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Readbacks

ATC listens to your readback the way a controller does, and the window shows you the verdict.

What needs a readback

  • An IFR clearance or an amendment: all of its items.
  • Runway instructions: hold short, line up and wait, cleared for takeoff, cleared to land, and each runway crossing.
  • A taxi route's runway, and a hold short whenever it is for crossing a runway. A plain hold short of your departure runway is said but need not be read back, though a wrong runway is still corrected.
  • Altitudes, headings, crossing restrictions, procedures ("descend via"), and an approach clearance with its runway.

A frequency change needs no readback. "Over to Ground", "point seven", or just changing frequency are all fine.

A correct readback

Silence on the radio, as in real life, and a green ✓ Readback accepted in the window and the log. Only an IFR clearance, an amendment or a diversion clearance gets a spoken "readback correct". On a phone call, a correct readback of the clearance gets "readback correct, have a safe flight" and the call ends (for a clearance that holds for release, "readback correct, call back when you are number one").

A wrong readback

ATC corrects the one item that was wrong:

"Negative, squawk six six six two."

When only one item is in doubt, ATC may ask for that item by name: "confirm squawk, rest of readback correct". The correction is spoken firmly, with the wrong item stressed, after a short pause. The window shows an amber ✗ Corrected. A safety item you left out, such as a hold short or a runway, gets one "read back hold short instructions". ATC asks twice at most, then moves on with a "verify".

What it forgives

Speech recognition is not perfect, and neither is anyone's radio work:

  • Only a clearly different value is corrected. An item the recognition did not catch is not held against you, unless it is a safety item (a hold short, a runway, an altitude), which gets one "read back".
  • Names by sound. "Elma five" for the Elmaa Five arrival, "Helms six" for the Helns Six. The number has to be right.
  • Your callsign as you say it. A filed "WALKER 9798" is "Walker ninety-seven ninety-eight". A call with one character off, or with only the end of your registration, still counts as you. For an airline callsign filed in the New flight dialog, "Walker seventeen forty-five", "Walker one seven four five" and "Walker 1745" all count, but there is no short form: "Walker ninety-eight" alone gets "say again". ATC says a zero in a flight number as "zero" ("American ten zero four").
  • Numbers are strict. A different runway, altitude, heading or squawk is never accepted as close enough.

When you forget

About 30 seconds after ATC stops talking, and never while you are transmitting, ATC reminds you: "read back hold short instructions", "confirm cleared to land runway one six center". A takeoff clearance is reminded sooner.

The Read back line under push-to-talk shows what ATC is still waiting for, so you can see it before the reminder comes.

If ATC did not catch your callsign

A garbled call, or a first call to a position with no callsign, gets "Aircraft calling Seattle Ground, say again." It never gets a clearance. A readback without a callsign is fine.