Future Air Navigation Systems (FANS) — Page 322, Lesson 381

Right, so we’re moving into the heart of FANS now — the actual messages that fly back and forth over the data link. I want to walk you through the two big families: ATM messages, which go between the aircraft and Air Traffic Services, and AOC messages, which go between the aircraft and the airline’s operations centre. Let’s start with ATM. The book gives us three important types. First, Departure Clearance, abbreviated PDC. This is the clearance you get before you push back, sent digitally instead of by voice. Look at the example: `PDC 130044` — that’s the message type and a reference number. Then `CPA065 B742 VHHH 0100` — that’s your callsign, aircraft type, departure airport, and time. Then the meat of it: `CLEARED TO OMDB VIA 07R` — cleared to destination via runway 07R — `LAKE1A DEPARTURE V1` — that’s the SID, the standard instrument departure, and V1 is your take-off decision speed. `ROUTE: FLIGHT PLAN ROUTE` means you fly the route already filed. `MAINTAIN: 5000FT` — initial altitude to hold. `EXPECT: F330` — the altitude you can expect later, flight level 330. And `SQUAWK A5156` — the transponder code. That’s a complete departure clearance, all pre-loaded and sent by data link. Second, Oceanic Clearance. This is for the North Atlantic tracks or random routes over the ocean, where there’s no radar. Look at the example: `CLRNCE 123`, then `SAS911 CLRD TO KEWR VIA 57N010W` — cleared to New York/Newark via a waypoint at 57 North, 010 West. Then `RANDOM ROUTE` followed by a string of coordinates — `58N020W 58N030W 57N040W 55N050W OYSTR STEAM` — that’s your routing across the ocean, waypoint by waypoint. `FM 57N010W/1034` — from that first waypoint at time 1034 — `MNTN F310 M082` — maintain flight level 310, Mach 0.82. Then `ATC/ENTRY POINT CHANGE` and `ROUTE CHANGE AT 58N 20W` — these are amendments to the original clearance, telling you the entry point has changed and the route changes at that coordinate. `END OF MESSAGE` closes it out. Third, Digital ATIS. This is the Automatic Terminal Information Service, sent as text instead of a voice broadcast. Look at the example: `/HKGATYA.TI2/VHHH ARR ATIS Z 2205Z` — that’s the ATIS identifier, the airport, arrival ATIS, the letter Z, and the time. Then the content: `RWY IN USE 07R`, `EXPECT ILS DME APCH` — expect an ILS with DME approach — `WIND LIGHT AND VARIABLE`, `VIS 10 KM`, `CLOUD FEW 1600FT`, `TEMP 28 DP 22 QNH 1007` — temperature 28, dew point 22, QNH 1007. And finally `ACK Z ON FREQ 119.1 FOR ARR AND 129.9 FOR DEP` — acknowledge receipt of ATIS Z on the arrival frequency 119.1 or departure frequency 129.9. So the crew gets the full weather and runway picture without listening to a looped voice recording. Now, the second family — AOC, which stands for Aeronautical Operational Control. This is the airline side. The operator needs to know where their aircraft are at any time, to run an efficient and cost-effective operation. So a data link passes messages to and from the aircraft. The book lists four key message types, and they form a neat lifecycle of a flight. The acronym is OOOI — Out of Gate, Off Ground, On Ground, In the Gate. Let me read you the examples. Out of Gate: `OUTRP 1065/31 EGLL/KJFK .G-BOAC/OUT 0850` — that’s the report type, a reference, origin and destination, the aircraft registration, and the time it left the gate, 0850. Off Ground: `OFFRP 1247/31 EGLL/KJFK .G-BOAC/OUT 0850/OFF 0900/ETA 1525` — same structure, but now you have the off time, 0900, and the estimated time of arrival, 1525. On Ground: `ONRP 1499/31 KJFK .G-BOAC/ON 1540` — the aircraft has landed and is on the ground at 1540. In the Gate: `INRP 1803/31 KJFK .G-BOAC/ON 1540/IN 1550` — and finally, it’s at the gate at 1550. So OOOI tracks the aircraft through the whole turn: out of the gate, off the ground, back on the ground, and into the gate. Finally, the Load Sheet. This is a big one for the operator. It’s the mass and balance document, sent by data link. Let me walk you through the key fields. `LOADSHEET FINAL 9999 EDN 01` — final load sheet, edition 01. `SK9999/01 31SEP01` — flight number and date. `ARN OSL ACREG 9901S 2/4` — arrival airport, aircraft registration, and the aircraft type. Then the masses: `ZFW 49764 MAX 59874 L` — zero fuel weight, 49,764, with a maximum of 59,874, and the L indicates it’s within limits. `TOF 6100` — take-off fuel. `TOW 55864 MAX 70760` — take-off weight, 55,864, max 70,760. `TIF 2100` — trip fuel. `LAW 53764 MAX 64410` — landing weight, 53,764, max 64,410. `UNDLD 10110` — undelivered or unused fuel. Then `PAX CM 60/17 TTL 77` — passengers, 60 in one class, 17 in another, 77 total. `DOI 59` — the index for the dry operating index. `DLI 56` — the load index. `LIZFW 31` — the load index for zero fuel weight. `MAC-ZFW 7` and `MAC-TOW 10` — the mean aerodynamic chord positions for zero fuel weight and take-off weight. `TRIM BY CABIN AREA – SECTION SI` — trim instructions by cabin section. `BOARDING PAX WEIGHTS USED: -OSL ADULT 84 CHILD 35 INF 00` — the standard weights used for adults, children, and infants. `BOARDING BAG WEIGHTS USED: -OSL 13/PIECE` — baggage weight per piece. And finally the times: `TOTAL EET: 00:28` — estimated elapsed time, `AIRB TIME: 00:43` — airborne time, `ENDURANCE: 02:20` — fuel endurance, and `ALTN: ENTO` — the alternate airport. So that’s the full picture of data link messages. ATM for the air traffic side — departure clearance, oceanic clearance, digital ATIS. AOC for the airline side — the OOOI lifecycle and the load sheet. Every one of these is a structured, pre-formatted message that replaces a voice call, and that’s the whole point of FANS — moving routine communication off the radio and onto the data link.