General Operating Procedures — Page 57, Lesson 45

I want to walk you through the standardised procedures for transmitting time and using standard words and phrases in radiotelephony communications. These are the building blocks of every radio call you will make as a professional pilot, so let's get them exactly right. First, time references. All time in aviation radiotelephony must be given in Coordinated Universal Time, abbreviated UTC, using the 24-hour clock. You will also hear this time zone referred to as Zulu, often written as the letter Z. Midnight is 2400, and the new day begins at 0001. So there is no 12:00 AM or PM — it is always a four-digit group from 0000 to 2359. Now, when you transmit time, you normally only need to give the minutes of the hour. For example, if the time is 0803, you would normally just say "ZERO THREE". But if there is any possibility of confusion — for instance, if the context doesn't make the hour obvious — you must include the hour as well, so you would say "ZERO EIGHT ZERO THREE". The table in front of us shows exactly how each time is transmitted and pronounced. Notice the pronunciation: "ZERO" is pronounced ZE-RO, not "oh". "THREE" is pronounced TREE, not "three". "ONE" is pronounced WUN, "FIVE" is pronounced FIFE, "SEVEN" is pronounced SEVen, and "NINE" is pronounced NIN-er. These are the standard aviation pronunciations designed to be clear over a noisy radio. So 1300 is transmitted as "ONE THREE ZERO ZERO" and pronounced "WUN TREE ZE-RO ZE-RO". 2057 can be transmitted as just "FIVE SEVEN" if the hour is obvious, pronounced "FIFE SEVen", or as "TWO ZERO FIVE SEVEN" pronounced "TOO ZE-RO FIFE SEVen". As a pilot, you may check the time with the appropriate Air Traffic Services unit, which we call the ATS unit. When they give you a time check, they shall give it to the nearest half minute. So if the actual time is 1432 and 17 seconds, the time check you receive will be 1432 and a half, or 1432 exactly if the seconds are less than 15. Now let's move to standard words and phrases. Whenever possible, you must use these standard words and phrases in radiotelephony communications. They have precise, agreed meanings, and you shall use them as appropriate. Let me go through each one. "Acknowledge" means "Let me know that you have received and understood this message." So if a controller says "Acknowledge", you need to reply to confirm you got it and understood it. "Affirm" simply means "Yes." Not "affirmative" in full — just "Affirm". "Approved" means "Permission for proposed action granted." So if you request something and the controller says "Approved", you have permission to go ahead. "Break" is used to indicate the separation between portions of a message. You use it when there is no clear distinction between the text and other portions of the message — for example, between two different pieces of information in the same transmission to the same aircraft. "Break Break" is used to indicate the separation between messages transmitted to different aircraft in a very busy environment. So if you hear "Break Break", it means the controller is switching to talk to a different aircraft. "Cancel" means "Annul the previously transmitted clearance." If a controller says "Cancel", the clearance they gave you before is now void. "Check" means "Examine a system or procedure." Importantly, no answer is normally expected. So if a controller says "Check gear down", they want you to verify it yourself, but they don't necessarily need a verbal reply. "Cleared" means "Authorized to proceed under the conditions specified." This is a key word — you are only "cleared" when you have specific permission with conditions. "Confirm" means "Have I correctly received the following ...?" or "Did you correctly receive the message?" So if a controller says "Confirm QNH 1013", they are asking you to verify that you received that value correctly. "Correct" simply means "That is correct." These are the foundational words you will use every single time you pick up the microphone. Get them right, and your communications will be precise, professional, and unambiguous.