Air Traffic Services — Page 282, Lesson 363

I want to walk you through the Flight Information Service now. This is the part of Air Traffic Services that operates outside controlled airspace, and it's a big one for your exams, so let's take it piece by piece. First, the introduction. You already know the basic unit of airspace inside a state is the Flight Information Region, the FIR. Now, here's the key theoretical point: an FIR can exist without any controlled airspace inside it. In that case, the only services provided to the traffic would be the flight information service, FIS, and the alerting service. Even where ATC is provided inside controlled airspace, FIS is still provided — it just drops to a lower priority than ATC. So FIS is always there; it's the baseline. Now, the provision of any service depends on a regular flow of information. FIS in particular leans heavily on the Aeronautical Information Service, the AIS, which each state establishes in accordance with Annex 15. I'll flag that AIS is covered in Chapter 18 of these notes, so we won't dig into it here. Next, who actually provides this service. Outside controlled airspace, and at uncontrolled aerodromes, flight information is given by Flight Information Service Officers — FISOs — operating from a Flight Information Centre, the FIC. Here's a naming convention you must remember: wherever a FIS is provided, the name of the office giving the service gets the suffix 'information'. So you'll hear callsigns like 'London Information'. FISOs are licensed to provide the FIS, but they are not permitted to offer anything that could be described as ATC. There's exactly one exception: they may provide ATC to aircraft taxiing on the ground at a controlled aerodrome, and even then it's strictly limited to movements prior to entering the runway for take-off. So once you're lining up, that's it — no more. Let me give you a concrete example. The FIS in the London FIR is provided by 'London Information', operating in three geographic sectors on dedicated VHF frequencies. Now, the operation of the service. Flight information is provided to all air traffic that is likely to be affected by the information. Specifically, that means two groups: aircraft which are provided with an ATC service, and aircraft which are otherwise known to the relevant ATS units. So it's not just the uncontrolled traffic — even aircraft under ATC get the FIS broadcast. What does the information actually include? Let me list the mandatory items. SIGMET and AIRMET — I'll define AIRMET in a moment. Volcanic eruption activity. Release of radioactive or toxic material into the atmosphere. Information concerning change of serviceability of radio navigation aids. Information concerning change of conditions concerning aerodromes. Information concerning unmanned free balloons. And other information considered pertinent to safety. On top of that, there's a second list of items that must also be provided. Weather conditions reported or forecast at departure, destination, or alternate aerodromes. Collision hazards to aircraft operating in classes C, D, E, F, and G airspace. And for flights over sea areas, when requested by pilots, details of surface vessels. Now, how is this delivered? Apart from the delivery of FIS on discrete VHF frequencies, the majority of 'routine' FIS is broadcast by the Operational Flight Information Service — that's OFIS. So think of OFIS as the routine broadcast channel, and the discrete VHF frequencies as the direct, on-request channel. Finally, the definition of AIRMET, straight from Annex 11. AIRMET is: 'Information concerning the occurrence or expected occurrence of specified en route weather phenomena which may affect the safety of low-level aircraft operations and which was not already included in the forecast issued for low-level flights in the FIR concerned or sub-area thereof.' Let me unpack that. It's about specified en route weather phenomena — so a defined set of weather events. It concerns phenomena that may affect the safety of low-level aircraft operations. And crucially, it's only issued if that information was not already included in the forecast for low-level flights in that FIR or its sub-area. So AIRMET is a supplement — it fills the gap when the routine forecast didn't already cover the hazard. There's a figure in your materials showing Volmet broadcasts, which is a related broadcast service — that's . Take a look at it on screen as we go. So to tie it together: FIS is the baseline service outside controlled airspace, provided by FISOs from a FIC, with the office name suffixed 'information'. It carries a defined list of safety-critical items, delivered either on discrete frequencies or broadcast routinely via OFIS, and AIRMET is one of those items — a specific low-level weather warning that wasn't already in the forecast.