Mandatory readbacks: what you must read back
Some ATC instructions can’t be answered with just “Roger” — you must repeat them back word-for-word so the controller knows you heard them correctly. Here is the standard list, and the difference between Roger, Wilco and a full readback.
The mandatory readback items
- Runway in use
- Altimeter settings (QNH / QFE) — add “hectopascals” when the QNH is below 1000
- Clearances to enter, land on, take off from, line up on, hold short of, cross or backtrack a runway
- Taxi instructions
- SSR (squawk) codes
- Level, heading and speed instructions
- Frequency changes
- Conditional clearances — repeat the condition and end with the condition word (e.g. “… behind the landing Cessna, behind”)
End the readback with your callsign. Information such as the wind, a readability report or traffic is acknowledged rather than read back.
Roger, Wilco — or a full readback?
Roger
“I have received all of your last transmission.”
Acknowledges information only. It does NOT mean you will comply, it is never used where a readback is required, and it is never the answer to a question — use “Affirm” or “Negative” for that.
Wilco
“Will comply” — I understand your message and will comply with it.
Use to acknowledge an instruction you will act on, e.g. after “report final” → “Wilco, G-ABCD.”
Report …
An instruction to tell the controller when you reach a point or condition, e.g. “report final”, “report field in sight”, “report downwind”.
Acknowledge it now — “Wilco, G-ABCD” (or read back the report point) — then actually make the report when you get there.
Readbacks are a habit, not a list
TowerTalk’s Exercise B drills readbacks against an AI controller with instant CAP 413-based feedback — free to try.
Related
Study aid, written in our own words from TowerTalk’s revision material (based on standard CAP 413 conventions). Last reviewed 3 July 2026; awaiting independent expert review. It does not reproduce CAP 413 and is not a substitute for it — always defer to CAP 413 and the current official publications, and to your instructor and examiner. TowerTalk is not CAA approved.