To kick things off, today’s post launches a new series called: “Ask Oscar, The Pilot,” where I aim to answer popular questions commonly asked of pilots, starting with: Why Do Pilots Say Niner?
NB: You can submit your question by dropping me an email: ([email protected]) or through the Contact page.
Question: Why do pilots say Niner instead of just saying nine?
To begin with, before diving into the answer, we need to introduce a few concepts first.
1. Aviation English (AKA. Pilot English):
English is widely used in aviation. In fact, ICAO states the following:
5.2.1.2.1Â The air-ground radiotelephony communications shall be conducted in the language normally used by the station on the ground or in the English language. [1]
5.2.1.2.2Â The English language shall be available, on request from any aircraft station, at all stations on the ground serving designated airports and routes used by international air services. [2]
2.31.2Â Except when communications between air traffic control units are conducted in a mutually agreed language, the English language shall be used for such communications. [3]
Furthermore, pilots need to hold a sufficient level of proficiency in English. Aviation has a ‘special’ language, a secret* one that I will unveil to the world now:
*A bit of exaggeration for dramatic purposes.
“Standard Phraseology” is a concept in radio communications. Essentially, it enables pilots to communicate using what we’ll call for the sake of this article: “Standard Aviation Language.”
Now: What is this “Standard Aviation Language”?
It’s a tweaked version of English or, more precisely: “A particular way to pronounce English”.
1.2 How do pilots pronounce the alphabet? ICAO Phonetic Alphabet:
The standard alphabet has a phonetic pronunciation for each letter. The sound should be the same, regardless of the speaker’s native language! [4] Find the ICAO Phonetic Alphabet in the picture below:
1.3 How do pilots pronounce numbers? ICAO Phonetic Numbers:
Similarly, like the alphabet, numbers have a unique pronunciation in aviation. Find the ICAO Phonetic Numbers in the picture below:
2.0 What’s the point of pilots doing all of that?
Enough of the introductory concepts. The question remains:
Why do pilots say NINER instead of Nine?
Why do pilots say TREE instead of THREE?
The answer to all of this is to avoid confusion for the following reasons:
- The cockpit is a noisy environment, and you need to speak loudly so the other pilot can hear and understand you, let alone speaking over the radio with the controller.
- The radio reception can sometimes be poor, making it difficult for the tower and pilots to understand each other.
- Pilots tend to speak faster in busy airspaces so they don’t block the frequency, which may lead to skipping letters and numbers.
- There may be words that sound similar and could be confused. For example, the letter ‘A’ could be confused with the number ‘8’, or the letter ‘C’ (see), which sounds like ‘D’ (dee) or ‘V’ (vee). [5]
- Pilots and controllers come from various backgrounds and nations, each with different accents, some of which can be hard to comprehend.
- Callsign confusion can occur. Callsigns with similar sounds on the same radio frequency can lead to a crew mistakenly thinking a specific clearance is directed at them when it’s intended for another aircraft.
As a result, to avoid confusion due to the reasons mentioned, pilots may be asked to repeat a clearance or read back a frequency using individual letters or numbers. This is where the ‘special’ alphabet and number pronunciations come into play.
Example:
*Made-up example – not an actual frequency, radar name, or aircraft callsign*
“Oscar 520, contact AvPosts radar 123.495”
- Suppose you mishear the controller and read back the frequency incorrectly.
- In response, the controller will notice the mistake, repeat the frequency, and ask you for a readback.
This time, you read back using ICAO Phonetic Numbers to avoid any further confusion. In other words, your transmission will sound like this:
“Contact AvPosts radar WUN TOO TREE DAYSEEMAL FOWER NINER FIFE, OSCAR FIFE TOO ZERO”
I hope this answers your question! If you have further questions, please send them my way. I’ll be happy to answer.
References:
[1] [2] [3] ICAO (2016). Language to be used. In Aeronautical Telecommunications. Annex 10 to the Convention on International Civil Aviation (7th ed, vol. 2, pp. 80). https://store.icao.int/en/annex-10-aeronautical-telecommunications-volume-ii-communication-procedures-including-those-with-pans-status
[4] [5] CAE Oxford Aviation Academy. (2015). Transmission of Letters and Numbers. In Communications (EASA FIRST EDITION REVISED FOR NPA 29, Vol. 14, Ser. ATPL GROUND TRAINING, pp. 3–3). https://www.caeoxfordinteractive.com/index.php?route=product/product&path=82&product_id=194
ICAO (2007). GENERAL OPERATING PROCEDURES. In Manual of radiotelephony. Doc 9432-AN/925 (4th ed., pp. 19–20). https://store.icao.int/en/manual-of-radiotelephony-doc-9432
