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Taking a UK Flight Radio Telephony Operator Licence course and have fallen into a rabbithole.

From CAP 413 edition 23 (the CAA's Radiotelephony Manual):

2.48
The placement of the callsigns of both the aircraft and the ground station within an established RTF exchange should be as follows:

2.49
Ground to Air:

  • Aircraft callsign – message or reply.

Air to Ground:

  1. Initiation of new information/request etc. – Aircraft callsign then message
  2. Reply – Repeat of pertinent information/readback/acknowledgement then aircraft callsign.

So an exchange started by the ATCO begins and ends with the aircraft callsign:

G-ABCD, runway two seven, cleared for take-off.

Runway two seven, cleared for take-off, G-ABCD

However there are counterexamples in the manual:

5.4 (page 161 in the PDF):

G-CD, report heading.

G-CD, heading three five zero.

G-CD, for identification turn left heading three two zero degrees.

5.9, one of the examples:

BIGJET 347, confirm transponder operating.

BIGJET 347, negative, transponder unserviceable.

5.25:

G-CD, traffic 11 o'clock, ...

G-CD, traffic in sight

Followed by numerous examples of "[Callsign], Roger". There's more of those in reply to an AFIS in figure 43 (PDF page 352).

Are these just inaccuracies in the manual? I spotted a couple of definite typos so it's not impossible. Or are they holdovers from a previous standard? Or, are there situations where the pilot should begin their reply with their callsign?

(Beyond the QDM procedures where the pilot starts and ends their transmission with their callsign, presumably to give more time for a fix to be taken.)

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  • $\begingroup$ Welcome to aviation.SE! This seems like a dupe of this question, although perhaps yours is more specific. $\endgroup$
    – Pondlife
    Feb 9, 2022 at 0:56
  • $\begingroup$ Cheers @Pondlife, I did see that question, but that one is not specific to any country and the accepted answer quotes section 2.49 which is where I was starting from. $\endgroup$
    – Jack Deeth
    Feb 9, 2022 at 1:11
  • $\begingroup$ That's a very good analysis! If I were you I would contact the CAA to clarify any doubt for you and the public (me included!) $\endgroup$
    – Afe
    Feb 9, 2022 at 17:43

1 Answer 1

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The important word in 2.49 is "repeat". The callsign comes at the end of the transmission when the pilot is repeating information from ATC - in the example from 4.28, the pilot is repeating the takeoff clearance, so ends the transmission with the callsign.

In all other examples, the pilot is providing new information (the altitude, transponder status, etc) to ATC, so begins the transmission with the callsign.

[Callsign], Wilco is not a valid transmission, and does not appear anywhere (that I can find) in the current version (June 2020) of CAP 413. [Callsign], Roger is a valid transmission - the pilot is informing ATC that the transmission has been received and understood.

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  • $\begingroup$ 2.49.2 is "repeat of pertinent information, or readback, or acknowledgement" surely? You don't repeat an acknowledgement. I think I was mistaken about "[callsign] Wilco" but why would that be invalid and "[callsign] Roger" valid? $\endgroup$
    – Jack Deeth
    Feb 9, 2022 at 1:07
  • $\begingroup$ @JackDeeth Yes, that could be an alternative parsing of the sentence - put the callsign at the end if the transmission is either (a) a repeat of information, (b) a readback, or (c) an acknowledgement. The result is the same - the transmissions which provide new information to ATC do not come into one of those three categories, so start with the callsign. $\endgroup$
    – Tevildo
    Feb 9, 2022 at 8:33
  • $\begingroup$ @JackDeeth For "Roger" and "Wilco", "Wilco" is an acknowledgement, so the callsign goes at the end, "Roger" is telling ATC something they didn't know (that you have received and understood their transmission), so the callsign goes at the beginning. $\endgroup$
    – Tevildo
    Feb 9, 2022 at 8:43
  • $\begingroup$ However, CAP 413 generally does state "Roger, [Callsign]" too… $\endgroup$
    – Jack Deeth
    Feb 9, 2022 at 11:31

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