Terminal Aerodrome Forecast

The Terminal Aerodrome Forecast (TAF ) is an aviation weather forecast for major airfields. Form, content and meaning of the TAF are standardized internationally through ICAO guidelines.

A TAF consists of a header, information about wind and wind speed, visibility, current weather phenomena, cloud height and coverage for a maximum of 3 clouds Stock works, and projected changes in these ratios within the validity period. The counterpart to the METAR TAF forms which reflects the actual observed weather conditions for each date.

In Germany TAFs are issued by the German Weather Service ( DWD).

  • 2.1 interpretation
  • 4.1 Examples

General syntax

TAF units

In Germany, the following units are used:

  • Horizontal Distances: m. Example: ground visibility.
  • Vertical distances: ft. Example: main cloud base, reported in 100ft increments.
  • Speeds: kts. Example: wind speed.
  • Direction: degrees related to the geographic North Pole. Example: wind direction.
  • Time: All times are given absolutely by means of two defined points in time. Reference system is always UTC.

International Standard

ICAO Member States may generally deviate from the prescribed standards, but this normally only in details. In the U.S., for example, is " unlimited " Visibility is not specified with the group " 9999" ( 10,000 or more), but with " P6SM " ( "plus 6 statute miles" - more than 6 statute miles ).

In this article, the German standard is described. Germany follows the ICAO standards.

Example

A slightly longer TAF from September 4, 2011 from Frankfurt ( EDDF )

TAF EDDF 041100Z 0412 / 0518     22008KT 9999 SCT035     TEMPO 0414/0420 SHRA BKN030CB     PROB30 TEMPO 0414 / 0420 25015G25KT 2000 TSRA BKN014     TEMPO 0420/0502 4000 RA BKN014     PROB30 TEMPO 0502 / 0508 4000 SHRA BR BKN012CB     PROB30 TEMPO 0505 / 0515 26015G25KT interpretation

The key to the interpretation of the weather phenomena is the same as for METARs and will not be explained again here.

Change groups

In contrast to the METAR, which expresses only the observed time of creation weather that TAF can play as a forecast over a longer period different weather conditions. The DWD explains:

"With the expected significant change ( reaching, exceeding or falling below a defined threshold, the beginning and end of significant weather phenomena ) of the forecast period is divided. This is done with the aid of modification groups. All change groups are connected to a time group. "

Change groups are TAF - specific and are initiated using the TEMPO key guards, BECMG and FM. If the occurrence of a state described by TEMPO unsure this can be assigned using the PROB - keyword a percentage chance. This is generally either 30 or 40%.

TAF corrections or Amendierungen

Issued TAFs can be corrected or rectified in retrospect, was to prove the necessity. The DWD explains:

" Issued TAFs be corrected when serious deviations from the original forecasts have occurred or are expected. A corrected TAF AMD ( amendment to: correct ) in ".

Examples

Here are some real examples amendierter / corrected TAFs of 4 September 2011:

  • ' TAF AMD EDJA 041530Z 0416 / 0420 30010KT 4000 TSRA SCT012 BKN035CB BECMG 0416 / 0418 NSW SCT015 BKN040 TEMPO 0418 / 0420 RA =
  • ' TAF AMD EDTL 041655Z 0417 / 0424 CNL =
  • ' TAF AMD ETAD 0412/0511 19015KT 9999 SCT025 BKN030 QNH2983INS BECMG 0413 / 0414 8000 SHRA SCT025 BKN060 21015G20KT QNH2984INS BECMG 0418 / 0419 23007KT 9999 NSW SCT025 BKN100 QNH2983INS BECMG 0423 / 0424 20007KT 9999 BKN015 OVC040 QNH2983INS T23/0412Z T11/0503Z AMD 041 225 LIMITED METWATCH 0412 TIL 0604 =
  • ' TAF COR EDGS 041700Z 0418 / 0421 27006KT 9999 SCT015 TEMPO 0418 / 0421 20006KT 2500 RA BKN006 =

Recent legal changes

( 24 h) and long -TAF canceled - With effect from 5 November 2008, the distinction was in Germany in short (9 h). The German Weather Service ( DWD), thereby implementing the provisions of ICAO Annex 3, Amendment 74.

The validity period of a TAF is now extended to a maximum of 30 hours. In Germany, 30 hour forecasts only for the airports in Munich, Frankfurt, Cologne and Hamburg ( ICAO designator: EDDM, EDDF, EDDK and EDDH be issued). The remaining airports / courts get 24 - or 9 -hour forecasts.

The timeliness compared to the previous short -TAF is through supplements - characterized by AMD - guaranteed to the first edition. Example: TAF AMD EDDM 061100Z ...

Corrections are indicated by COR.

To produce uniqueness, the groups time now additionally contain the validity.

Example: TAF EDDM 061100Z 0612 / 0718 - The forecast period is from 6th of the month, 12:00 UTC clock to the 7th, 18:00 UTC clock.

In a cloudless sky NSC ("no significant clouds" ) is given in the future, if the conditions for " CAVOK " are not sufficient.

International Civil Aviation Organization Deutscher Wetterdienst Knot (unit)
339098
de