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Learning hub · Communications · Lesson 2

IFR radio phraseology: clearances, approaches and holding

When you fly under instrument flight rules, air traffic control (ATC) and you share a plan. The radio is how that plan is agreed, changed and checked. This lesson shows how a clearance is built, what you must read back, and what to do if you cannot do what you are asked.

About 13 minutes, plus the quiz. Part of Communications. It builds on VFR radio phraseology.

1. What a clearance is made of

An ATC clearance is an authorisation for an aircraft to proceed under conditions that ATC specifies. It is not an order to do something, it is permission to do something within limits. A full IFR clearance normally contains these parts, in a fixed order, so that you can follow it like a checklist:

  1. the call sign;
  2. the clearance limit, the point to which you are cleared, often the destination aerodrome;
  3. the route, which may be your filed route, or a standard departure route;
  4. the level, which may be an initial level with a later level to expect;
  5. other necessary items: the transponder code, departure instructions, communication details, or the time the clearance expires.

An invented example: “Zulu Zulu Alfa Bravo Charlie, cleared to Hillcrest airport, Dolby one alpha departure, climb to altitude four thousand feet, squawk four three two one.” Here, Hillcrest is the clearance limit, the departure is the route, 4,000 feet is the level and the code follows. Everything here is invented, including the departure name.

Do not climb above the cleared level or leave the route because the clearance seemed to give you more. A clearance gives you exactly what it says. If a part is missing or unclear, ask. Ask before you move, since a question on the radio is cheap and a wrong turn in cloud is not.

2. Readback requirements

Readback is a safety net. The controller hears what you understood and can correct it. The standard requires you to read back the safety-critical items. Always read back:

  • ATC route clearances;
  • instructions to enter, land on, take off from, hold short of, cross, taxi on or backtrack on a runway;
  • the runway in use, altimeter settings and transponder codes;
  • level, heading and speed instructions, and newly assigned frequencies;
  • the transition level, if it is given to you.

The readback ends with your call sign. If you read back wrongly, the controller will say “negative” and give the correct version, and you must read that back as well. If you did not understand, say “say again” instead of guessing. Other clearances and instructions must still be read back or acknowledged so that it is clear you understood and will comply. Information such as the wind or a traffic report can be acknowledged with your call sign alone. Some states and units ask for more, so check your AIP.

3. Clearance or instruction?

The two are close in everyday speech, but they differ in meaning, and that matters when you disagree or cannot comply.

  • A clearance is permission to do something within stated limits: “cleared to land runway two seven”, “cleared ILS approach runway two seven”, “cleared direct to the Dolby VOR”. You are free to act, but only within the limits you have been given.
  • An instruction is a direction to take a specific action: “turn left heading two seven zero”, “reduce speed to one six zero knots”, “hold short of runway two seven”, “contact Hillcrest Approach one two five decimal five”. You carry them out promptly, so that the controller’s picture of the traffic stays true.

Because a clearance expires or is limited, you must be sure what you hold. The most common mistake is to take an instruction for a clearance, or the reverse. “Hold short” means you do not cross the line. “Cleared to land” means you may land. A controller who does not say you may land has not given you permission, even if the runway looks free.

4. Approach and holding

On an approach you will hear a short chain of phrases. Typical examples, again with invented names:

  • “Descend to altitude three thousand feet, QNH one zero one four.” (a level instruction with an altimeter setting, both read back)
  • “Turn right heading one eight zero, report established on the localiser.”
  • “Cleared ILS approach runway three six.” (the clearance to fly the published procedure)
  • “Contact Hillcrest Tower one one eight decimal two.” (an instruction to change frequency)

The words “cleared for the approach” allow you to follow the published procedure, including its altitudes, from the point where the clearance applies. If you need to fly a missed approach, you say “going around” and follow the published missed approach unless ATC gives something else.

Holding. A hold is a racetrack pattern that keeps you at a fixed place and level while you wait. When you are told to hold, the instruction normally gives the fix, the level, the inbound track or the published pattern, the direction of the turns (right turns unless told to turn left), the leg time if it is not standard, and the time at which you can expect further clearance. For example: “Hold at the Dolby VOR, as published, expect further clearance at one four three five.” You read it back. The expected further clearance time matters for your planning, for example your fuel. What you do in a hold if radio fails is set by national rules: ICAO procedures work from the expected approach time you last acknowledged, while some states, such as the USA, use the expected further clearance time. Check the AIP.

What to do if radio contact is lost is set out in national rules and in the clearance you hold. As a general idea, you squawk 7600, continue according to your current clearance and flight plan, and follow the published procedure to reach and fly an approach. The details, such as how long you wait before leaving a hold or whether you may leave controlled airspace, are national. Study the AIP for the state you fly in before your first IFR flight there.

