Originally Posted by
Windy Militant
A few years ago I bought a Book at the PFA rally entitled 'Diversion Planning' (using only a stopwatch and a pencil) this gives lots of Handy Tips. It's based on RAF methods and as the author Martin Smith says if it's good enough at 400Kts it's good enough for GA. Other diversion planning books might be available.
An interesting viewpoint that.
400 knots, 25 knot crosswind, drift is about 3½°
100 knots, 25 knot crosswind, drift is about 14½°.
The first is within most people's accuracy to fly anyhow, and should deposit you within sight of your destination. The last could put you well into controlled airspace, danger areas, and very likely not in sight of your destination if drift planning isn't done properly.
Me? Flight computer, compass, chart and stopwatch like I was taught years ago. No flight computer? draw a rough triangle of velocities on the chart and use that.
G