The frequency being used — Page 66, Lesson 51

I want to walk you through the procedures surrounding the frequency being used and the transfer of communications. Let's start with how frequency changes are normally handled. An aircraft will normally be advised by the appropriate aeronautical station to change from one frequency to another. So the ground controller tells you to switch. For example, they might say: "Fastair 345 contact Wrayton control 129.1." That's the controller telling you to call Wrayton Control on 129.1 megahertz. Your correct response as a pilot is to read back the frequency and your call sign: "Wrayton control 129.1 Fastair 345." Notice you repeat the frequency and the station you're contacting, then your own call sign. Now, what if you as the pilot want to change frequency? That's called "Pilot's Choice." If you wish to change frequency, you should notify the change as appropriate. For example: "Oxford Approach, G-BODA changing to Brize Radar 134.3." You tell the current controller which frequency you're moving to. ICAO Annex 10 also gives this advice: "When establishing initial contact, or when leaving a VHF frequency, an aircraft station shall transmit such information as may be prescribed by the appropriate authority." So when you first call a new station or when you leave a frequency, you must transmit whatever information the local authority requires — typically your call sign and the frequency you're leaving or joining. There's also a timing rule. After a call has been made to an aeronautical station, a period of at least 10 seconds should elapse before a second call is made. So if you call and get no reply, wait at least ten seconds before trying again. Don't keep calling immediately. What about broadcasting to everyone? Stations having a requirement to transmit information to all stations likely to intercept the call should preface the transmission with the general call "ALL STATIONS," followed by the identification of the calling station. So you'd say something like "ALL STATIONS, this is Fastair 345." No reply is expected unless individual stations are subsequently called to acknowledge receipt. So it's a broadcast, not a conversation. Now let's move to readback of clearances. A clearance can vary — from a detailed description of a route and levels to be flown, to the name of a standard route such as a Standard Instrument Departure, known as a "SID." Clearances should be passed slowly to enable pilots to write down the information. If possible, a clearance is passed before start up and certainly not when a pilot is engaged in manoeuvring his aircraft. Of course, multi-crew aircraft don't have a problem here because one pilot can handle the radios while the other flies. There is a specific list of ATC messages that must be read back in full by the pilot. These are: - Level instructions - Heading instructions - Speed instructions - ATC route clearances - Runway in use - Clearance to: enter, land on, take off, back-track, cross, hold short of active runway - SSR operating instructions — that's Secondary Surveillance Radar, your transponder codes - VDF information — VHF Direction Finding information - Frequency changes - Type of radar service - Altimeter settings If the controller does not receive a readback, he will instruct the pilot to do so. If the pilot does not understand the message, he is expected to request that messages are repeated or clarified. So if you're unsure, ask for a repeat. Here's a critical point: a route clearance is not a clearance to enter an active runway or to take off. They are separate things. The words "TAKE OFF" are only used when an aircraft is cleared to take off or when cancelling a take-off clearance. At all other times, the words "DEPARTURE" and "AIRBORNE" are used. So you never say "take off" casually — you say "departure" or "airborne" when discussing leaving the ground in a non-clearance context. ATC route clearances shall always be read back, unless otherwise authorized by the appropriate ATS authority. And clearances and readbacks always include the aircraft call sign. In a readback, the last thing you say is your call sign. So you read back the clearance, then your call sign at the end. Finally, JAR-FCL — the Joint Aviation Requirements for Flight Crew Licensing — makes particular mention of the need to read back the following clearances: - ATC route clearances - Clearances related to runway in use - Other clearances such as conditional clearances - Data such as runway, altimeter settings, SSR codes, etc. So those items are specifically highlighted as requiring readback under the licensing standards.