Flight Information and Broadcast Services

Flight information and broadcast services are the ways a pilot obtains, by radio, the routine information that a flight needs but that no clearance contains: the runway in use and the weather at the destination, the altimeter setting, the state of an alternate, a NOTAM issued after departure. Some of it is given on request, by a flight information unit or, in the United States, by a flight service station. Much of it is broadcast, so that one recording serves every aircraft and the controller's frequency stays free for control.

The ICAO framework comes from Annex 11 (air traffic services) and Annex 3 (meteorological service) and is applied in Europe through EU rules such as the Standardised European Rules of the Air (SERA). The United States follows the same pattern but keeps a nationwide network of flight service stations, reached through remote radio outlets, which has no direct European equivalent. Exam questions test the definitions, the content of ATIS and VOLMET, and the way an ATIS is acknowledged.

Flight information service and aeronautical broadcasts

Flight information service (FIS) is the ICAO service that gives advice and information useful for the safe and efficient conduct of flights. It goes to aircraft known to the unit that are likely to be affected, and in Class G airspace it is available on request and is, with the alerting service, the only service provided. Units giving it use the call sign suffix INFORMATION, as in "London Information" or "Toulouse Information". An aerodrome flight information service (AFIS) does the same job at an aerodrome where no aerodrome control service is provided. Neither issues clearances: the officer passes the wind, the runway in use and known traffic, and the pilot decides (see air traffic control units).

A broadcast is, in ICAO's definition, a transmission of information relating to air navigation that is not addressed to a specific station or stations. It is one-way, from ground to air, and no reply is expected. That is its strength, since one recording serves every listener, and its limit: a broadcast is never a clearance or an instruction. It differs from a blind transmission, which is addressed to a particular station that cannot be heard to reply (see radio communication failure).

In flight a crew therefore has three main sources of routine information: the ATS unit on request, the ATIS and VOLMET. The broadcasts come first, and a controller is asked only for what they cannot supply.

ATIS

The automatic terminal information service (ATIS) is the provision of current, routine information to arriving and departing aircraft by continuous and repetitive broadcasts throughout the day or a specified part of it. Its purpose is to take the repetitive part of every first call off the approach, tower and ground frequencies. The abbreviation is spoken as a word.

The ATIS goes out on a discrete VHF frequency printed on the aerodrome charts or, to save frequencies, on the voice channel of a VOR, but never on the voice channel of an ILS. Busy aerodromes may run separate arrival and departure broadcasts: arrivals need the approach, runway and transition level, departures the runway and departure information, and splitting them keeps each message short. Where practicable, a broadcast should not last more than about 30 seconds.

A typical ICAO ATIS contains:

• the aerodrome name and the information designator, a letter of the spelling alphabet;
• the time of the observation;
• the runway in use and the type of approach to expect;
• the surface wind, in degrees magnetic, and the visibility or RVR;
• present weather and cloud, the cloud being given only when its base is below 5,000 ft or below the highest minimum sector altitude, whichever is higher, or when cumulonimbus is present;
• temperature, dew point and QNH;
• the transition level;
• warnings and other operational information, such as braking action or low visibility procedures in force.

A new broadcast, with the next letter, is recorded whenever the weather or any other item changes. On first contact the pilot quotes the letter, as in "information Romeo", so that the controller knows which edition the aircraft holds and passes only what has changed since. A pilot who quotes no letter, or an old one, has the essential aerodrome information read out. The transition level is read back even when it comes from the ATIS (see radiotelephony phraseology).

The FAA's ATIS is the same service with local detail. An arrival ATIS on a discrete frequency is normally engineered for a protected service volume of 20 to 60 NM from the site and up to 25,000 ft AGL, while a departure ATIS may not exceed 5 NM and 100 ft AGL. The broadcast is updated on receipt of every official hourly and special weather report and whenever the runway or instrument approach in use changes.

A US pilot who says "have numbers" tells the tower only that the wind, runway and altimeter setting have been received; it never stands for the ATIS. Where an airport has no ATIS, the automated weather from its ASOS or AWOS is broadcast on a separate frequency printed in the chart data block.

