Signals
| Sample Single Letter Messages | ||
| Flag Hoist | Code | Meaning |
|---|---|---|
| A | I have a diver down; keep well clear at slow speed. | |
| B | I am carrying, loading or discharging dangerous goods. | |
| H | I have a pilot on board. | |
Prior to 1969, the Code was much more extensive, covering a wider range of messages and included a list of five-letter codes for every prominent maritime location in the world. Since 1969, it has been reduced to focus on navigation and safety, including a medical section. Signals can be sorted into three groups:
- Single-letter signals which are very urgent, important, or common.
- Two-letter signals for other messages, sometimes followed with a numeric "complement" that supplements or modifies the message.
- Three-letter signals beginning with "M" – these are the Medical Signal Codes.
In some cases, additional characters are added to indicate quantities, bearing, course, distance, date, time, latitude, or longitude. There is also provision for spelling words and for indicating use of other codes. Several of the more common single-letter signals are shown at the right. Two-letter signals cover a broad gamut of situations; the interested reader is urged to download a copy of the Code from the link below.
Repeated characters can be a problem in flaghoist. To avoid having to carry multiple sets of signal flags, the Code uses three "substitute" (or "repeater") flags. These repeat the flag at the indicated position. For instance, to signal MAA ("I request urgent medical advice", see diagram below) the Mike, Alfa, and 2nd substitute flags would be flown, the substitute indicating a repeat of the second character.
Read more about this topic: International Code Of Signals
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