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captain420

Flight planning questions, how to know how much fuel, OAT, flaps, to use?

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I have a question. For those who fly tube liners like the 777 either by PMDG or Flightfactor on X-Plane.

 

For example lets say I'm doing a flight from KLAX to RJTT, how do I know how much fuel I need to load, what flaps to use for take off and landing, what my OAT temp should be for take off, and what flight level and cost index to use? 

 

If I use TOPCAT, will that get all the info I need in order to correctly punch it into my FMC before departure?

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For OAT use what is commonly called the "normal lapse rate" of -2^C per thousand ft of altitude (using the surface temp in ^C as a baseline).  Ex. you plan to cruise at FL330 and the surface temp at 1,000 ft MSL is 20^C.  The altitude difference is 32,000 ft.  32 times 2 = 64.  20^C minus 64^C is then -44^C.  That is what you should anticipate for OAT at FL330.

 

Many aviation weather web sites provide winds aloft forecasts which often include anticipated temps at each altitude.  Of course then you should be using one of the available flight simulation weather engines that inject real world weather into your chosen flight simulator.  Without that the issue is not valuable for discussion.

 

The answers to the rest of your questions are highly dependent on the aircraft you are using, the barometric pressure and  surface level (from mean sea level) of the runway from which you are taking off from, again the surface temperature, the wind speed and direction, the aircraft you are flying and it's fuel burn parameters, and the loaded weight of that aircraft, including your fuel load (weight).

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All except the fuel to use in in the FMC performance page. You can even use the FMC to determine the fuel to use by entering all the data and viewing the progress page to determine how much fuel to use. There are also a few online fuel calculators that work good enough for what we do.

 

http://fuelplanner.com/

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Well what I want to know is, Will TOPCAT be able to figure out all this information for me, so that I wouldn't have to do calculations and what not? I'm trying to find a simplified and quickest process to figure out all this stuff.

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For example lets say I'm doing a flight from KLAX to RJTT, how do I know how much fuel I need to load, what flaps to use for take off and landing, what my OAT temp should be for take off, and what flight level and cost index to use? 

As a licensed dispatcher, I would follow all the steps that I learned in class, bearing in mind that this would take well over two hours to do, so it's probably not something you want to do if you're just flying along. The other option is to pull up the range charts for the aircraft and roughly calculate the fuel based on the range of the flight and the weight of the aircraft. As for flap usage, that could depend on how heavy you are, outside temperature, and how long the runway is if I remember correctly. Flight level depends on which direction you're flying and how heavy you are. Westbound is an even flight level, and eastbound is odd. As for cost index, that's down to airline preference.

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Topcat is designed to work out takeoff weights, V-speeds and Derates.

 

PFPX is designed to work out how much winds, weather, diversion holding and reserve alternates, enroute fuel burn etc is on the route.

 

Topcat has a very basic "fuel calculator" which is to be used when PFPX isn't.

PFPX does not have any V-speed/Derates calculator.

 

If you have both PFPX and Topcat, you should use PFPX first to determine the flightplan and fuel required.

Then you export this data to Topcat and run the V-Speed/Derates stuff.

 

Always use the same data in both of these programs and your FMC. If you tell PFPX that you are going to depart at 0300z, in an aircraft with 157 passengers, 3000kg of bags & cargo, with cost index LRC, but then when you get into the flight simulator, you depart at 1000z in an aircraft with 135 passengers, 6200kg of bags and cargo, and a cost index of 25, then your fuel plan usage and optimum altitude will bear no relevance to your PFPX flightplan.

 

Make the aircraft match PFPX, or make PFPX match the aircraft, either way they have to match. (And the departure time too if you are using ActiveSky! the REAL ACTUAL departure time, not a simulated offset night-is-day departure either! PFPX doesn't care what your simulated time zone is set to, it cares about when you are really flying your real flight really compared to the real clock in Greenwich London. The weather changes all the time, and it has to match as close as possible for it to work. PFPX has access to around 30 hours into the future of wind/weather forecasts.)

 

Many airlines use only one or two sets of flap settings by SOP.

 

B777

Light takeoffs - Flap 5.

Heavy takeoffs - Flap 15.

 

Landings Flap 30 unless heavy, where the flap 25 is used if the flap 30 vref is higher than the flap 25 vref.

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