How to read back a taxi clearance in Canada, word for word

We are holding the brakes in the run-up bay with the engine warm and the checklist done, and Ground has just read us a taxi clearance. We caught the runway. We think we caught the taxiway. There was something after it about holding short, and a number that was probably the altimeter, and it all arrived in one breath. Our thumb is on the mic, and the honest truth is that the readback we are about to give is a version of a clearance we are not sure we heard.

Every one of us has been exactly there. A taxi clearance sounds like a fast run of numbers and letters the first dozen times you hear one, and the instinct is to read back whatever you can salvage and start rolling. But a taxi clearance is not a run-on sentence. It is a short list with a fixed shape, and once you can hear the shape you can catch the whole thing — and read it back, word for word, the way it is meant to come back.

What a taxi clearance is actually made of

Before you ever key up you listen to the ATIS and note its letter, so that your first call to Ground can end with "with information Charlie" — telling the controller you already have the current runway, wind and altimeter, and they need not read it all to you.^[1] On the way in it goes further than good practice: arrivals are required to monitor the ATIS before contacting the tower.^[4]

Then Ground answers with the clearance, and it is built from the same parts almost every time:^[1]

• Your call sign — so you know the clearance is for you and not the aeroplane behind you.
• The runway in use, and usually the wind and altimeter setting — though if you already checked the ATIS letter in, the altimeter may be all that comes back.
• The taxi route — which taxiways to follow to get there ("taxi via Bravo").
• A hold-short instruction — where to stop short of a runway and wait.
• Often a frequency change — "contact Tower" on a stated frequency when you reach the hold.

Hear those slots and the clearance stops being a blur. You are no longer trying to memorise a sentence; you are filling in a form whose shape you already know.

The clearance, word for word

Here is a full exchange at a towered field. Our aeroplane is a Cessna 172, registration C-GKWL — on the radio, the last four characters with the Canadian "C" dropped: "Golf Kilo Whiskey Lima."^[1]

You: "Springbank Ground, Cessna 172 Golf Kilo Whiskey Lima, at the north apron, with information Delta, VFR to the practice area."

Ground: "Cessna 172 Golf Kilo Whiskey Lima, Springbank Ground, runway 25, altimeter three zero one two, taxi via Bravo, hold short runway 25."

You: "Runway 25, altimeter three zero one two, taxi Bravo, hold short runway 25, Golf Kilo Whiskey Lima."

Now the readback, slot by slot:

• "Runway 25" — you repeat the assigned runway, so any mix-up between 25 and, say, 07 surfaces now rather than at the hold line.^[1]
• "altimeter three zero one two" — an altimeter setting is one of the safety-of-flight numbers worth reading back, so the controller can catch a digit you copied wrong.^[1]
• "taxi Bravo" — the route. You do not have to parrot "taxi via"; the taxiway letter is the load-bearing part.
• "hold short runway 25" — the one part that is not optional. More on that in a moment.
• "Golf Kilo Whiskey Lima" — your call sign, on the end of the transmission, because that is how the controller knows the readback came from the right aeroplane.^[1]

Notice what the readback is for. It is not a courtesy. In Canada a readback of a clearance is how you accept it, and it is the controller's chance to hear their own instruction come back and catch an error before you act on it.^[4][3]

What you must read back — and what you only should

As a VFR pilot you are not required to read back every transmission a controller sends you; a good deal of ordinary traffic can be acknowledged with your call sign alone.^[3][1] The things worth reading back in full are the ones that keep aeroplanes apart: the runway, the altimeter, the taxi route, and any clearance to enter or cross a runway.^[1]

One item, though, is a hard rule rather than good practice. A hold-short instruction must be read back — the words "hold short," the runway, and your call sign — every single time.^[1][3] A bare "roger" will not do, and neither will your call sign on its own. The hold-short words themselves have to come back out of your mouth, because that readback is the controller's confirmation that you know exactly where you are stopping.^[1]

A taxi clearance is not a clearance onto a runway

This is the distinction that catches people, and it is worth being blunt about. A taxi clearance authorises you to move along taxiways. It does not authorise you to set a wheel on a runway — not to cross one, not to line up on one.^[1] At a controlled aerodrome you need a clearance from ATC — Ground for the taxi itself — and separate clearances again to enter a runway, to take off, or to land.^[2][1]

So if your route to the runway crosses another runway on the way, "taxi via Bravo" is not permission to roll across it. You taxi up to that runway, you hold, and you wait for the specific words — "cross runway 33" — and then you read those back too before you move:^[1]

Ground: "Golf Kilo Whiskey Lima, cross runway 33, taxi via Bravo, hold short runway 25."

You: "Cross runway 33, taxi Bravo, hold short runway 25, Golf Kilo Whiskey Lima."

Crossing any runway needs a clearance to do it, and that clearance gets read back like every other runway instruction.^[1] The safe default is simple: if nobody has said the word "cross," you do not cross.

If you don't know the field, say so

None of this assumes you have the airport diagram memorised. If you are new to an aerodrome, or the taxiways are complex, or the visibility is poor, you can ask for a progressive taxi — the controller breaks the route into short, manageable legs and gives them to you one at a time instead of in a single string.^[1] Flag it early: adding "unfamiliar" to your first call tells the controller to give you simpler routing and to keep a closer eye on you.^[1] Neither is an admission of weakness. Both are how a careful pilot handles an unfamiliar surface, and a controller would far rather route you slowly than watch you guess.

The three that bite students

Almost every taxi-clearance mistake is one of three, and all three are avoidable.

Reading back a garble. If the clearance went by too fast, do not read back a hopeful reconstruction of it. Say "say again," and copy it clean the second time.^[1] A confident readback of the wrong clearance is worse than no readback, because it tells the controller you understood when you did not.

Dropping the hold-short. It is easy, in a long clearance, to read back the runway and the route and let the hold-short fall off the end. That is the one part you are never allowed to drop.^[1][3] If you can only get one thing right in a taxi readback, get the hold-short.

Crossing a runway on a taxi clearance. A "taxi to" instruction is not a "cross." Treating taxi authorisation as blanket permission to cross the runways in your path is exactly how a runway incursion begins.^[2][1] Hold short, wait for the crossing clearance, read it back, then move.

The whole thing, made dull

A good taxi readback is unremarkable: the same slots, in the same order, with the hold-short always on the list and the crossing clearance never assumed. The gap that reading and memorising never quite close is the clearance that arrives at real pace, from a real controller, while the aeroplane is running and the checklist is still half-done in your lap. You can know the shape cold and still fumble the first one that is for keeps.

None of it is hard to say. The work is wearing the grooves deep enough that the readback runs on its own — so the first time a clearance comes at you for real, the only thing new about it is that the seat beside you is empty.