FRTOL01What CAP 413 Is
CAP 413 is the UK Radiotelephony Manual, published by the Civil Aviation Authority. It sets out the words, phrases and call formats that UK pilots, controllers, flight information officers and air/ground radio operators are expected to use. The current version is edition 24, effective from 1 July 2026.
It matters to you for two reasons. It's what your FRTOL practical test is marked against, and it's what you'll hear from every UK ground station. CAP 413 also notes that the Communications theory exam for pilot licences is drawn from ICAO material (Annex 10 and Doc 9432) rather than from CAP 413 itself. Our FRTOL written exam guide covers that paper.
How It Differs from ICAO
CAP 413 is built on the international (ICAO) standards, but the UK has notified a set of differences where it thinks the ICAO version could be misunderstood here. CAP 413 lists them in its Appendix 1. The ones a student is most likely to meet:
- Flight levels in whole hundreds are "flight level one hundred", not "one zero zero", to avoid confusion with adjacent levels, such as "one zero zero" misheard as "one one zero".
- Contact means your details have already been passed to the next unit. Freecall means they haven't, so you'll need to give them in full.
- Recleared is only used for routes, never for climbs or descents.
- You can put the aircraft make, model or category in front of your callsign, such as "Cessna Golf Echo Romeo".
- Solo student pilots may put "Student" in front of their callsign. (Separately, CAP 413 asks you to include your pilot qualifications in an emergency call whenever possible.)
Abroad, use ICAO phraseology plus that country's own differences.
02Standard Words and Phrases
These words have fixed meanings on the radio. Use them exactly, and use plain language only when no standard phrase fits.
| Word or phrase | What it means |
|---|---|
| Acknowledge | Tell me you've received and understood this. |
| Affirm | Yes. (Not "affirmative".) |
| Approved | Permission granted for what you proposed. |
| Break | Separates one part of a message from the next. |
| Cancel | The clearance just given is withdrawn. |
| Check | Examine a system or procedure. No reply is normally expected. |
| Cleared | Authorised to go ahead, under the conditions stated. |
| Confirm | Please verify (a clearance, instruction, action or piece of information). |
| Contact | Call this unit; they already have your details. |
| Correct | That's right. |
| Correction | I made a mistake; here's the right version. |
| Disregard | Ignore that. |
| How do you read | How clearly can you hear me? |
| I say again | I'm repeating this, for clarity or emphasis. |
| Monitor | Listen out on the frequency given. |
| Negative | No; or permission refused; or that's wrong; or I can't. |
| Pass your message | Go ahead with your details. |
| Read back | Repeat all, or the part I name, back to me exactly. |
| Report | Tell me the following. |
| Request | I'd like to know, or I'd like to have. |
| Roger | I've received your last transmission. Nothing more. |
| Say again | Repeat all, or part, of what you just said. |
| Speak slower | Slow down. |
| Standby | Wait, and I'll call you back. It is neither a yes nor a no. |
| Unable | I can't comply, usually followed by why. |
| Wilco | Understood, and I will comply ("will comply"). |
Some words are only used by certain ground stations. An air/ground radio operator (callsign "Radio") doesn't say "approved" or "report", and neither "Radio" nor a flight information officer ("Information") says "cleared", "climb" or "descend", because they don't give clearances. Hearing one of those words tells you you're talking to air traffic control.
For how numbers inside these phrases are spoken, see our aviation phonetic alphabet and numbers guide.
03Roger, Wilco, Affirm and Negative
These four are the most misused words on the frequency.
- Roger says only that the message arrived. It doesn't say you agree, understood or will do anything. Use it to acknowledge information, such as traffic or weather: "Roger, Golf Echo Romeo".
- Wilco says you've understood an instruction and will carry it out. "Report overhead" gets "Wilco, Golf Echo Romeo". Never say "roger wilco": wilco already includes roger.
- Affirm and negative are yes and no. Because roger only means "received", it is never the answer to a question that needs a yes or no. If the controller asks "confirm you are VFR", the answer is "Affirm, Golf Echo Romeo".
- Neither roger nor wilco replaces a read-back. If the message contains a safety item from the list below, you read that item back.
04What You Must Read Back
CAP 413 lists the messages you read back in full, because a misunderstanding could be serious. Always finish with your callsign. Anything not on the list can be acknowledged more briefly.
- Taxi instructions
- Level instructions
- Heading instructions
- Speed instructions
- Airways or route clearances
- Approach clearances
- The runway in use
- Clearances to enter, land on, take off from, backtrack, cross or hold short of an active runway
- SSR (transponder) instructions
- Altimeter settings, with units below 1000 hPa
- VDF information
- Frequency changes
- The type of ATS service
- Transition levels
Information, such as surface wind or traffic, isn't read back. If you read something back wrongly, the controller says "negative" and gives the correct version, and you read it back again. There's a worked example in our read-back guide.
05How a Call Is Built
On first contact, use the full callsign of the station and your own, then say what you want. Keep it short and let the ground station invite the details.
- Who you're calling"Gloster Approach"
- Who you are"Golf Juliett Juliett Echo Romeo"
- What you want"request Basic Service"
When the reply is "pass your message", give your details in this order, whenever possible:
- Callsign and aircraft type
- Departure point and destination
- Present position
- Level
- Additional details or intentionsFlight rules, next route point.
Our initial call guide walks through it with examples. Wait at least 10 seconds before calling a second time, and only shorten your callsign once the ground station has done so.
06Worked Example Calls
These use the made-up registration G-JJER and "Gloster" as the ground station. They show the shape of each exchange, not the real procedures, frequencies or reporting points of any aerodrome.
