What to Read Back to ATC

A readback is you repeating an instruction to the controller. The AIM calls it a double check between pilots and controllers, one that cuts the errors that happen when a number is misheard or wrong (AIM 4-4-7). It is not needed for everything ATC says. The AIM's word is “should”: its readback rules are guidance, not regulation. The one readback controllers are required to get from you is a hold short instruction (JO 7110.65 2-4-3).

What the AIM asks you to read back

In the air, read back the parts of a clearance or instruction that contain (AIM 4-4-7):

• Altitude assignments, including altitude restrictions: “descend and maintain two thousand five hundred”.
• Vectors: “turn left heading two seven zero”.
• Runway assignments: “runway two seven”.

Four rules from the same paragraph shape the readback:

1. Same order. Read altitudes, altitude restrictions and vectors back in the order you heard them.
2. Callsign every time. Include it in every readback and acknowledgment.
3. Charted altitudes stay out. Altitudes that are part of a published procedure, such as a departure procedure or an instrument approach, are not read back unless the controller says them.
4. Runway first time. Your first readback of a taxi, departure or landing clearance includes the runway, with left, right or center if there is one.

On the ground, the AIM adds: read back the runway assignment, any clearance to enter a specific runway, and any instruction to hold short of a runway or to line up and wait (AIM 4-3-18).

What the controller has to get from you

Controllers must make sure you acknowledge every clearance and instruction, check that what you read back is correct, and get a readback of every hold short instruction, whether it is part of a taxi clearance or a land and hold short clearance (JO 7110.65 2-4-3). Answer a runway hold short with “roger” and you will hear “read back hold instructions” (JO 7110.65 3-7-2).

Instruction by instruction

Controller says	You say	Why
Climb and maintain four thousand five hundred	Climb and maintain four thousand five hundred, (callsign)	Altitude assignment (AIM 4-4-7)
Turn right heading one eight zero	Right heading one eight zero, (callsign)	Vector (AIM 4-4-7)
Runway two seven, taxi via Alpha	Runway two seven via Alpha, (callsign)	Runway in the first readback of a taxi clearance (AIM 4-4-7)
Hold short of runway three six	Hold short of runway three six, (callsign)	Every runway hold short instruction (AIM 4-3-18, JO 7110.65 2-4-3)
Runway two seven, line up and wait	Runway two seven, line up and wait, (callsign)	Line up and wait (AIM 4-3-18)
Runway two seven, cleared for takeoff	Cleared for takeoff runway two seven, (callsign)	Runway in the readback of a departure clearance (AIM 4-4-7)
Runway two seven, cleared to land	Cleared to land runway two seven, (callsign)	Runway in the readback of a landing clearance (AIM 4-4-7)
Squawk four three five one	Squawk four three five one, (callsign)	Not on the AIM's list, but repeating the code catches a wrong digit
Contact Springfield Departure, one one niner point one	One one niner point one, (callsign)	Frequency changes must be acknowledged (AIM 4-2-3); the number checks you heard it right

What only needs an acknowledgment

• Traffic calls: answer “traffic in sight” or “negative contact” with your callsign.
• Information, such as a wind check or a pilot report: “roger” and your callsign. Roger means you received all of the last transmission (Pilot/Controller Glossary).
• Instructions with no numbers to repeat, such as “report midfield downwind”: “wilco” and your callsign. Wilco means you received the message, understand it and will comply (Pilot/Controller Glossary).

Roger only says you heard. It is not a yes or a no, and the glossary says not to use it to answer a yes-or-no question. For anything on the readback list, read it back instead.

How to give a clean readback

1. Write as you listen. Altitudes, headings, codes and frequencies go on the kneeboard as they come.
2. Keep the controller's order. The AIM asks for altitudes, altitude restrictions and vectors in the sequence they were given (AIM 4-4-7), and a readback in that order is easier to check.
3. Leave out the filler. The items and your callsign are enough. After first contact, the facility's name may be left out when the message needs an obvious reply and nothing could be misunderstood (AIM 4-2-3).
4. Put the callsign in the same place every time, at the start or at the end. The AIM allows either (AIM 4-2-3).
5. Listen to what comes back. If the controller corrects you, read back the corrected item.

When you cannot comply

Do not read back an instruction you cannot follow. Say “unable” instead, and say why if it helps: “unable, weather ahead”. Unable means you cannot comply with a specific instruction, request or clearance (Pilot/Controller Glossary), and accepting or refusing a clearance is your responsibility (AIM 4-4-7).

When you are not sure

Ask before you act. “Say again” gets the transmission repeated. “Verify” asks the controller to confirm something you are unsure of, as in “verify assigned altitude”. The AIM tells pilots to get clarification of any clearance or instruction they do not understand (AIM 4-3-18).

FAQ

Do I have to read back the whole taxi route?

The runway assignment, any clearance to enter a specific runway, and any instruction to hold short of a runway, yes (AIM 4-4-7, 4-3-18). The rest of the route is not on the list, but a readback of the whole route lets Ground catch a wrong turn before you make it. How to Call Ground for Taxi shows a full taxi readback.

Do I have to read back the altimeter setting?

It is not on the AIM's list. Repeating it costs a second and checks that you set the right number.

Is “wilco” enough for an altitude?

Not by the AIM's standard. A controller can accept “wilco” as an acknowledgment (JO 7110.65 2-4-3), but the AIM asks you to read back altitude assignments so the number gets checked (AIM 4-4-7).

What happens if I read back something wrong?

The controller is required to make sure your readback is correct (JO 7110.65 2-4-3), so expect a correction, and read the corrected item back. Controllers can miss a wrong readback, though: if a number does not sound right, ask, for example “verify assigned altitude”.

Do I read back hold short instructions from Tower too?

Yes. Read back every instruction to hold short of a runway, whoever gives it (AIM 4-3-18).