Meaning: “I have received all of your last transmission.” It indicates that your message was received, but it does not indicate agreement or compliance.
Usage: Use “Roger” when you have heard and understood what was said, but there is no need to take any action or you have already complied with the instruction.
Example: If ATC says, “Cessna 123AB, wind 320 at 10,” a pilot might respond, “Roger, Cessna 123AB,” acknowledging the information has been received.
Affirm:
Meaning: “Yes” or “That is correct.” It’s used to confirm information or answer in the affirmative.
Usage: Use “Affirm” to clearly agree with a question or confirm information.
Example: If ATC asks, “Cessna 123AB, can you accept a heading of 270 degrees?” the pilot would reply, “Affirm,” if they can comply.
Wilco:
Meaning: “I will comply.” It’s a promise that you will carry out a given instruction.
Usage: Use “Wilco” when you are agreeing to perform a future action.
Example: If ATC says, “Cessna 123AB, after landing, roll to the end of the runway,” the pilot might respond, “Wilco, Cessna 123AB,” indicating they will follow the instruction.
Negative:
Meaning: “No” or “That is not correct.”
Usage: Use “Negative” to disagree or give a negative response.
Example: If ATC asks, “Cessna 123AB, are you equipped with GPS?” and you are not, respond with, “Negative, Cessna 123AB.”
Unable:
Meaning: Indicates that you cannot comply with a specific instruction due to operational limitations or safety concerns.
Usage: Use “Unable” when you’re not able to follow an ATC instruction.
Example: If ATC instructs, “Cessna 123AB, climb to 10,000 feet,” and you cannot due to aircraft performance, you would respond, “Unable, Cessna 123AB.”
Say Again:
Meaning: A request to repeat the last transmission.
Usage: Use “Say Again” if you did not understand or hear the previous transmission.
Example: “Say Again, Cessna 123AB.”
Readback:
Meaning: Repeating back instructions to confirm understanding.
Usage: Use readback for clearances and critical instructions to ensure accuracy.
Example: “Cleared to land Runway 22, Cessna 123AB.”
