Time to PSR (Point of Safe Return)
The Point of Safe Return (PSR) is the last point on a route at which it is possible to return to the departure airfield arriving back with the required fuel reserves still available in the tanks. Continuing passed the PSR you are now committed to landing at your destination.

Time (to PSR) = E x H / 0 + H

• Where, E = Safe endurance based on available fuel; H = Ground speed home; O = Ground speed out

1) Calculate wind component using the following formula:
Cos (wind angle) x wind speed = Cos (285º) x 15 = approx. 4 kts HWD

2) Calculate Ground Speed from Departure to Destination - Ground speed out "O"
TAS - Headwind = 125 kt - 4 kt = 121 kt

3) Calculate Ground Speed from PSR to Departure - Ground speed home "H"
TAS + Tailwind = 125 kt + 4 kt = 129 kt

4) Apply the following formula:
Time (to PSR) = E x H / 0 + H
Time PSR = (3.3 x 129) / (121 + 129) = 1. 7 hr

5) To find the distance you have to multiply the time it takes to reach the PSR by the Ground speed Out = 1.7 x 121 = 205.7 NM