Fuel Problem - 777-300ER and PFPX

[Enno 0]

Hi,

 

I have a strange Problem with the T7, together with PFPX:

 

In PFPX I created a Route from Kathmandu VNKT to Auckland NZAA. Simply the Route, no further flight planning. A total distance of about 6.426,5 nm.

 

In P3D I loaded the 777-300ER simply with 100% of fuel. Some passengers, some cargo, but in total way below MTOW. Weather with ASN. The FMC kept telling me I had Insufficient fuel for the trip, so I didn't start the flight.

 

Then I did a test, searched for a Route via rfinder (total distance 6.441 nm, so slightly longer) and fed the FMC manually. Same Airport, exactly the same payload, same total amount of fuel, same time of day, same weather. But this time my FMC told me I would have a remaining amount of fuel of more than 40 t on board at the time of my arrival.

 

How can this be? That a shorter PFPX created Route gives me less remaining fuel than a manually inserted one under the same circumstances?

 

Always happy landings,

 

-Enno

[VH_JLC 1]

Check your way points, it could be a database mismatch, switch the efis knob to "plan" and the corresponding fmc to "legs" and cycle through your trip.

Sometimes there's a way point in the northern hemisphere with the same name as one in the south..

 

Hope it helps

 

Josh

[Enno 0]

Hi Josh,

 

I had checked it. But also the FMC told me the distance to my destination was only 6427nm, so it was correct. In both cases -PFPX as well as rfinder- the distance calculations of the FMC matched the distances the planning tools pointed out. The only difference was that after importing the route from PFPX the FMC told me completely full tanks were not enough...

[scandinavian13 5,192]

Hi Josh,

 

I had checked it. But also the FMC told me the distance to my destination was only 6427nm, so it was correct. In both cases -PFPX as well as rfinder- the distance calculations of the FMC matched the distances the planning tools pointed out. The only difference was that after importing the route from PFPX the FMC told me completely full tanks were not enough...

 

PFPX assumes wind. Your FMC assumes no wind until you tell it there will be wind, thus the error.

[Enno 0]

Ha, this is an interesting hint. I will investigate in this direction. Thank you very much for the help! :-)

[scandinavian13 5,192]

Ha, this is an interesting hint. I will investigate in this direction. Thank you very much for the help! :-)

 

Welcome! Let us know how it goes! If you have ASN, there's a procedure in Tutorial #1.5 that makes the weather import function really simple.

 

Just to let you know: full names - first and last - are required here in the forum.

[Enno 0]

Okay, I'll update my profile. But - Enno is actually my real first name... :-)

[scandinavian13 5,192]

Okay, I'll update my profile. But - Enno is actually my real first name... :-)

 

Cool - thanks for updating that!

[Enno 0]

One last question before I start testing/ investigating: What kind of weather would pfpx assume here? For I just created a route, a "bundle of waypoints" with some airways (I didn't do any weather related flight planning in any kind) - would this mean PFPX exports weather information to the flight route file automatically, without any order/ influence from my side...?

 

I thought I had just created the route, nothing more...

[scandinavian13 5,192]

 

 

One last question before I start testing/ investigating: What kind of weather would pfpx assume here? For I just created a route, a "bundle of waypoints" with some airways (I didn't do any weather related flight planning in any kind) - would this mean PFPX exports weather information to the flight route file automatically, without any order/ influence from my side...?

 

PFPX will download current, real world weather for the scheduled/estimated time of departure that you give it. Automatically.

 

 

 

I thought I had just created the route, nothing more...

 

That would kinda defeat a lot of the purpose of the program itself.

[77west 139]

I ran that same flightplan in PFPX but said no weather and got this:

 

FUEL CORR ENDUR

TRIP 113144 ........ 13:15

CONT 5% 5657 ........ 00:51

ALTN 3079 ........ 00:22

FINAL RESV 3312 ........ 00:30

HOLD 1678 ........ 00:15

MIN T/O 126870 ........ 15:13

EXTRA 0 ........ 00:00

TAXI 340 ........ 00:10

RELEASE 127210 ........ 15:23

 

then same but with live weather and got:

 

TRIP 108755 ........ 12:16

CONT 5% 5438 ........ 00:48

ALTN 3090 ........ 00:22

FINAL RESV 3370 ........ 00:30

HOLD 1706 ........ 00:15

MIN T/O 122359 ........ 14:11

EXTRA 0 ........ 00:00

TAXI 340 ........ 00:10

RELEASE 122699 ........ 14:21