For example, you might see KLM511, NGA213, or JTR25 — Page 233, Lesson 233

I want to walk you through the ATC Flight Plan items that define who is flying, what rules they're following, what aircraft they're in, and what equipment they have on board. Let's start with the flight identification. Item 7 of the flight plan is where you put the aircraft operating agency followed by the flight identification. For example, you might see KLM511, NGA213, or JTR25. Now, when you're actually talking on the radio, the call sign the aircraft uses will consist of the ICAO telephony designator for the operating agency, followed by the flight identification. So KLM511 becomes just "KLM511" on the radio, NGA213 becomes "NIGERIA 213", and JTR25 becomes "HERBIE 25". The ICAO telephony designator is the spoken name for the airline or operator — KLM is "KLM", NGA is "NIGERIA", JTR is "HERBIE". The rules for radio-telephony call signs come from ICAO Annex 10, Volume II, Chapter 5, and the official designators for operating agencies are listed in ICAO Document 8585. Now let's move to Item 8: Flight Rules and Type of Flight. This item has two parts, and you fill it with one or two characters. First, the flight rules. You insert one letter to say what category of flight rules the pilot intends to comply with. If it's IFR, you put I. If it's VFR, you put V. If you're starting IFR but plan to change to VFR at some point, you put Y, and then in Item 15 you must specify the point or points where that change happens. If you're starting VFR and plan to change to IFR, you put Z, and again specify the change point in Item 15. Second, the type of flight. You insert one letter when the appropriate ATS authority requires it. S means scheduled air service. N means non-scheduled air transport operation. G means general aviation. M means military. X means anything that doesn't fit the other categories. Next, Item 9: Number and Type of Aircraft and Wake Turbulence Category. This item has three parts. First, the number of aircraft. If you're flying a single aircraft, you leave this blank or put 1. If you're in a formation of more than one aircraft, you insert the number — one or two characters. Second, the type of aircraft. You insert the appropriate designator from ICAO Document 8643, which is the Aircraft Type Designators document. For example, a Boeing 737 might be B737, an Airbus A320 is A320. If no designator has been assigned, or if you're in a formation flight with more than one type, you insert ZZZZ, and then in Item 18 you must specify the numbers and types of aircraft preceded by TYP/. Third, the wake turbulence category. You insert an oblique stroke — that's a forward slash — followed by one letter. H means HEAVY, for aircraft with a maximum certificated take-off mass of 136,000 kg or more. M means MEDIUM, for aircraft with a maximum certificated take-off mass of less than 136,000 kg but more than 7,000 kg. L means LIGHT, for aircraft with a maximum certificated take-off mass of 7,000 kg or less. So a Boeing 747 would be /H, an A320 would be /M, and a Cessna 172 would be /L. Now Item 10: Equipment. This covers radio communication, navigation, and approach aid equipment. You have two ways to fill this. First, you can insert a single letter: N if no COM/NAV/approach aid equipment for the route is carried, or if the equipment is unserviceable. S if standard COM/NAV/approach aid equipment for the route is carried and serviceable. Second, you can insert one or more letters to indicate specific equipment that is available and serviceable. Let me run through them. A and B are not allocated. C is LORAN C. D is DME — Distance Measuring Equipment. E is not allocated. F is ADF — Automatic Direction Finder. G is GNSS — Global Navigation Satellite System. H is HF RTF — High Frequency Radio Telephony. I is Inertial Navigation. J is Data Link. K is MLS — Microwave Landing System. L is ILS — Instrument Landing System. M is Omega. O is VOR — VHF Omnidirectional Range. P and Q are not allocated. R is RNP type certification — Required Navigation Performance. T is TACAN. U is UHF RTF — Ultra High Frequency Radio Telephony. V is VHF RTF — Very High Frequency Radio Telephony. W, X, and Y are used when prescribed by ATS — Air Traffic Services. So for a typical airliner with VHF radio, VOR, DME, ILS, and GNSS, you might see S or you might list V, O, D, L, G individually. The key is that you only list what's actually available and serviceable for the route.