Digital ATIS

Digital ATIS (D-ATIS) delivers the ATIS as text by data link alongside the voice broadcast. Airline crews request it through the aircraft's ACARS data link, and it arrives on the flight deck printer or display, where it can be read at leisure and cannot be misheard (see ACARS and aircraft data link). Nothing else changes. The data link version carries the same letter, and on first contact the crew report the letter received exactly as after a voice broadcast, because the controller needs to know which edition is on board, not how it arrived.

D-ATIS should not be confused with Flight Information Service–Broadcast (FIS-B), the free US service that uplinks weather and aeronautical information to aircraft with ADS-B In on the 978 MHz UAT link (see ADS-B).

VOLMET

VOLMET, from the French vol, flight, is meteorological information for aircraft in flight: the METARs, SPECIs, TAFs and SIGMETs for a published list of aerodromes, read in sequence. Where the ATIS serves the traffic of one aerodrome, VOLMET serves every aircraft on its way to several, so that a crew can check the destination and alternates and plan a diversion without calling a controller.

• VHF VOLMET normally runs as a continuous loop, for short and medium range.
• HF VOLMET serves long-range and oceanic flights. Several stations share each frequency, and each broadcasts in its allotted time slots at fixed times past every hour; Shannon VOLMET, for example, serves the North Atlantic.

Frequencies and schedules are published in the AIP and en route supplements. The recordings are updated as new reports are issued, normally every half hour, in step with the METAR cycle. Standard meteorological terms are used and the words are spoken slowly enough to be written down. The emergency frequency 121.5 MHz is never used to ask for routine weather.

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Flight service stations

In the United States a flight service station (FSS) is an air traffic facility that gives pilot briefings, processes flight plans, provides en route flight advisories, search and rescue services and help to lost aircraft and aircraft in an emergency, relays ATC clearances, processes NOTAMs and broadcasts aviation weather and aeronautical information. In Alaska, designated stations also take weather observations and give airport advisory services. A station is called by its name followed by RADIO, as in "Seattle Radio".

In flight, Flight Service answers on the universal frequency 122.2 MHz and on the discrete frequencies of its remote outlets; on the ground pilots use 1-800-WX-BRIEF or the internet (see meteorological services and briefings). Inflight weather updates, PIREPs, opening and closing VFR flight plans and cancelling IFR at an airport without a tower all go to Flight Service. Because an FSS has direct lines to the centre's sectors, a message relayed through it reaches an air route traffic control centre faster than one relayed by company radio, and the AIM recommends that route when a centre frequency fails.

Flight Watch, the en route flight advisory service (EFAS), was a dedicated weather frequency, 122.0 MHz. It was discontinued in 2015, and its work passed to the general Flight Service frequencies. Older question banks still name it; the answer today is 122.2 MHz or an RCO frequency.

Alaskan stations also run an automatic flight information service (AFIS): a recorded broadcast like an ATIS, at airports where the FSS gives local airport advisories, updated with every official weather report. The abbreviation clashes with the ICAO aerodrome flight information service, which is a person on the radio rather than a recording.

Europe has no equivalent network. Briefings come from national aeronautical information and meteorological services and from the operator, and in flight the FIS unit answers requests.

Remote communications outlets

A remote communications outlet (RCO) is an unmanned transmitter and receiver site that extends a flight service station's radio coverage far from the station itself; the specialist works it remotely. On US sectional and en route charts an RCO appears as a box naming the site, with its frequency above and the name of the controlling FSS in a small box beneath, such as 122.15 MHz at Bellingham, worked by Seattle. A frequency printed above a VOR box means the same thing: an FSS frequency remoted to the navaid site. At most en route VORs used as ATIS voice outlets the FSS can also transmit on the VOR frequency, which interrupts the broadcast.

Air route traffic control centres apply the same idea to control. Remote Center Air/Ground (RCAG) sites, with VHF and UHF transmitters and receivers, may lie several hundred miles from the centre and are linked to it by land lines or microwave, each sector having its own discrete frequency. These centre frequencies are for IFR control; flight plan filing, weather and similar requests belong with Flight Service or company radio.

Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.