VFR Navigation, rerouting timing corrections due to wind - rule of thumb?
If you know or have a reference to Ground Speed, estimating reasonably accurate flight timings is straightforward. Whatever your GS, you will cover 1/10th of the distance in 6 minutes. So at 90kts, 9 miles in 6 mins. At 70kts, 7 miles in 6mins and at 120kts, 12 miles in 6 mins etc. If you mark your pen/pencil with 5 &amp; 10nm distance marks measured in the same scale as your map, it’s easy to interpolate say, 7nm (for say 70kts GS) and mark your map with 6minute marks. If needed dissect these markings in half, for 3 minute markers.