  All lighted aids to navigation, with the exception of those aids equipped with fixed (continuous) lighting, follow an established light flash character pattern. Such characters describe the periodic rhythm of a navigation light, thus enabling it to be identified on charts or while in visual contact.

A light flash character may be expressed as a series of letters and numbers which describe the operating characteristics of a particular light. The following provides an example of such a character as it might appear in the List of Lights or any other Coast Guard publication:


In all cases, the first letter(s) in the light flash character gives reference to the general light flash type or classification. This classification is based on the duration of illumination in relation to eclipse (darkness) for each light flash. In the example on page 20, the letter β€œQ” indicates that the aid is equipped with a quick flashing light; a quick flashing light being one which flashes at a rate of one flash per second.

Where a light exhibits group flashes, the second symbol in the character will indicate the number of flashes in each grouping. In the same example, the β€˜β€˜(6)’’ indicates that flashes occur in groups of 6. Where the aid exhibits a single, ungrouped flash no value will be shown.

Any additional flash that may be included in the sequence will be indicated by the use of a β€˜β€˜+’’ in the character followed by reference to an additional flash or flash grouping. For example, in the illustration on page 20, the quick (Q) six flash grouping (6) is followed by a long flash (+LFl).

The final number in the light flash character identifies the period of time within which the entire flash sequence occurs, as shown in the example on page 20. The character indicates that the entire flash sequence will be repeated every 15 seconds or 4 times every minute.

Once the entire light flash character is taken into account, the mariner should be able to correctly identify the aid (e.g. the example shows a light flash character for a South Cardinal buoy). 

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