ATC Clearance Prefix

AIM ¶ 4-4-2 — ATC Clearance Prefix

AIM 4-4-2 explains the 'ATC clears,' 'ATC advises,' and 'ATC requests' prefixes used when clearances are relayed through air-to-ground stations.

In Plain English

AIM 4-4-2 describes the standard prefixes used when an ATC clearance, control instruction, or information response is relayed to you by a third party — typically an air-to-ground communication station such as an FSS — rather than spoken directly by the controller.

When a non-ATC station passes ATC information to you, the message will begin with one of three prefixes:

"ATC clears" — used when relaying an actual clearance (for example, an IFR departure clearance).
"ATC advises" — used when relaying control information or advisories.
"ATC requests" — used when ATC is asking the pilot to do something or provide information.

Why it matters operationally: at airports without a control tower, or when you can't reach Center directly, you may pick up your IFR clearance through Flight Service. The prefix is your cue that the words came from ATC, not the relaying station. Read back the clearance as you would any other to confirm accuracy.

This is informational guidance, not a regulation, but it reflects standard phraseology you should recognize on a checkride.

AIM Source Text

FAA AIM ¶ 4-4-2

4-4-2. 4-4-2. Clearance Prefix A clearance, control information, or a response to a request for information originated by an ATC facility and relayed to the pilot through an air-to-ground communication station will be prefixed by “ATC clears,” “ATC advises,” or “ATC requests.”

Oral Exam Questions a DPE Might Ask

Q1If you pick up an IFR clearance through Flight Service, what prefix tells you the message originated from ATC?

Per AIM 4-4-2, the relayed message will be prefixed with "ATC clears," "ATC advises," or "ATC requests," depending on whether it's a clearance, control information, or a request.

Q2What is the difference between "ATC clears" and "ATC advises"?

Per AIM 4-4-2, "ATC clears" precedes an actual clearance issued by ATC, while "ATC advises" precedes control information or an advisory being relayed through an air-to-ground station.

Q3Why are these specific prefixes used when a clearance is relayed by a station like FSS?

Per AIM 4-4-2, the prefixes identify that the clearance, control information, or request was originated by an ATC facility and is being relayed to the pilot through an air-to-ground communication station, distinguishing it from information from the relaying station itself.

Related Paragraphs in AIM Chapter 4

¶ 4-4-1

ATC Clearance

¶ 4-4-10

Adherence to ATC Clearance

¶ 4-4-11

IFR Separation Standards

¶ 4-4-12

ATC Speed Adjustments

¶ 4-4-13

Runway Separation

¶ 4-4-14