Future Air Navigation Systems (FANS) — Page 322, Lesson 383

Let’s start with the big picture. We’re looking at Future Air Navigation Systems, or FANS — that’s the umbrella concept for moving aviation communication away from voice-only radio and toward data link, where messages are sent as text and data rather than spoken words. The whole point is to reduce congestion on voice channels, cut down on misunderstandings, and let the aircraft and the ground system exchange information automatically and precisely. I want to walk you through two very practical examples of data link in action, straight from the cockpit and cabin environment. The first is Passenger Information, and the second is Weather Reports. These are real messages that get transmitted over the data link, and you need to be able to read them like a professional. --- Passenger Information This message is used by the cabin crew to help transferring passengers — that is, passengers who are connecting from one flight to another. The data link sends the cabin crew a clear, structured summary of each connecting passenger’s situation. Let me decode the header. The message type is PASSENGERINFO, and it’s marked NEW — meaning this is a new message, not an update. Then we have the aircraft identifier, ATT SK0864. That’s the aircraft tail or flight identifier, and SK0864 is the flight number. Then we get the ETA, the estimated time of arrival — here it’s 1235, so 12:35. The GATE is 03A, the TERM is T5 — that’s terminal 5 — and BC is the boarding class or boarding category. Then we see REBOOKED, which tells the crew that this passenger has been rebooked onto a different flight. Now the body of the message is split into two sections. The first is REBOOKED — the passenger’s original destination and flight, and the new one. Look at the line: DEST FLT ETD N-ETD N-FLT GATE TM CITY. That’s destination, flight number, ETD — estimated time of departure — then N-ETD, the new estimated time of departure, N-FLT, the new flight number, the gate, the terminal, and the city. So for example, -OER SK2092 1215 1440 SK0094 T4 OERNSKOELDSVIK — the original flight SK2092 to Oernskoeldsvik, departing 12:15, has been rebooked to flight SK0094, new departure 14:40, gate T4. Same for -VXO SK1151 1240 1520 SK1157 T4 VAEXJOE — original flight SK1151 to Vaexjoe, rebooked to SK1157, new departure 15:20. The second section is CONNECTIONS — these are the passenger’s onward connecting flights. Each line gives DEST (destination), FLT (flight number), ETD (estimated time of departure), GATE, TM (terminal), and CITY. For example, -HEL KF440 1300 04A T5 HELSINKI — flight KF440 to Helsinki, departing 13:00, gate 04A, terminal 5. And so on down the list: Frankfurt, Riga, Koebenhavn, Moscow-Sheremetyevo, Joenkoeping, Tallinn. Each one is a separate connection the crew needs to manage. At the bottom we have SIGNED: PSJ — that’s the signature or identifier of the person or system that sent the message. Then LN-BRQ is the aircraft registration, and NEXT FLIGHT SK0861 ARN OSL STD 09:55 — the next flight is SK0861 from ARN (Stockholm Arlanda) to OSL (Oslo), with a STD, a scheduled time of departure, of 09:55. And PLANNED ?T/A 00:30 — that’s the planned turnaround time, 30 minutes. Finally, END marks the end of the message. So the cabin crew gets all of this in one text block — no voice call, no ambiguity. That’s the power of data link for passenger handling. --- Weather Reports Now the second example — weather. This is a data link message that bundles several standard aviation weather products together. Let me walk you through each one, because you’ll see these formats throughout your career. The header is /HKGVOYA.TI2/VHHH ENR ATIS. That’s the address — the message is going to VHHH, which is Hong Kong International Airport. ENR means en-route, and ATIS is the Automatic Terminal Information Service — the continuous broadcast of current airport weather and runway information. Then we have VHHK SIGMET A2 VALID 090530/090930. A SIGMET is a significant meteorological information message — it warns of weather that could affect aircraft safety, like thunderstorms, turbulence, icing, or volcanic ash. A2 is the message identifier. VALID 090530/090930 gives the validity period — from the 09th day at 05:30 UTC to the 09th day at 09:30 UTC. Then the body: VHHHHONG KONG CTA EMBD TS FCST S OF N19 E OF E114 TOP FL 350 STNR NC. Let me decode that. CTA is control area. EMBD TS is embedded thunderstorms — thunderstorms that are hidden inside cloud layers. FCST means forecast. S OF N19 E OF E114 — south of latitude 19 North, east of longitude 114 East. TOP FL 350 — the cloud tops are at flight level 350, which is 35,000 feet. STNR means stationary — the system is not moving. NC means no change — the situation is expected to remain as forecast. Then we get a series of METARs. A METAR is a routine aviation weather report — the actual observed weather at an airport, not a forecast. Let me read one carefully, because this is a skill you must master. METAR VHHH 090730Z 16011KT 130V190 9999 SCT028 BKN300 33/23 Q1007 NOSIG= - VHHH — the station, Hong Kong. - 090730Z — the date and time: the 09th day at 07:30 Z, which is Zulu time, i.e., UTC. - 16011KT — wind from 160 degrees at 11 knots. - 130V190 — the wind direction is varying between 130 and 190 degrees. - 9999 — visibility is 10 kilometres or more, the maximum reported. - SCT028 — scattered cloud at 2,800 feet. - BKN300 — broken cloud at 30,000 feet. - 33/23 — temperature 33°C, dew point 23°C. - Q1007 — QNH, the altimeter setting, is 1007 hectopascals. - NOSIG — no significant change expected. - The = sign marks the end of that METAR. Then we have more METARs from other stations. METAR ZGGG is Guangzhou — note the wind is given in MPS, metres per second, not knots: 13004MPS. That’s a regional difference you’ll see in some parts of the world. It also has FEW040TCU — few clouds at 4,000 feet, and TCU means towering cumulus. Then METAR ROAH is Okinawa, METAR RCTP is Taipei — and look at that one: TEMPO 3000 -SHRA. TEMPO means temporarily, and 3000 is visibility of 3,000 metres, with -SHRA meaning light rain showers. So the weather at Taipei is expected to temporarily drop to 3,000 metres visibility with light rain showers. Then METAR RCKH is Kaohsiung, and METAR RPLL is Manila — note TCU W at the end, meaning towering cumulus to the west. And METAR RPVM is Cebu — and here the pressure is given as A2976, which is in inches of mercury rather than hectopascals. So you see, the same METAR format, but units can vary by region. Finally, we have a TAF — a Terminal Aerodrome Forecast. This is the forecast for an airport, as opposed to the observed METAR. The excerpt shows TAF VHHH 090530Z 090615 18010KT 9999 — that’s the forecast for Hong Kong, issued on the 09th at 05:30 Z, valid from 06:15, wind from 180 degrees at 10 knots, visibility 10 kilometres or more. The message is cut off there, but you get the structure. --- So here’s the takeaway. Under FANS, the aircraft and the ground exchange these structured text messages over data link. The cabin crew gets passenger connection details in a clean, readable format. The flight crew gets SIGMETs, METARs, and TAFs delivered directly, without having to copy a long voice broadcast and risk transcription errors. Every element — the ETA, the gate, the flight level, the QNH, the validity period — is precise, and precision is what keeps operations safe and efficient. That’s the core of what I want you to take from this: data link turns communication into structured, unambiguous data, and you need to be fluent in reading it.