Roger, Wilco, Unable, Say Again: What They Mean

A handful of small words carry precise meanings on the radio. Use them right and you sound sharp; use them wrong — especially "Roger" — and you sound like a nervous beginner. Here is every one. · 6 min read

Aviation English packs a lot of meaning into a few short words, and each one means exactly one thing. The most common radio-vocabulary mistakes are not big errors — they are these tiny words used slightly wrong, and controllers notice instantly. The good news is there are only a handful, and once you know each one precisely, you will both sound more professional and, more importantly, communicate more clearly. Let us go through every one.

Roger

"Roger" means only one thing: "I received your last transmission." That is it. It does NOT mean "yes," and it does NOT mean "I will comply." This is the number-one radio-vocabulary error — pilots answer a yes/no question with "Roger," which tells the controller nothing. If Tower asks "do you have the traffic in sight?" the answer is "affirmative" or "negative," never "Roger."

Affirmative and Negative

These are your "yes" and "no." Use "affirmative" for yes and "negative" for no — they are distinct over a scratchy radio in a way that "yeah" and "nope" are not. "Skyhawk Five-Two-Kilo, do you have Information Bravo?" → "Affirmative, Five-Two-Kilo."

Wilco

"Wilco" is short for "will comply." Use it when you have received an instruction AND you will carry it out. It already implies you heard the message, so you almost never need "Roger, wilco" — just "wilco." Example: "Skyhawk Five-Two-Kilo, report a two-mile final." → "Wilco, Five-Two-Kilo."

Unable

"Unable" means "I cannot do that." It is one of the most important words a pilot has, and new pilots underuse it. Never go silent on an instruction you cannot safely follow — say "unable," and add a brief reason if it helps them re-plan: "Unable the climb to 8,000, Five-Two-Kilo, we can make 6,000." You are the pilot in command; "unable" is you exercising that authority safely.

Standby

"Standby" means "wait, I will get back to you" — used by both controllers and pilots. If you are heads-down and cannot answer a non-urgent call this second, "Five-Two-Kilo, standby" is perfectly fine. Just remember to come back to them.

Say again

"Say again" asks the other station to repeat their last transmission. Use it freely and without embarrassment — even airline crews say it constantly, and guessing at a garbled clearance is genuinely dangerous. You can also ask for just the part you missed: "say again the altitude." (Note: "I say again" is different — it prefaces a repeat of YOUR own transmission.)

Ident

"Ident" is an ACTION, not a word you transmit. When ATC says "squawk 0412, ident," you set the transponder code and press the physical IDENT button, which makes your target blink brightly on their radar so they can positively identify you. You read back the code ("squawk 0412, ident, Five-Two-Kilo") — but the ident itself is the button press, not something you say.

Traffic in sight / looking / negative contact

When ATC calls traffic to you, answer with whether you see it: "traffic in sight" (you see it), "looking" (searching), or "negative contact" (searching, do not have it yet). Only say "traffic in sight" when you genuinely see the specific aircraft — a false "in sight" can make ATC stop watching for you.

Phraseology sourced from the FAA Aeronautical Information Manual (Change 3, effective 9 July 2026) and the Pilot/Controller Glossary. Check the AIM · Last reviewed 13 August 2026.