PET AND PNR | FP&P

Question 1

How will flying into the affect the PET?

Answer 1

Flying into the wind will set the point of equal time beyond the half way point. Since returning will take less time due to the tailwind.

Question 2

Define the PET formula

Answer 2

GSR(Ground Speed Return) divided by GSR + GSO(Ground speed on) multiplied by the total distance from point A - B

Question 3

Does the PET take account for fuel?

Answer 3

No, PET does not account for fuel.

Question 4

Define “CP” and the relevant formula

Answer 4

CP is the critical point, or is often referred to as the point of equal time with one engine inoperative. CP calculation will be similar to the PET except:

1. That we will use the reduce TAS for both our groundspeeds (GSO & GSR).
2. To calculate time to the CP, we will use our full TAS.

Question 5

Define PNR and the relevant formula.

Answer 5

PNR is the “point of no return” or the “point of safe return”, it will be the furthest point an aircraft can fly away from the airfield of departure and return to that airfield, within its safe endurance, ie without using reserve fuel.

GSR divided by (GSR + GSO) multiplied by the endurance( in minutes) = Time to PNR/PSR in minutes.

1. Remember to use safe endurance(total endurance minus reserve)
2. Remember to use minutes when calculating PNR/PSR.