Common Chart Scales
The scale of a chart gives the ratio of chart distance to real distance. 1
,000 means: 1 cm on the chart = 500,000 cm = 5 km in reality.Standard scales in aviation
| Scale | 1 cm chart = | 1 mm chart ≈ | Use |
|---|---|---|---|
| 1,000 | 2 km | 200 m | very detailed; partly Swiss ICAO chart; local approach charts |
| 1,000 | 2.5 km | 250 m | US Terminal Area Charts (TAC), some national ICAO charts |
| 1,000 | 5 km | 500 m | ICAO standard for VFR (Germany, France, Switzerland, Austria); US Sectional Chart |
| 1,000,000 | 10 km | 1 km | World Aeronautical Chart (WAC) — overview for cross-country |
| 1,000,000 | 20 km | 2 km | planning charts, continental overviews |
Scaling in NM (practical for PPL)
| Scale | 1 mm = | 1 cm = | 1 NM ≈ |
|---|---|---|---|
| 1,000 | 0.135 NM | 1.35 NM | 7.4 mm |
| 1,000 | 0.27 NM | 2.7 NM | 3.7 mm |
| 1,000,000 | 0.54 NM | 5.4 NM | 1.85 mm |
→ On an ICAO 1
,000 chart, 1 NM ≈ 3.7 mm with the plotter.ICAO 1,000 charts — the VFR standard in Europe
Conventions (ICAO Annex 4, complemented by national AIS):
- Lambert Conformal Conic projection, two standard parallels depending on region.
- Magnetic variation drawn as isogonals, with epoch year and annual change.
- Elevation tinting: layered colour bands (typ. green → yellow → brown → white) for topography.
- MEF (Maximum Elevation Figure): per quadrant, the highest terrain/obstacle point + 100 ft margin, rounded up, in thousand ft AMSL, placed at the quadrant centre.
- Airspaces: classes A–G with boundaries, altitudes, MAOC.
- Obstacles: masts, medium and radio towers, high-voltage lines (above a certain threshold; typ. > 100 m AGL).
- Aerodrome symbols: by surface (paved/grass) and visibility.
- Visual reference points: VRP (visual reporting points) with name.
Scale-specific rules of thumb
1,000 (most common VFR chart)
- 1 NM = 3.7 mm.
- Cruise speed 100 KTAS in no wind → 100 NM/h → one hour of flight = 370 mm = 37 cm on the chart.
- Small obstacles (high-voltage lines, transmitter towers) need not all be individually shown if below the threshold.
1,000
- 1 NM = 7.4 mm.
- More detail: smaller obstacles, smaller roads, more ground features.
- Good readability even for small airfields.
1,000,000 (WAC)
- 1 NM = 1.85 mm.
- Overview chart for long cross-countries, IFR planning, general route overview.
- Less detail; individual aerodromes possibly only a dot.
Chart selection
- VFR with visual flight on short legs: 1,000 — the mass ICAO chart.
- Complex TMAs with many small fields / obstacles (e.g. Swiss Mittelland, Munich TMA): partly 1,000 or 1,000 for additional detail.
- Cross-country > 200 NM or overview: 1,000,000 WAC or electronic moving map.
Currency
- ICAO charts are reissued annually (standard edition usually spring, often aligned with the AIRAC cycle).
- AIRAC cycle: 28-day cycle in which ICAO-relevant data take effect worldwide synchronously (see Subject 070 / 010).
- Outdated charts must not be used for VFR navigation — the requirement for a current chart is established in SERA.5005 / national VFR regulations.