Presentation on theme: "Critical Pts & Pts of No Return ATC Chapter 5. Aim To identify operational considerations for flight planning, and demonstrate the use of calculating."— Presentation transcript:
Critical Pts & Pts of No Return ATC Chapter 5
Aim To identify operational considerations for flight planning, and demonstrate the use of calculating Critical Points & Points of No-Return
Objectives 1.Define the Critical Point 2.Demonstrate method of Critical Point 3.Define the Point of No-Return 4.Demonstrate method of PNR 5.Summary of the above
1. Define Critical Point What is a Critical Point? Also known as Equi-Time Point - ETP It is the point between departure & destination where it would take the same amount of time to proceed to destination or turn back. DestinationDeparture 45min Critical Point In nil wind where would the critical point be? In the middle! If there is wind, this will move the critical point into wind.
1. Define Critical Point What is a Critical Point? DestinationDeparture GS Home GS OUT Critical Point Total Distance
1. Define Critical Point How is the CP derived?
2. Use of the CP Method YMIAYPPF GS Home = 100 kt Critical Point = 87.5nm from YPPF Total Distance = 210 GS out = 140 kt
2. Use of the CP When can we use this? Flights over water Flights in remote areas Long distance flights Diversions due to weather Increase in situational awareness
3. Define the PNR What is the Point of No-Return? Also known as PNR, it is the point where there is insufficient fuel to return to departure aerodrome with reserves infact. The calculation is crucial on flights where aerodromes are limited such as remote areas or water destinationdeparture PNR Beyond this point, if the aircraft turns back it will not be able to land with reserves infact
3. Define the PNR Considerations? The PNR is independent of the CP, as PNR is fuel consideration. The PNR will always be beyond the CP, because at the CP there must be fuel to either proceed or return, this is not the case with the PNR Any wind will reduce the dist to the PNR as in a tailwind due extra fuel burn to return, and in a headwind due extra fuel burn to go against wind destinationdeparture PNRCP
3. Define the PNR How is the PNR derived?
4. Demonstrating PNR Planning method destination departure PNR GS out =200kt GS home =160kt Wind +20kts tail
4. Demonstrating PNR Practical method
4. Demonstrating PNR Practical method – Engine failure destination departure PNR GS out =150kt GS home =150kt Wind – 30kts head
4. Demonstrating PNR Practical method – Climbing considerations If climbing, take into account the fuel used in climb/descent. Eg: Outbound TAS = 180kts, fuel flow 100lt/hr, total fuel 516lt, wind 30kts tailwind outbound Engine failure TAS = 120kts, fuel flow 60lt/hr Climb fuel = 20lt & 35nm How far from departure is the PNR? Fuel available for PNR = 516 – 90rsv – 15taxi – 15%vbr = 358 Lt for flight Subtract the climb & descent fuel Descent (approx) = (0.667 x 35nm) = 24lt 358 – 20lt climb – 24lt descent = 314 lt for PNR 277nm + 35nm = 312nm from departure aerodrome destination departure PNR GS out =210kt GS home =90kt Wind +30kts tail 20lt 35nm 277nm
4. Demonstrating PNR Practical method – Enroute Enroute made from a positive fix & similar to the climb/descent, subtract the outbound/inbound fuel. Eg: Outbound/inbound TAS = 180kts, fuel flow 100lt/hr, total fuel 516lt, wind 20kts tailwind outbound Positive fix = 80nm from departure How far from departure is the PNR? Fuel available for PNR = 516 – 90rsv – 15taxi – 15%vbr = 358 Lt for flight Subtract outbound & inbound fuel outbound (approx) = (0.5 x 80nm) = 40lt Inbound (approx) = (0.588 x 80nm) = 47lt 358 – 40 – 47 = 271lt for PNR from fix 249nm + 80nm = 329nm from departure aerodrome destination departure PNR GS out =200kt GS home =170kt Wind +20kts tail 40 lt 80nm 47 lt 249nm
4. Demonstrating PNR Summary of PNR destination departure PNR Cruise out & back PNR for planning destination departure PNR Cruise out return asymmetric (lower alt) destination departure PNR TopC Planned PNR out & return with climb/descent TopD destination departure PNR Outbound fuel Inbound fuel Inflight PNR out & return from positive fix
5. Summary Summary of PNR vs CP/ETP The distance to the PNR depends on the flight fuel available Changes to reserves, variable reserves, holding, airwork etc Distance to the CP/ETP is independent of flight fuel. The only time fuel is to be considered is if the pilot wishes to know how much fuel will be burnt passed the ETP Once past the PNR the aircraft will not be able to return to the departure airport with full reserves/fuel intact If the aircraft returns to departure at the ETP he/she will have reserves & excess fuel intact