Aids to Navigation Signal Flag Code

Examples of Aids to Navigation Signals


Two-letter signals for General Signal Code examples are listed below as they relate to aids to navigation. Single-letter signals should be allocated to significations which are very urgent, important, or of very common use. For web page layout purposes the signal flags are shown here horizontally. As a general rule only one hoist should be shown at a time. Each hoist or group of hoists should be kept flying until it has been answered by the receiving station. When more groups than one are shown on the same halyard they must be separated by a tackline. The transmitting station should always hoist the signal where it can be most easily seen by the receiving station, that is, in such a position that the flags will blow out clear and be free from smoke. A more complete list of two-letter codes is shown in Chapter 2, Section III of the International Code of Signals.

Two-letter signals for General Signal Code examples

Note: Two-letter codes use compliments. That’s basically a number that provides a variation of meaning within a certain group.

Code Meaning
LK Buoy (or beacon) has been established in lat… long…
LM Radiobeacon indicated is out of action.
LT Your bearing from me [or from… (name or identity signal)] is… (at the time indicated).
LV Let me know my bearings from you. I will flash searchlight.
LX The channel/canal/fairway is clear.
LY The channel/canal/fairway is not clear.
MD My course is.…
MD 1 What is your course?
MDSignal flag, One (1)
MJ Derelict dangerous to navigation reported in lat… long…
MM There is a wreck in lat… long…
MQ There is risk of contamination due to excessive release of radioactive material in this area (or in area around lat… long… ). Keep radio watch. Relay the message to vessels in your vicinity.
MY It is dangerous to stop.

MZ Navigation is dangerous in the area around lat… long…
ND Tsunami (phenomenal wave) is expected. You should take appropriate precautions.
VL Tropical storm (cyclone, hurricane, typhoon) is approaching. You should take appropriate
NE 5 You should proceed with great caution; hostile vessel sighted (in lat… long…).
NESignal flag, Five (5)
NH You are clear of all danger.
NK There is not sufficient depth of water.
OH You should switch on your radar and keep radar watch.
OS There is danger from mines in this area (or area indicated).
PD Your navigation light(s) is (are) not visible.
PH You should steer as indicated.
PS You should not come any closer.
PT 1 The tide is rising.
PTSignal flag, One (1)

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