In-flight calculating of Depressurised ETP fuel required

Transcription

1 Copyright Avfacts ETP fuel page 16. In-flight calculating of Depressurised ETP fuel required General: These will probably be worth 5 marks in the ATPL exam. You will be expected to read the question and understand your present position on an ERC chart, identify the given position of the ETP, and calculate the minimum fuel required to be on board at the fix to proceed on to the destination or alternate airport, assuming loss of cabin pressure at the Depressurised ETP. You will assess fuel burn from the fix to the ETP at normal ops cruise level/speed, then the fuel from the ETP to landing assuming a cruise level of FL130. Finally, you will add the minimum fuel reserves to arrive at a minimum fuel on board (FOB) at the fix for the operation. Remember that for IN-FLIGHT Dep ETP s the only reserve required is 2, 250 kg of fixed reserve. Do NOT add any final taxi, holding or variable reserve fuel. Reserve fuel for IN-FLIGHT ETP depressurised is: V/R Fixed Reserve 2, 250 Wx Hold Initial Taxi Use the winds/isa deviations at FL185 for the FL130 level. A worked example of a typical ATPL type ETP minimum fuel question follows.

2 Copyright Avfacts ETP fuel page 17. In-flight ETP Dep min fuel required Example 1. A B727 is in-flight, enroute from Darwin (YPDN) to Alice Springs (YPAS) on ERC H1 route A461. Cruise Sched: M 0.82/FL330. BRW YPDN was 76, 000 kg At 1440 UTC the position is: 230 nm from Darwin, maintaining Mach 0.82/FL330. Operations are normal! Tail wind 52 kt/isa +6. Aircraft GW at 1440 UTC is 72, 460 kg. The ETP depressurised is calculated as 316 nm from Darwin, and assumes a RETURN to YPDN at FL130, or continuing ON to YPAS at FL 130 if the cabin pressure is lost enroute. Airport weather: Darwin is ACCEPTABLE, becoming SUITABLE if holding fuel to cover TEMPOrary deteriorations below alternate minima is carried. Alice Springs is ACCEPTABLE becoming SUITABLE if holding fuel is carried to cover INTERmittent deteriorations below alternate minima. Additionally, 15 minutes traffic holding, and 15 minutes WIP requirements are current. Fcst RSWT data FL ISA YPDN/YPAS Using the actual wind/temps being experienced at FL330 for the cruise segment out to the ETP Dep, and the forecast wind for all other levels, what is the minimum amount of usable fuel which must be on board at the 1440 UTC fix to allow for depressurised operations between Darwin and Alice Springs?

3 Copyright Avfacts Working: ETP fuel page 18. Step 1. Find forecast wind component/isa dev at FL130 ETP/YPAS. In this case it is TWC36 kt/isa +7. Step 2. Calculate distance from fix to ETP Dep (86 nm), and distance ETP Dep to YPAS (384 nm). Step 4. Find descent distance into YPAS. In this case it is 13 min/520 kg/58 gnm. Step 3. Draw flight profile and show distances/ wind components/isa deviations. Step 5. Calculate from 1440 UTC fix to ETP, and fill in normal ops cruise data including for that zone. Step 6. Find aircraft GW at the ETP. Step 8. Add up the zone s plus the 400 kg circuit fuel at YPAS to get flight fuel from 1440 UTC fix to landing YPAS. Add reserves (2, 250 kg fixed reserve only for in-flight depressurised situation). Step 7. Calculate from ETP to TopD YPAS, and fill in Dep ops cruise data for that zone including. Flight Fuel 5, 458 V/R Fixed Reserve 2, 250 Wx Hold Min FOB at Fix 7, 708 kg Answer! FL330 Winds/Temps 52 kt/isa +6 Darwin 230 gnm 1440 UTC fix GW 72, 460 kg Mach kt 534 kt FF 4, 498 SGR T 86 gnm 727 kg Flight profile ETP GW 71, 733 kg Mach kt 412 kt FF 4, 817 SGR T 326 gnm 3, 811 kg 13 min 520 kg FL130 TWC 36 kt ISA gnm YPAS 400 kg

