Addendum to BAK – Paragraphs 9.85 – 9.90

Addendum to BAK – Paragraphs 9.85 – 9.90.
Please note that Trend Type Forecasts have been replaced by the TAF 3 as described in the addendum here.

Trend Type ForecastsOn 5 November 2020, the TTF services will cease and TAF 3 services will commence. The TAF 3 service will provide similar responsiveness, accuracy and operational meteorological information as the TTF.The major civilian airports affected by this change include Sydney, Melbourne, Brisbane, Perth, Adelaide, Cairns, Canberra, Darwin, Gold Coast and Hobart. At these locations, the TAF 3 service will be provided 24 hours a day, seven days a week. The TAF service provided for all other airports will remain unchanged.

Three-Hourly TAF (TAF 3)At a number of aerodromes at which a meteorological office operates, a three-hourly forecast terminal area forecast (TAF 3) is issued. The TAF 3 is defined as a responsive weather observation, incorporating the latest weather observations and future trends. This forecast is continuously monitored and amended by aviation meteorologists. This forecasts replaces the TAF, it is routinely updated every three hours and has a validity period of 18, 24 or 30 hours. The TAF 3 is to be considered more accurate than a TAF and as such the buffers (regarding validity and requirements for holding or alternate fuel) do not apply during the first three hours of TAF 3 validity only (not beyond the first three hours). The TAF3 is identical in format to the TAF and can be identified by TAF3 in the remarks (RMK) section of the TAF.


Example 1 of TAF 3TAF YMML 040430Z 0406/050027005KT CAVOKRMKT 04 05 06 08 Q 1020 1021 1022 1021TAF3 VALID TL 040900

Line 1– TAF FORECAST: Routine terminal area forecast.- YMML 040430Z: Observation for Melbourne Airport (YMML) taken at 0430 UTC on the 4th day of the month.- 0406/0500: Observation valid period is 18 hours, begins at 0600Z and ends 0000Z the following day.

Line 227005KT: The wind will be from 270° true at 5 knots.CAVOK: Visibility equal to, or greater than, 10 km. No cloud below 5,000 feet and nil significant weather.

RemarksRMKT 04 05 06 08: Temperatures at three hourly intervals. 4°C at 0600 UTC, 5°C at 0900 UTC, 6°C at 1200 UTC and 8°C at 1500 UTC.Q 1020 1021 1022 1021: QNH at three hourly intervals. 1,020 hPa at 1200 UTC, 1,021 hPa at 1500 UTC, 1,022 hPaat 1800 UTC and 1,021 hPa at 2100 UTC.TAF3: Indicated forecast is TAF3 forecast.VALID TL 040900: TAF3 valid till 0900 UTC.

Note: The BOM aims to publish 90 minutes in advance.

Note: This forecast is considered highly accurate from 0600 till 0900, during which time holding or alternate fuel buffers are not required.

REF: AIP GEN 1.1-90 para 2 of TAF 3TAF AMD YSSY 281030Z 2812/290624025G45KT 3000 +TSRA SCT013 BKN032INTER 1345/1445 VRB15G25KT 3000 -RA BKN045RMKT 26 23 22 20 Q 1002 1004 1006 1007TAF3 

Line 1TAF AMD: Amended TAF forecast.YSSY 281030Z: Forecast for Sydney Airport issued at 1030 UTC on the 28th day of the month.2812/2906: TAF validity period from 1200 UTC to 0600 UTC the following day.

Line 224025G45KT: Wind 240°T at 25 knots gusting 45 knots.3000 +TSRA: Visibility 3000 meters, heavy thunderstorms and rain.SCT013 BKN032: Cloud 3 to 4 oktas at 1,300 ft AGL, 5 to 7 oktas at 3,200 ft AGL.

Line 3INTER 1345/1445: 30 minutes holding required between 1345 and 1445 (UTC) due to weather indicated below being below the alternate minima and lasting for periods of not more than 30 minutes (Within TAF3 validity, see remarks).VRB15G25KT: The wind will be variable from 150° true at 15 knots, gusting 25 knots.3000 -RA  BKN045: 5 to 8 oktas of cloud at 4,500 ft AGL.

Remarks RMKT 26 23 22 20: Temperatures at three hourly intervals. 26°C at 1200 UTC, 23°C at 1500 UTC, 22°C at 1800 UTC and 20°C at 2100 UTC.Q 1002 1004 1006 1007: QNH at three hourly intervals. 1,002 hPa at 1200 UTC, 1,004 hPa at 1500 UTC, 1,006 hPaat 1800 UTC and 1,007 hPa at 2100 UTC.TAF3: Indicated forecast is TAF3 forecast valid till 1500 UTC.