London Airways this is GABCD, Pole Hill at 35, FL170, Dean Cross at 46… — Page 115, Lesson 184

Right, let's pick this up with the end of a routine position report. You just heard that call — "London Airways this is GABCD, Pole Hill at 35, FL170, Dean Cross at 46, Glasgow next." That's the standard way a pilot hands over their position to air traffic control, and it leads us straight into three important rules about how a controlled flight behaves. First, termination of control. The rule is simple: a controlled flight must advise the appropriate ATCU — that's the Air Traffic Control Unit — as soon as it ceases to be subject to air traffic control services. In plain terms, the moment you're no longer being looked after by ATC, you tell them. Now, there's an automatic case here. If you land at a controlled aerodrome — and that's defined for us as one with a control tower — then the termination happens automatically. You don't need to make a special call; landing at that tower-controlled field does the job for you. But there's also a manual case. A pilot may be requested to advise ATC when the aircraft leaves controlled airspace. So if you're exiting controlled airspace, ATC can ask you to call them and confirm that you're leaving their service. Next, communications failure. This is a big one. Aircraft operating in accordance with an ATC clearance, where two-way radio communications are required, must comply with the requirements of ICAO Annex 10, which is the Telecommunications annex, Volume 2. That annex specifies the requirement for air-to-ground communications equipment and the radio frequencies allocated to the aeronautical mobile telecommunications network. Let me unpack that. The aeronautical mobile telecommunications network is the radio system that lets aircraft talk to ground stations. And there's a neat point here — SELCAL satisfies the requirement to maintain air-ground voice communications. SELCAL is selective calling; it's a system that alerts the crew when the ground wants to talk to them, so they don't have to sit listening to a quiet frequency the whole time. That counts as maintaining the voice link. And then there's a modern twist: where Controller-Pilot Data Link Communications — CPDLC — exists, the requirement for voice communications is required to be maintained. So even if you're using datalink, you still have to keep the voice channel alive. The datalink doesn't replace the voice requirement. Finally, confirmation of communication failure. How does ATC know you've actually lost comms? They confirm it by requesting you to execute a specific manoeuvre which can be observed by radar, or transmit a signal to indicate acknowledgement. So either you do something visible on the radar screen, or you send a signal that shows you've received them. And regardless of that, in any case, ATC will transmit blind instructions to the aircraft on frequencies on which the aircraft is believed to be listening. Blind transmission means they broadcast the instructions without expecting a reply — they just put it out on the frequencies they think you're monitoring, hoping you'll pick it up. So the thread through all three is this: know when your control service ends and say so, keep your communications equipment and voice link up to the standard the annex demands, and understand how ATC will try to reach you if they think you've gone silent. That's the discipline of operating as a controlled flight.