Terminal Aerodrome Forecast (TAF)
Definition
A TAF (Terminal Aerodrome Forecast) is an official, aviation-specific weather forecast issued for airports. It provides a concise summary of expected meteorological conditions in the vicinity of an aerodrome, typically within a 5 NM radius, over a 30-hour or 24-hour period (occasionally 9 or 12 hours for smaller airports).
TAFs are issued by meteorological authorities and are formatted according to ICAO standards for international use.
Purpose
- Help pilots plan departure and arrival operations
- Assist in alternate airport selection
- Provide essential input for IFR fuel planning, approach minima, and contingency strategies
Format Overview
A typical TAF includes:
- Airport ICAO code
- Date/time of issuance
- Forecast validity period
- Forecasted wind, visibility, weather phenomena, cloud layers
- Probability and timing of changes (e.g., TEMPO, BECMG, PROB)
Example TAF
LOWW 081100Z 0812/0918 27008KT 9999 SCT030
BECMG 0814/0816 32012KT
TEMPO 0816/0820 4000 -RA BKN020
PROB30 TEMPO 0900/0904 2000 TSRA
Decoded:
- LOWW: Vienna International Airport
- 081100Z: Issued on the 8th day at 1100 UTC
- 0812/0918: Valid from the 8th at 12:00 UTC until the 9th at 18:00 UTC
- 27008KT: Wind from 270° at 8 knots
- 9999: Visibility 10 km or more
- SCT030: Scattered clouds at 3000 ft
- BECMG 0814/0816: Becoming between 14:00–16:00 UTC
- 32012KT: New wind from 320° at 12 knots
- TEMPO 0816/0820: Temporary condition between 16:00–20:00 UTC
- 4000 -RA BKN020: Visibility 4 km, light rain, broken clouds at 2000 ft
- PROB30 TEMPO 0900/0904 2000 TSRA: 30% chance of thunderstorms with rain, 2 km visibility from 00:00–04:00 on the 9th
Key TAF Elements
| Code | Meaning |
|---|---|
| KT | Wind in knots |
| 9999 | Visibility 10 km or more |
| SCT/BKN/OVC | Cloud coverage: Scattered, Broken, Overcast |
| BECMG | Gradual change in weather |
| TEMPO | Temporary weather conditions |
| PROB | Probability of certain weather (e.g., PROB30 = 30%) |
| CB | Cumulonimbus clouds (severe weather risk) |
TAF vs. METAR
| Feature | TAF | METAR |
|---|---|---|
| Type | Forecast | Actual observation |
| Duration | 9–30 hours | Updated every hour |
| Use | Planning | Real-time conditions |
| Format | Predictive | Snapshot |
Why TAFs Matter
- ✅ Critical for fuel planning and alternates
- ✅ Used to determine landing and takeoff minima
- ✅ Aid in assessing weather-related delays or rerouting
- ✅ Required for IFR pre-flight planning
Tips for Pilots
- Always compare TAF with METAR to assess trends
- Monitor BECMG/TEMPO to anticipate weather windows
- Use LearnATC to practice interpreting and applying TAFs to real scenarios
- Check for TAF amendments (TAF AMD) that override previous forecasts