Measuring chart distance
Distance = track line length x chart scale, converted to nautical miles.
- Read scale off the chart.
- VNC: 1 cm = 500 000 cm = 5 km ≈ 2.7 nm.
- 1 NM = 1 minute of latitude (TP 1102): read off the latitude scale at chart side. 1 degree = 60 minutes = 60 NM.
Estimate without a protractor (TP 1102):
- 10 mile marks pre-drawn on track line
- Thumb-and-finger span or knuckle span held against scale
- Pencil marked in 10 mile increments
Trap: distance left in kilometres or statute miles, not nautical; or wrong chart's scale read.
References
- TC AIM MAP 2.5.1 (VNC 1:500 000 scale)
- TP 1102 (one minute of latitude = 1 NM)
- AC 100-001 glossary (nm = 1.852 km, nm = 1.152 SM conversions)