Taxi
Gloster Ground, Golf Juliett Juliett Echo Romeo, PA-28 at the flying club, request taxi for a VFR flight to Oxford, information Bravo.
Golf Echo Romeo, taxi holding point Alpha One, runway two seven, QNH one zero one fife.
Taxi holding point Alpha One, runway two seven, QNH one zero one fife, Golf Echo Romeo.
Taxi instruction, runway and QNH are all on the read-back list. The controller shortened the callsign first, so you can too.
Take-Off
Golf Echo Romeo, ready for departure.
Golf Echo Romeo, runway two seven, cleared for take-off, surface wind two fower zero degrees one zero knots.
Runway two seven, cleared for take-off, Golf Echo Romeo.
Say "ready for departure", never "ready for take-off": the words "take-off" are only used in the clearance itself (or when cancelling one). The wind is information, so it isn't read back.
A FIS Call to London Information
London Information, Golf Juliett Juliett Echo Romeo, request Basic Service.
Golf Juliett Juliett Echo Romeo, London Information, pass your message.
Golf Juliett Juliett Echo Romeo, PA-28, from Gloster to Oxford, one zero miles east of Gloster, altitude two thousand fife hundred feet, Cotswold one zero one tree, VFR, tracking to Oxford.
Golf Echo Romeo, Basic Service, Cotswold one zero one tree.
Basic Service, Cotswold one zero one tree, Golf Echo Romeo.
The service and the pressure setting are both read back. A flight information officer gives information, not instructions, so you won't hear "cleared" from "Information".
A Zone Transit Request
Wrayton Radar, Golf Juliett Juliett Echo Romeo, request zone transit.
Golf Juliett Juliett Echo Romeo, Wrayton Radar, pass your message.
Golf Juliett Juliett Echo Romeo, PA-28, from Newbridge to Gloster, fife miles south of Wrayton, altitude two thousand feet, QNH one zero one fife, VFR, request transit of the zone northbound.
Golf Echo Romeo, squawk fower fower two one.
Squawk fower fower two one, Golf Echo Romeo.
Golf Echo Romeo, cleared to cross the zone northbound, VFR, not above altitude two thousand feet, QNH one zero one fife.
Cleared to cross the zone northbound, VFR, not above altitude two thousand feet, QNH one zero one fife, Golf Echo Romeo.
Until you hear "cleared", you're not cleared to enter. A clearance is read back word for word.
Joining Overhead
Gloster Tower, Golf Juliett Juliett Echo Romeo, request join.
Golf Juliett Juliett Echo Romeo, Gloster Tower, pass your message.
Golf Juliett Juliett Echo Romeo, PA28, one zero miles south-east, altitude two thousand fife hundred feet, VFR, request join.
Golf Echo Romeo, join overhead, runway two seven, left-hand circuit, QFE one zero zero niner.
Join overhead, runway two seven, left-hand, QFE one zero zero niner, Golf Echo Romeo.
Golf Echo Romeo, overhead, descending deadside.
Golf Echo Romeo, report downwind.
Wilco, Golf Echo Romeo.
In a standard overhead join you cross the aerodrome 2,000 ft above its elevation, descend on the dead side to circuit height, cross the upwind end and position downwind. Check beforehand whether the aerodrome has its own joining procedure.
A Pan Call
PAN PAN, PAN PAN, PAN PAN, Gloster Approach, Student Golf Juliett Juliett Echo Romeo, PA-28, rough running engine, intend to land at Gloster, eight miles south of Gloster, altitude two thousand feet, heading three six zero degrees, student pilot, one person on board.
Student Golf Juliett Juliett Echo Romeo, Gloster Approach, roger PAN, squawk seven seven zero zero.
Squawk seven seven zero zero, Student Golf Juliett Juliett Echo Romeo.
The order is: PAN PAN three times, station, callsign (with "Student" if you're solo), type, the problem, your intentions, position, level and heading, your qualifications, then anything else useful. See Mayday and Pan for the full list.
07Common Mistakes
- Answering a question with "roger". Use affirm or negative.
- "Roger" instead of a read-back. Safety items are read back in full, every time.
- Forgetting your callsign at the end of a read-back.
- Shortening your callsign first. Wait for the ground station.
- "Ready for take-off". Say "ready for departure".
- "Affirmative" or "copy". Neither is standard. Say affirm, or roger.
- Saying "over" and "out". They're not normally used on VHF.
- Packing too much into the first call. Callsigns and request first, details when asked.
- Hesitating. Plan the call, then press the switch. Avoid "er", and don't release the switch until you've finished.
08Frequently Asked Questions
What is CAP 413?
The UK Radiotelephony Manual, published by the CAA. It sets the standard UK phraseology and is what the FRTOL practical test is marked against. The current version is edition 24, effective 1 July 2026.
What's the difference between roger and wilco?
Roger means "received". Wilco means "understood, and I'll do it". Neither replaces a read-back, and roger never answers a yes/no question.
Is CAP 413 the same as ICAO phraseology?
Mostly. The UK has notified some differences, such as "flight level one hundred", the meanings of contact and freecall, and pilot qualifications in emergency calls. Abroad, use ICAO phraseology.
What must I read back?
Clearances, runway instructions, taxi, level, heading and speed instructions, squawks, altimeter settings, frequency changes, the type of service and a few more, always ending with your callsign.
Do I say over and out?
Not normally. CAP 413 notes they aren't normally used on VHF, which is what light aircraft use.
This guide and the FRTOL app aren't approved by or affiliated with the UK CAA, and they don't replace your instructor or the official documents. Example calls are illustrative. Checked against CAP 413 (edition 24, effective 1 July 2026) in November 2026.