Flashing light procedure: call, identity, text and ending
1The lesson in plain words
A flashing light signal has four parts: the call, the identity, the text and the ending. Short procedure signals keep both stations in step.
The call
To call a station whose identity you do not know, or all stations in sight, send the general call AA AA AA … until it answers. Otherwise call with its identity signal. The station called answers with the answering signal TTTT … and keeps it going until you stop calling.
The identity
You send DE, meaning ‘from’, then your identity signal or name. The receiver repeats it back, then sends her own identity, which you repeat back. Once two stations are already working, they may leave out the call and identity.
The text
The text is plain language or Code groups. Send YU before Code groups. The receiver acknowledges each word or group with T. AAA is a full stop or decimal point. AS asks the other station to wait, or separates groups. If you make an error, send the erase signal EEEEEE …; the receiver answers with the erase signal, and you repeat the last correct word and continue.
Repeats
RPT means “I repeat” when followed immediately by your repetition. Otherwise, as sender, it requests a readback: “Repeat what you have received”. As receiver, use RPT to request “Repeat what you have sent”. Add AA (all after), AB (all before), WA (word after), WB (word before) or BN (all between). For example, RPT AB KL means “Repeat all before KL”. Acknowledge a correct repetition with OK. For a received but unintelligible message, send ZL instead.
The ending
Send AR to end the signal or the transmission. The receiver answers R, ‘Received’. In the general call, join each AA pair without a letter gap. After RPT, AA means “all after”: send two separate A letters. Join AR, AS and AAA without letter gaps; keep normal gaps between their elements.
2Step by step
Exchanging a short message by lamp
- 1
Send AA AA AA … (or the station’s identity) until you see TTTT.
Nothing is read until the other station is watching.
- 2
Send DE and your identity; check it is repeated back, then repeat hers.
Both stations know exactly who is talking.
- 3
Send each word or group, waiting for T after each one.
T confirms receipt before you go on.
- 4
If you send a word or group incorrectly, send EEEEEE and wait for the receiver’s erase signal. Repeat the last correct word or group, then continue.
The receiver strikes out only the wrong part.
- 5
Finish with AR and wait for R.
R confirms the whole signal was received.
3Key data
- General call
- AA AA AA …; send each AA pair as one symbol
- Answering signal
- TTTT … until the caller stops
- Word or group received
- T
- Erase
- EEEEEE …, answered with the erase signal
- Ending / received
- AR answered by R
- Wait / group separator
- AS = wait or separate groups; AAA = full stop or decimal point
4Key points
- 1
Four parts: call (AA AA AA or identity), identity (DE …), text, ending (AR).
- 2
TTTT answers a call; T acknowledges each word or group; R acknowledges AR.
- 3
EEEEEE erases the last word; RPT with AA, AB, WA, WB or BN asks for a part again.
- 4
AS means wait; AAA is a full stop or decimal point; YU comes before Code groups.
5Frequent mistakes
Wrong: Start sending the text as soon as you think the other ship is looking.
Right: Wait for the answering signal TTTT. Until then nobody is reading.
Wrong: Answer the ending signal AR with T.
Right: T acknowledges a word or group. AR is answered with R, ‘Received’.
Wrong: Send RPT when a decoded group makes no sense.
Right: Use RPT to request repetition or a readback. If you received the signal but cannot understand its meaning, send ZL.
6Practice case & exam keys
You are sending ‘PILOT BOARDING DELAYED’ by lamp. After you send ‘BOARDING’ you realise you flashed ‘BORDING’. The receiver has already sent T. What do you do?
Show the answer
Send the erase signal, EEEEEE, and wait for her to answer with the erase signal. Then repeat the last word that was correct, ‘PILOT’, and continue: ‘BOARDING’, ‘DELAYED’, waiting for T after each word. Finish with AR and wait for R.
Exam keys
- General call AA AA AA; answering signal TTTT; identity with DE.
- T = word or group received; AR ending answered by R.
- Erase EEEEEE (answered likewise); RPT with AA/AB/WA/WB/BN; OK = correct repetition.
- AS wait; AAA full stop or decimal point; YU before Code groups.
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