(a) time and distance to the point of no return (PNR)
The Point of No Return (PNR) is the greatest distance that an aircraft can proceed and return to ADEP with the required reserve fuel.
After passing the Point of No Return the remaining fuel will not be sufficient for a return to the point of departure.
The flight can only be continued to ADES or to an alternate airfield.
To have a quick look at how to calculate your Point of No (safe) Return, lets consider a flight from Auckland to Norfolk Island a Distance of around 580nm. And the aircraft TAS is 200 kts and 4 Hours safe endurance.
No wind
In a no-wind situation it is easy it is the PNR point is just half of your endueance which is 2hours. 2hours at 200kts = 400nm.
Auckland to Norfolk Island
(Nil Wind)
Leg
Distance
@ Ground Speed
= Time
Auckland – PNR
400 nm
200 kts
2 hrs
PNR – Auckland
400 nm
200 kts
2 hrs
Total Time
4 hrs
We loose out when we have wind in to the situation which we always seem to have.
By checking the 1 and read off a percentage distane a long your track where the ETP is. This a handy check, to double check the ETP has moved toward the wind .
As Double Check, just confirm that the times for each legs are the same.