Fuel planning

[PKlijnstra]

"Hi guys, Yesterday I had a flight from LEMD to KORD but I had to make an fuel stop at St.Johns CYYT due to insufficient fuel message from the FMC. Is there any formula to plan your fuel amounts? Thanks,"

[Brogs]

"Peter What was your Fuel Reserve setting within FMC, if you have it too low the FMC gives you a message that you have insufficient fuel.which is not alway,s the case, I think in the REAL world , Pilots set it at either 24000 or 20000. As for fuel planning, for the 742 there is a fuel planner which you can download and the 744 & 744f have Loaders that give you the Fuel Estimate when you Load the Aircraft and then you can inrease that amount upto the Max illustrated based on your GTOW and any contingencies you think may arise . Safe Landings , Mike"

[PKlijnstra]

"Thanks Mike, my fuel reserve was 6.6, so 6600lbs. I put this all the time. That's not the problem because the progress page showed me that I was halfway out of fuel already. As for for the loader, it will not give you an fuel estimate because it shows you allways 6800lbs, at least in my loader. You still have to guess how much."

[maj]

"You know, the FMC does a pretty good job calculating the amount of fuel you will need to make a trip. Usually on west bound trips I load enough fuel so the FMC calculates 30-40K remaining on arrival. This number will be less because you will have head winds when westbound... therefore on landing there is about 20-30K remaining. As for going eastbound, I load enough to get 20K remaining. That will be greater on arrival because of the tail wind. As for reserves, I set mine to 15K in the FMC. I read somewhere on this forum that landing with 20K was most desireable, so that's the figure I shoot for. My 2 cents worth..."

[eek]

"For the 744, I've found a method that works pretty well. I use a combination of the dispatch release form, here on the GC website and a fuel planner from the Avsim library called fuelplanner_v2.01.zip by Felice Valente. The GC planner is for the 742, and tends to under estimate needed fuel. The 744 Fuel planner is for the pax version of the PMDG, and tends to over estimate. First I run the GC dispatch planner, and note the fuel load it gives. Then I run the 744 fuel planner. The planner gives you variable inputs. For miles, I use the total from the FS Navlog. Enter the winds and initial FL you expect, your cargo and Contingency Time (I usually use 30 minutes). Enter Minimum landing fuel - 19000 for short flights, 24000 for long hauls, then hit calculate. The fuel load it gives is often higher than the GC, but not always. Then I just split the difference. If the GC says to load 210000 and the 744 planner says 260000, I load 235000. For the reserve, I just use the method straight out of the PMDG manual. Min. landing fuel + alternate airport fuel + 1/2 of contingency fuel. I use the numbers straight out of the boxes in the 744 planner. So, for a 3000 mile trip with 30 minutes contingency time and an alternate airport 100 miles away, your reserve should be 32 (32000). I know this method isn't exactly scientific or realistic, but since we don't have an accurate planner to use, this is the best I have been able to come up with. I've done nearly all my GC flights this way, and I've never had to make an unexpected landing or jettison fuel to get under max landing weight. As Mark said, the FMC is quite accurate, but the drawback is, it doesn't consider winds. On a long flight with a strong head/tail wind, it can be off by as much as 30000 lbs., by the time you reach your destination. So, if you plan fuel based on a strong tail wind, you're likely to still get an insuffuicient fuel message. In that case, you can lower it to 24 or 19 to clear it. You shouldn't have to go lower than that. Realistically, you don't want to go lower, in case you get to your destination and it's below minimums. If you are heavy with cargo, doing a very long long flight, or just want to be miserly with the virtual fuel, you can enter your values in the INIT REF-PERF page, then flip to page 2 of VNAV and see what your calculated landing fuel will be (also good for finding out what your optimum initial FL should be) and tweak the fuel load as necessary, based on expected winds. (Just be sure to do it before you fire up the pirep prog.) Once you get a handle on how winds effect your fuel burn, you can pretty much nail your ideal landing weight. Again, not necessarily scientific or realistic, but it's quick, simple and it's worked well for me."

[esurfman]

You can also use the method described in the PMDG manuals. Takes longer but is more accurate.

[PKlijnstra]

"Thanks for your replies guys, I think I can make sense of this "