The Aviation Phonetic Alphabet, Alfa to Zulu

The Full Alphabet

These are the words, pronunciations and Morse code from AIM table 4-2-7. The pronunciations are the FAA's capitalized respellings. Two letters have two accepted pronunciations: Charlie and Uniform.

How Pilots Say Numbers

The same AIM table gives each digit its own pronunciation. Three, five and nine look odd on the page, and each has a reason.

ICAO's history page, discussing Annex 10, Volume II, says three is pronounced as "tree," five as "fife" and nine as "niner." Wikipedia gives the reasons for two of them: "fife" helps keep five distinct from "fire," and the extra syllable in "niner" keeps it distinct from the German word "nein."

Zero is spoken as "zero" in the FAA table, and a number such as 10 is spoken digit by digit as "one zero."

When Pilots Use It

The AIM gives three situations, in paragraph 4-2-7:

• Poor reception. FAA personnel use the ICAO alphabet when conditions are such that the information can't be readily received without it.
• Similar call signs. ATC facilities may ask pilots to use phonetic letters when aircraft with similar-sounding identifications are on the same frequency.
• First contact. Pilots should use it when they identify their aircraft during initial contact with ATC facilities. They should also use it for single letters and to spell out groups of letters or difficult words in adverse communications conditions.

Your Call Sign

Paragraph 4-2-4 of the AIM sets the form for a US registration. A civil pilot states the aircraft type, model or manufacturer's name, then the digits and letters of the registration. When the type or manufacturer is stated, the N is dropped. The AIM's own examples are "Aztec Two Four Six Four Alpha" and "Bonanza Six Five Five Golf." The AIM text spells Alfa as "Alpha" in these examples, and the pronunciation is the same.

The AIM adds three more rules:

• Call signs should never be abbreviated on an initial contact, or at any time when other call signs have similar numbers or sounds.
• ATC may abbreviate a civil call sign to the prefix and the last three digits or letters once communication is established, and the pilot may then do the same.
• Air taxi and other commercial operators without FAA-authorized call signs put the phonetic word "Tango" in front of their identification, as in "Tango Aztec Two Four Six Four Alpha."

Airlines use their authorized call sign with the number in group form, and add "heavy" or "super" where it applies. The AIM's examples are "United Twenty-Five Heavy" and "Midwest Commuter Seven Eleven." If a pilot has any doubt about a clearance, the AIM gives the phrase "Verify clearance for" followed by the complete call sign.

ATIS Letters

The Automatic Terminal Information Service, ATIS, is a continuous recorded broadcast of weather and airport information. Each recording carries a phonetic letter, and the AIM tells pilots to say that letter back on first contact. Its example is "Information Sierra received."

The AIM says ATIS is updated on receipt of any official hourly or special weather report, and a new recording is also made when other pertinent data changes, such as the runway in use. The letter tells a controller which version of the broadcast you have. See our guide to aviation radio communication for the rest of a typical exchange.

Numbers Beyond the Digits

Several more AIM paragraphs, 4-2-8 to 4-2-12, set how other numbers and times are spoken. The examples below are the AIM's own.

The AIM notes that ICAO procedures speak the decimal point as "decimal," and the FAA honors that for military aircraft and anyone else required to use ICAO procedures. The AIM also says "Zulu" may be used for UTC, the same Z that ends a time in a weather report. Our guide to reading a METAR shows where it appears.

How the Alphabet Came About

Before today's list, civil aviation used an alphabet developed for joint operations in the Second World War, called Able/Baker after its first two words. ICAO's own history page says its Communications Division adopted that alphabet in 1946.

The next steps come from ICAO's history page. In 1947 the airline association IATA put forward a draft for a single universal alphabet. During 1948 and 1949, Professor Jean-Paul Vinay of the Université de Montréal worked on the problem with ICAO. The result was adopted on 1 November 1951 as a universal standard for spelling English letters over a telephone or radio.

It had faults. Testing showed confusion between words such as Delta, Nectar, Victor and Extra, and ICAO records that some users found the problems so severe that they went back to Able/Baker. ICAO tested again among speakers from 31 countries. Only five words were replaced, for the letters C, M, N, U and X, and the final version was implemented on 1 March 1956.

The words for the other 21 letters didn't change. The old Able/Baker list, as ICAO prints it, runs Able, Baker, Charlie, Dog, Easy, Fox, George, How, Item, Jig, King, Love, Mike, Nan, Oboe, Peter, Queen, Roger, Sugar, Tare, Uncle, Victor, William, X-ray, Yoke, Zebra.

Why Alfa and Juliett Are Spelled That Way

Two of the words aren't spelled as English speakers would write them. Reference accounts of the ICAO design say Alfa uses an F because "ph" isn't read as F in some languages, and Juliett has a double T so French speakers won't treat a single final T as silent. The words were chosen to have a similar spelling in English, French and Spanish.

One more quirk: ICAO spells the letter X as "X-ray," and the FAA's table prints "Xray." The pronunciation is the same.

Learning It

• Spell your own registration and your home airport's identifier out loud until you don't have to think.
• Practise the digit words too: tree, fife and niner.
• Listen to live ATC audio and write down the ATIS letter each time you hear one.
• Keep the aviation glossary and our guide to ATC clearances open while you practice.

Frequently Asked Questions

What's the aviation phonetic alphabet?

A set of 26 code words, Alfa through Zulu, that pilots and controllers use to spell letters over the radio. The FAA lists the words, pronunciations and Morse code in table 4-2-7 of the Aeronautical Information Manual.

Is the aviation phonetic alphabet the same as the NATO alphabet?

The letter words are the same. ICAO released the final version in 1956, and the FAA tells controllers to use the ICAO alphabet. Small spelling differences exist, such as ICAO's X-ray against the FAA table's Xray.

When did ICAO adopt the phonetic alphabet?

ICAO adopted a new alphabet on 1 November 1951, replaced five of its words after testing, and implemented the final version on 1 March 1956.

Why do pilots say niner?

ICAO's history page says nine is pronounced niner. Wikipedia says the extra syllable keeps it distinct from the German word nein.

How do pilots say a registration like N655G?

By the AIM, a pilot states the aircraft type or manufacturer, then the digits and letters, and drops the N. N655G on a Beechcraft Bonanza becomes Bonanza Six Five Five Golf.

What does Tango mean before a call sign?

The AIM says air taxi and other commercial operators without FAA-authorized call signs put the phonetic word Tango in front of their normal identification.

How do you say a radio frequency like 122.1?

The FAA says one two two point one. ICAO procedures say decimal instead of point, and the FAA honors that for aircraft required to use ICAO procedures.

Why is Juliett spelled with two Ts?

Reference accounts of the ICAO design say the double T is for French speakers, who might otherwise treat a single final T as silent.