Manual index/Reference
Glossary
Acronyms, phenomenon codes, category thresholds.
Flight categories (FAA)
- VFR
- Ceiling > 3000 ft AND visibility > 5 SM
- MVFR
- Ceiling 1000–3000 ft OR visibility 3–5 SM
- IFR
- Ceiling 500–1000 ft OR visibility 1–3 SM
- LIFR
- Ceiling < 500 ft OR visibility < 1 SM
METAR/TAF phenomenon codes
- TS
- Thunderstorm
- TSRA
- Thunderstorm with rain
- RA
- Rain
- SN
- Snow
- GR
- Large hail
- GS
- Small hail / graupel
- FG
- Fog (vis < 1 km)
- BR
- Mist (vis 1–5 km)
- HZ
- Dry haze
- FU
- Smoke
- VA
- Volcanic ash
- DS / SS
- Dust / sandstorm
- BL...
- Blowing (BLSN = blowing snow)
- CAVOK
- Ceiling and visibility OK (no clouds below 5000 ft, vis ≥ 10 km, no phenomena)
SIGMET hazard codes
- TS / TSGR / CB
- Thunderstorm (with hail or cumulonimbus)
- TURB
- Moderate or severe turbulence
- ICE / ICGIC
- Airframe icing (in clouds = ICGIC)
- MTW
- Mountain wave
- MTN OBSCN
- Mountains obscured
- VA
- Volcanic ash
- TC
- Tropical cyclone
- DS / SS
- Dust / sandstorm
- RDOACT
- Radioactive cloud
Units
- Wind
- Knots (kt)
- Visibility
- Meters (Europe) and statute miles (USA/UK)
- Ceiling and clouds
- Feet (ft) AGL
- Temperature
- Celsius (°C)
- Pressure
- Hectopascals (hPa) and inches of mercury (inHg)
- SIGMET distances
- Nautical miles (NM)