4 Copyright Avfacts ETP fuel page 19. In-flight ETP 1 Eng Inop min fuel required Example 1. A B727 is in-flight, enroute from Alice Springs (YPAS) to Brisbane (YBBN) ERC H1 routes T11/G326. Cruise Sched: M 0.79/FL330. At 1300 UTC the position is: 214 nm from YPAS, maintaining Mach 0.79/FL330. GW 70, 000 kg. Operations are normal! Tail wind 70 kt/ ISA +10. The ETP 1 Eng Inop is calculated as 498 nm from YPAS, and assumes a RETURN to YPAS at FL240, or continuing ON to YBBN at FL 230, if an engine fails enroute. Airport weather: Alice Springs is ACCEPTABLE becoming SUITABLE if holding fuel is carried to cover TEMPOrary deteriorations below alternate minima. Additionally, a 15 minute traffic holding requirement applies. Brisbane is ACCEPTABLE becoming SUITABLE if holding fuel is carried to allow for INTERmittent weather deteriorations. Additionally, a 15 minute traffic holding requirement applies. Fcst RSWT data FL ISA YPAS/NONET FL ISA NONET/YBBN Using the actual wind/temps being experienced at FL330 for the cruise segment to NONET, and the forecast wind for all other levels and zones, what is the minimum amount of usable fuel which must be on board at the 1300 UTC fix to cover 1 Engine Inop operations between Alice Springs and Brisbane? 1300 UTC fix From YPAS NONET 70 kt/ kt/+14 ETP 1 Inop Superzone average TWC/Temp from fix to ETP is 58 kt tail/isa kt/isa +16 TopD ON to YBBN at FL nm 90 nm 482 nm YBBN Normal Ops superzone wind/temp Zone distances

5 Copyright Avfacts Working: ETP fuel page 20. Step 1. Calculate distance from fix to ETP Dep (284 nm), and distance ETP Dep to YBBN (568 nm). Step 2. Find forecast wind component/isa dev at FL230 for zone ETP to TopD YBBN. In this case it is TWC 19 kt/isa +16. Step 4. Draw flight profile and show distances/wind components/isa deviations. Step 3. Find superzone wind from 1300 UTC fix to ETP. In this case it is TWC 58 kt/isa +11. Step 5. Calculate approx LW at YBBN. It is approx 60, 000 kg (rounded). Use this to find descent distance. Step 6. Find descent data into YBBN. In this case it is 18 min/610 kg/86 gnm. Step 8. Find aircraft GW at the ETP. Step 7. Calculate from 1300 UTC fix to ETP, and fill in normal ops cruise data including for that zone. Step 9. Calculate from ETP to TopD YBBN and fill in Dep ops cruise data for that zone including. Step 10. Add up the zone s plus the 400 kg circuit fuel at YPAS to get from 1300 UTC fix to landing YBBN. Add reserves, including whichever airport has the highest weather holding. In this case it is YPAS with 4, 000 kg (TEMPO). FL330 average Winds/Temps 58 kt/isa +11 YPAS 214 gnm 1300 UTC fix GW 70, 000 kg Mach kt 527 kt FF 4, 125 SGR T 2, 223 kg Flight profile ETP GW 67, 777 kg Flight Fuel 7, 963 V/R 796 Fixed Reserve 1, 500 Wx Hold 4,000 Min FOB at Fix Mach kt 426 kt FF 4, 181 SGR T 482 gnm FL230 TWC 19 kt ISA +16 4, 730 kg 18 min 610 kg 86 gnm 14, 259 kg Answer! FL kt 400 kg YBBN Now attempt the In -flight ETP minimum fuel requirements assignments 1 and 2.