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Given the following information, calculate the time from position A to the Point of Safe Return (PSR):

Distance from A to B: 2 346 NM
Ground Speed "out": 365 kt
Ground Speed "back": 480 kt
Safe Endurance: 8 hr 30 min

  • A
    209 minutes
  • B
    219 minutes
  • C
    197 minutes
  • D
    290 minutes

The Point of Safe Return (PSR) is the last point on a route at which it is possible to return to the place of departure, arriving back with required fuel reserves still available in the tanks.

The calculation of the time to reach at PSR is based on the helicopter's safe endurance (Total fuel minus the Reserves) and is given by the formula:

  • Time to PSR = (E x H) / (O + H)


  • E = Safe Endurance
  • H = Groundspeed Home (or Back)
  • O = Groundspeed Out

Thus, the Time from A to PSR is: (8.5 hr x 480 kt) / (365 kt + 480 kt) = 4.82 hr or 290 minutes.

The sector distance from A to B must be ignored. It is given just to confuse you with the Point of Equal Time (PET) formula.

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