Chapter

14

Point of Safe Return (PSR)

Introduction								259
Derivation of the Formula . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . .	260
Transposing the Formula to Navigation Computer								261
The Effect of Wind on the Location of the PSR								261
Single Leg PSR								262
Questions - Single Leg PSR . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . .	263
Answers - Single Leg PSR . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . . .	265
Derivation of the Formula for Variable Fuel Flows .	. .	. .	. .	. .	. .	. .	. . . . 266
Example Variable Fuel Flows PSR - Single Sector . .	. .	. .	. .	. .	. .	. .	. . .	266
Questions - PSR with Fuel								267
Answers - PSR with Fuel . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . . .	268
Questions - All Types . . . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . .	269
Answers - All Types . . . . . . . . . . . .	. .	. .	. .	. .	. .	. .	. . . .	270

257

14 Point of Safe Return (PSR)

(PSR) Return Safe of Point 14

258

Point of Safe Return (PSR) 14

Introduction

Figure 14.1 Point of safe return

The POINT OF SAFE RETURN (PSR), previously referred to as the POINT OF NO RETURN (PNR), is the furthest point along a planned route to which an aircraft can fly and return to the departure airfield, or departure alternate, within the SAFE ENDURANCE of the aircraft. SAFE ENDURANCE is the length of time an aircraft can fly without consuming the mandatory reserves of fuel that are required overhead its departure airfield, or departure alternate, in the event of the aircraft returning from the PSR. This SAFE ENDURANCE, quoted as a period of time (or an amount of fuel) is used to calculate the PSR. It must not be confused with the TOTAL ENDURANCE, the time an aircraft can remain airborne, at the end of which the tanks are empty.

If the state of the weather, runway, let-down aids or political situation at a destination airfield is likely to deteriorate and the only recourse would be to return back to the departure airfield, or departure alternate, it is prudent to calculate a PSR. Normally, the calculation of a PSR would only be necessary for flights to an “isolated destination and no adequate destination alternate exists”. Occasions on which a PSR may be required might include flights from mainland airfields to destinations such as Easter Island, Cocos Island, Tahiti, Ascension Island and the Azores.

In flight, at a reasonable time before the ETA for the PSR, the pilot checks that the destination airfield’s weather, landing aids and runway state are acceptable for a period of usually one hour before to one hour after the destination ETA.

The distance OUT to the PSR equals the distance HOME from the PSR. The time OUT to the PSR and time HOME from the PSR will be the same in zero wind; if there is an overall wind component the time OUT and time HOME will be unequal. But, in each case, the two values total the Safe Endurance time.

Point of Safe Return (PSR) 14

259

14 Point of Safe Return (PSR)

Derivation of the Formula

(PSR) Return Safe of Point 14

Figure 14.2 Derivation PSR formula

260