Point of No Return
Calculate point of no return and equal-time point for a route with wind.
What is the PNR?
Point of no return is the point on a route beyond which there is not enough endurance to return to the departure point. Equal-time point is where the time to continue equals the time to return.
Wind affects both points. A tailwind outbound can move the PNR farther away, while the ETP shifts according to the relative groundspeeds in each direction.