Key notes
ISA & altimetry
Section titled “ISA & altimetry”| Item | Value |
|---|---|
| MSL temp | +15°C |
| MSL pressure | 1013.25 hPa |
| MSL density | 1.225 kg/m³ |
| Lapse rate | 1.98°C/1000 ft to tropopause |
| Tropopause ISA | −56.5°C / FL360 |
| Pressure lapse | 27 ft/hPa (MSL–18 000 ft) |
| Density alt | PA + 120 × ISA dev |
| Temp correction | 4% per 10°C ISA dev |
Lapse rates & stability
Section titled “Lapse rates & stability”| Rate | Value |
|---|---|
| DALR | 3°C/1000 ft |
| SALR | 1.8°C/1000 ft |
| ELR (avg) | 2°C/1000 ft |
| Cloud base | (T − Td) × 400 ft |
Stable: ELR below SALR. Unstable: ELR above DALR. Conditional: SALR below ELR below DALR.
Wind rules
Section titled “Wind rules”Fronts quick sequence
Section titled “Fronts quick sequence”| Warm front | Cold front | |
|---|---|---|
| Slope | 1:100–150 | 1:10–80 |
| Clouds | Ci, Cs, As, Ns | Cu, Cb |
| Precip zone | 200+ NM ahead | 50–100 NM behind |
| Speed | ⅔ geo wind | Full geo wind |
| Pressure | Fall → steady | Fall → sharp rise |
Jet stream heights
Section titled “Jet stream heights”| Jet | Typical FL |
|---|---|
| Arctic | ~200 / 400 hPa |
| Polar front | ~300 |
| Subtropical | ~400 |
| Equatorial (summer NH) | ~450–500 |
Fog summary
Section titled “Fog summary”| Type | Key requirement |
|---|---|
| Radiation | Land, clear, calm 2–8 kt, night/early AM |
| Advection | Warm moist over cold surface, wind to 15–20 kt |
| Frontal | Warm rain into cold air ahead of warm front |
| Steam | Cold air over warm water |
METAR essentials
Section titled “METAR essentials”TS & icing avoidance
Section titled “TS & icing avoidance”| Hazard | Avoidance |
|---|---|
| TS (below FL200) | 10 NM |
| TS (above FL200) | 20 NM |
| Overfly | +5000 ft minimum |
| Severe icing | Divert / change immediately |