Point of No Return (PNR)

Point of No Return (or "Point of Safe Return")

Formula:

PNR = SE x H / (O+H)

SE = Safe Endurance (= endurance - final reserve)
O = groundspeed out
H = groundspeed home

PNR is a time calculation meaning that the answer will be a time. If the distance to PNR is asked, just use the simple "D=VxT" formula where speed (V) is the groundspeed out.

Find windcomponent to calculate GS

When a course is given together with the wind direction and speed, we first need to obtain the longitudinal wind component (headwind or tailwind) before we can convert TAS into GS.

Method 1 (quick formula): Windspeed x Cos(wind direction - true course)

Method 2 (navigation computer):

- Put course on top, turn wind scale to the wind direction
- Shift so that the line of the TAS intersects with wind speed
- Ground speed for that leg (OUT) can be read inside the circle
- Do the same but now with the opposite course to find the GS for the opposite leg (HOME)

Questions on Point of No Return