5. When you cannot comply

Sometimes you cannot do what you have been asked. The cause may be weather, an aircraft problem, your own limits, or an instruction that you think would put you at risk. The pilot in command has the final authority for the safety of the aircraft. The rule is simple: tell ATC early, say clearly what you cannot do, and say what you can do instead.

  1. Say “Unable” followed by what you cannot do. Do not say only “negative”.
  2. Give the reason in a few words if it helps, for example “unable, weather” or “unable, aircraft limitation”.
  3. Say what you request: “request heading two nine zero to avoid the cloud”, or “request a different level”.
  4. Wait for the new clearance and read it back. Do not take the new route before you have it.

If you must depart from a clearance in an emergency and cannot ask first, do what is needed to keep the aircraft safe, tell ATC as soon as you can, and ask for an amended clearance. Use PAN PAN or MAYDAY if the situation calls for it.

This lesson is for training. For a real flight, use the phraseology in the AIP and the procedures given by ATC, your operator and the aircraft flight manual. Never rely on an invented example, such as the names here, in real flying.

6. Try it yourself

Work each one out on paper first, then open the answer to compare. The numbers are invented.

  1. All names here are invented. ATC says: “Zulu Zulu Alfa Bravo Charlie, cleared to Hillcrest airport, Dolby two alpha departure, climb to altitude three thousand feet, squawk two zero four five.” Pick out the clearance limit, the route, the level and the code, and write your readback.
    Show the answer

    Clearance limit: Hillcrest airport. Route: Dolby two alpha departure. Level: altitude three thousand feet. Transponder code: two zero four five.

    Readback (route clearances, levels and transponder codes must all be read back, ending with your call sign): “Cleared to Hillcrest airport, Dolby two alpha departure, climb to altitude three thousand feet, squawk two zero four five, Zulu Zulu Alfa Bravo Charlie.”

    Do not climb above 3,000 ft or leave the route because the clearance seemed to give you more. If a part is unclear, ask before you move.

  2. Say whether each phrase is a clearance or an instruction, and what you must do with it: (a) “cleared ILS approach runway three six”; (b) “turn left heading two seven zero”; (c) “hold short of runway two seven”; (d) “contact Hillcrest Tower one one eight decimal two”; (e) “cleared direct to the Dolby VOR”.
    Show the answer

    A clearance is permission to do something within stated limits: (a) and (e). You are free to act, but only within those limits. (a) lets you fly the published procedure, including its altitudes.

    An instruction is a direction to take a specific action, which you carry out promptly: (b), (c) and (d).

    All five should be read back or acknowledged. Heading instructions, runway hold-short instructions and newly assigned frequencies are on the read-back list. “Hold short” means you do not cross the line, and “cleared to land” is the only thing that means you may land.

  3. ATC says: “Zulu Zulu Alfa Bravo Charlie, climb to altitude six thousand feet.” Because of the weather you judge that you cannot accept that level safely. What do you say, and what happens next?
    Show the answer

    The pilot in command has the final authority for the safety of the aircraft. Tell ATC early, say clearly what you cannot do, and say what you can do instead.

    For example: “Unable six thousand feet, weather, request altitude four thousand feet, Zulu Zulu Alfa Bravo Charlie.” Say “unable” and not only “negative”.

    Then wait for the new clearance and read it back. Do not climb or change level before you have it. If you had to depart from a clearance in an emergency without time to ask, keep the aircraft safe, tell ATC as soon as you can, ask for an amended clearance, and use PAN PAN or MAYDAY if the situation calls for it.

7. Watch

Practice with IFR clearances and readback. It is American, so wording and some rules differ from European (ICAO/EASA) practice, but the structure of the clearance and the habit of readback are the same.

Open on YouTube if the player does not load. Not made by VectorEFB; check what you learn against your flying school’s material and your instructor.

More to watch

A practical look at how to copy and understand an IFR clearance. This video is American, so wording and some rules differ from European (ICAO/EASA) practice, but the structure of a clearance and the habit of readback are the same.

Open on YouTube if the player does not load. Not made by VectorEFB.

8. Check yourself

Five original practice questions. Answer them, press Check answers and read each explanation.

1. Which of these is an ATC instruction rather than a clearance?

An instruction directs a specific action, such as a heading. The others give permission within limits.

2. Which item belongs in a full IFR clearance?

A clearance contains the call sign, the clearance limit, the route, the level and other items such as the transponder code.

3. ATC gives you a heading and an altimeter setting. What should you do?

Heading instructions and altimeter settings are among the items that must be read back.

4. You cannot accept a level that ATC gives you because of icing. What do you say first?

Say “unable”, give the reason and ask for what you need. Then wait for a new clearance.

5. What does the time in “expect further clearance at one four three five” give you?

It is the time you can expect the next clearance. It also helps you plan fuel. What to do if radio fails is set by the national rules.

Back to the learning hub.

For training and situational awareness only. Not certified for navigation. Always use official charts, the AIP, NOTAMs and a proper weather briefing for real flights.