Point of Equal Time | Revised

Question 1

Define PET

Answer 1

The point of equal time, in its simplest form, is that point on tract from which it will take the same time to continue to the destination or return to the departure point.

PET does not take account for fuel.

Question 2

How to calculate distance to the PET in nm?

Answer 2

GSR / (GSO + GSR) x Total Distance

Question 3

Define CP

Answer 3

The critical point is very similar to the PET and is often referred to as a PET with one engine inoperative. The CP is calculated so that in the event of the loss of one engine, the pilot will know in which direction to fly in order to land the aircraft in the shortest time possible.

Question 4

Was is the key difference between CP and PET?

Answer 4

When calculating CP, we use a reduced groundspeed for calculating the distance. Note, when calculating the time to the CP, use the normal groundspeed.

Question 5

Define PNR

Answer 5

The point of no return is the furthest point an aircraft can fly away from the airfield of departure and return to that airfield, within its safe endurance.

Question 6

Does one include reserve when calculating the PNR?

Answer 6

No, PNR is calculated without using reserve fuel.

Question 7

Define the PNR formula

Answer 7

Time to PNR in minutes = GSR / (GSR + GSO) x endurance( minus reserve)

Question 8

When calculating the PNR, PSR or CP what if one important thing to remember regarding ground speed calculation?

Answer 8

When calculating the groundspeed using the flight computer, remember to calculate both the GSR and GSO groundspeed. GSR TAS is not simply just minus the GS0 wind velocity, calculate both separately.