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Flight/weather rules
Each station is categorized into one flight or weather rule based on the latest METAR observations. Some rule systems are
defined and can be used in the app.
The following rule systems are defined:
GAFOR (Germany)
The German GAFOR system uses color / letter codes. Some of these codes will further divided using a number. The following codes
are defined:
| GAFOR code |
Color |
Visibility |
Ceiling |
| X - Closed |
Red |
< 1,5 km |
< 500 ft |
| M2 - Marginal 2 |
Orange |
> 8 km |
< 1000 ft |
| M5 - Marginal 5 |
Orange |
5 - 8 km |
< 1000 ft |
| M6 - Marginal 6 |
Orange |
1,5 - 5 km |
> 2000 ft |
| M7 - Marginal 7 |
Orange |
1,5 - 5 km |
1000 - 2000 ft |
| M8 - Marginal 8 |
Orange |
1,5 - 5 km |
< 1000 ft |
| D1 - Difficult 1 |
Yellow |
> 8 km |
1000 - 2000 ft |
| D3 - Difficult 3 |
Yellow |
5 - 8 km |
> 2000 ft |
| D4 - Difficult 4 |
Yellow |
5 - 8 km |
1000 - 2000 ft |
| O - Open |
Green |
> 8 km |
> 2000 ft |
| C - CAVOK |
Blue |
> 10 km |
> 5000 ft |
American
The U.S. system from NOAA defines 4 different rules:
| Rule |
Visibility |
Ceiling |
| LIFR (Low IFR) |
< 1 sm |
< 500 ft |
| IFR |
1 - 3 sm |
500 - 1000 ft |
| MVFR (Marginal VFR) |
3 - 5 sm |
100 - 3000 ft |
| VFR |
> 3 sm |
> 3000 ft |
Military
The military system defines various color codes:
| Color code |
Visibility |
Ceiling |
| RED (red) |
< 800 m |
< 200 ft |
| AMB (amber) |
800 - 1600 m |
200 - 300 ft |
| YLO (yellow) |
1600 - 3700 m |
300 - 700 ft |
| GRN (green) |
3700 - 5000 m |
700 - 1500 ft |
| WHT (white) |
5000 - 8000 m |
1500 - 2500 ft |
| BLU (blue) |
> 8000 m |
> 2500 ft |
ICAO
ICAO rules only define IMC and VMC. IMC is defined as a visibility of less than 5000 m and / or a ceiling of less than 1500
ft; otherwise the current rule is VMC.