Off-route Crit Points
I'm sure we're all happy with calculating the Crit Point on a journey from A to B. But what if there is an off-route airfield 'C' abeam the route? Does anyone know how to calculate a crit point along route AB for AC and then CB? Assuming one has all the required winds. At the moment I just use an iterative primary digital method (ie thumb along the map every 10 minutes until C slips past) but there must an elegant solution.