AMC1 ATS.TR.305 Scope of flight information service

TRANSMISSION OF INFORMATION

(a)     Means of transmission

(1)     Information should be disseminated to aircraft by one or more of the following means:

(i)      the preferred method of directed transmission on the initiative of the appropriate air traffic services unit to an aircraft, ensuring that receipt is acknowledged; or

(ii)     general call, unacknowledged transmission to all aircraft concerned; or

(iii)     broadcast; or

(iv)     data link.

(2)     The use of general calls should be limited to cases where it is necessary to disseminate essential information to several aircraft without delay, e.g. the sudden occurrence of hazards, a change of the runway-in-use, or the failure of a key approach and landing aid.

(b)     Transmission of special air-reports, SIGMET and AIRMET information

(1)     Appropriate SIGMET and AIRMET information, as well as special air-reports which have not been used for the preparation of a SIGMET, should be disseminated to aircraft by one or more of the means specified in point (a) as established by the competent authority. Special air-reports should be transmitted with the least possible delay and disseminated to aircraft for a period of 60 minutes after their issuance.

(2)     The special air-report, SIGMET and AIRMET information to be passed on to aircraft on ground initiative should cover a portion of the route up to 1 hour’s flying time ahead of the aircraft.

(c)      Transmission of information concerning volcanic activity

         Information concerning pre-eruption volcanic activity, volcanic eruptions and volcanic ash clouds (position of clouds and flight levels affected) should be disseminated to aircraft by one or more of the means specified in point (a) as established by the competent authority.

(d)     Transmission of information concerning radioactive materials and toxic chemical clouds

         Information on the release into the atmosphere of radioactive materials or toxic chemicals which could affect airspace within the area of responsibility of the air traffic services unit should be transmitted to aircraft by one or more of the means specified in point (a).

(e)     Transmission of local special reports, SPECI and amended TAF

(1)     Special reports and amended TAF should be transmitted on request and supplemented by:

(i)      directed transmission from the appropriate air traffic services unit of selected special reports and amended TAF for the departure, destination and its alternate aerodromes, as listed in the flight plan; or

(ii)     a general call on appropriate frequencies for the unacknowledged transmission to affected aircraft of selected special reports and amended TAF; or

(iii)     continuous or frequent broadcast or the use of data link to make available current METAR and TAF in areas determined on the basis of regional air navigation agreements where traffic congestion dictates. VOLMET broadcasts and/or D-VOLMET should be used to serve this purpose.

(2)     The passing of amended aerodrome forecasts to aircraft on the initiative of the appropriate air traffic services unit should be limited to that portion of the flight where the aircraft is within a specified time from the aerodrome of destination, such time being established on the basis of regional air navigation agreements.

(3)     SPECI should, when issued for aerodromes not serving scheduled commercial air transport, be transmitted on request.

(f)      Transmission of information on heavy or medium unmanned free balloons

Appropriate information on heavy or medium unmanned free balloons should be disseminated to aircraft by one or more of the means specified in point (a).

(g)     Transmission of information to supersonic aircraft

The following information should be available at appropriate ACCs or flight information centres for aerodromes determined by the competent authority and should be transmitted on request to supersonic aircraft prior to commencement of deceleration/descent from supersonic cruise:

(1)     current meteorological reports and forecasts, except that where communications difficulties are encountered under conditions of poor propagation, the elements transmitted may be limited to:

(i)      mean surface wind, direction and speed (including gusts);

(ii)     visibility or RVR;

(iii)     amount and height of base of low clouds;

(iv)     other significant information; and

(v)      if appropriate, information regarding expected changes;

(2)     operationally significant information on the status of facilities relating to the runway-in-use, including the precision approach category in the event that the lowest approach category promulgated for the runway is not available; and

(3)     sufficient information on the runway surface conditions to permit assessment of the runway braking action.