Yet another "Insufficient Fuel" problem...

[oskrypuch 36]

>Hi,>>I had this problem a couple months ago when I flew from EGLL>to KSFO. I received the message on the gound during taxi>(strange), and yet I knew I loaded the correct amount of fuel.> I use the same fuel planner as you, and I wasn't quite sure>why I received the message. The even stranger thing is that>after I took off, and got into CRZ, I checked the FMC, and it>showed plenty of fuel at landing. So, either it was an>anomoly, or I did something wrong that I couldn't see.>>- John>You can get this crop up, but more often when you are flying west to east.The scenario is that you have used FSB with AS6 wind inputs to calculate a fuel burn, and there happens to be a significant tailwind to the flight.You will have on board less fuel then you need to make that flight, if there was no tailwind.The FMC doesn't know about the tailwind (unless you tell it), and will assume that you don't have enough fuel. That assumption is not valid, because there is a tailwind! Hence your erronenous INSUFFICIENT FUEL FMC messages. If you ignored them, you would find that your projected fuel at your destination would keep climbing, and you should get there just fine with good reserves.How to avoid this? Just tell the FMC about the tailwinds. In the LEGS page, hit the RSK buttons beside a few of the flights waypoints, and put in the forecast wind from AS6 at that location.Problem solved.* Orest

[cowpatz 243]

Hi Ben,Sorry i forgot all about looking that up in the ops specs. Flying to LAX tomorrow so will look then. It may or may not be there as some of this stuff would be delegated to our performance and flight planning personnel who then develop a policy.Alternates for SFO are OAK (tech alt), FAT and LAX.Enroutes for the 777 are the same as the 747. For the end pairs it would be either ITO or HNL and SFO or OAK. Others on the way up are dependant on the route direction but can include NAN, PPT, APW, HNL, ITO or KOA.Dont think you will see me on NZ 8. In a few weeks I will be heading off on our new AKL/HKG/LHR service. Should be interesting!.Cheerssteve

[phil747fan 14]

hello all,as we are talking about dispatch im here too ....far is giving something jar for europe another one and then canada one intersting stuffsfor alla commercial flight under CAR 705 is due to have 5% reserve, 30 min hold at 1500 ft and an alternate airport with minimun depending on existing runways equipment .... but depending where the aircraft is going no need for route reserve or altn ....uh i said complicated .....see you

[Guest benhoffman]

Thanks Steve, I'm getting the grand tour of Ops & Dispatch the day I head out so I'll be sure to ask tricky questions :)Remember to head up Kalwoon on the cable car, you get great views of HKG city and the airport & the old checkerboard.Phil, yes, got to love all those complex aviation regulations and the complicated exemptions given to the airlines by the regulators, I hear American (AA) has some interresting ones.

[ukflight 11]

An interesting thread and well worth the read. However as a point of note in case anyone is inclined to copy and paste the cfg entryfor FSB the NATRAKURL line is incorrect - it should be NATRAKURL=http://www . fsbuild.com/nat.html (without the spaces)

[Guest egll]

Hi There....I haven't read any of your replies, so i'm not sure if your sorted. But, I had the same problem on the 747 Queen. My flight was from Heathrow to Toronto. Just over 3000nm. Now I don't use fsbuild, so maybe it creates the same error, but although my fuel load was correct, I too was getting an 'Insufficient Fuel' message. Then I noticed that one of the waypoints that was in the FMC was incorrect. (The software is used to create the flightplan had a bug in it, and occasionally caused this to happen). It was the 1st waypoint after takeoff, was showing as 4125nm away, which was further than my whole flight, whereas the waypoint I should of had (Same name) was only 16nm away. After some FMC re-programming, the route was sorted and the Message was gone....Hope This Helps......egll

[johndrago 4]

There is a checkbox in the fuel>planner with the text "Enable fuel burnout correction for>deviation abovebelow 475000lbs landing weight". When checked,>I get 78348 lbs. more fuel in the "total fuel load" (giving me>over 875000lbs GTW, so I have to throw out some of the>passengers ;)). I remember checking this box in my other long>haul flights, possibly explaining the "insufficient fuel">message I got yesterday, but I honestly have no idea what this>does to the calculation. I've added two pictures showing the>fuel calculation before and after checking this box. I hope>someone can tell me what effect this checkbox has.Sorry guys that I'm bringing up an old note, but I have been doing research lately on fuel burn, and never found out why the fuel planner by Felice Valente has the option noted below. Did you ever find out what the "Enable fuel burnout correction for deviation abovebelow 475000lbs landing weight" option does, and should it be enabled for every calculation?When enabled, quite a bit more fuel is added to the total fuel load. Sometimes the planner is right on, and other times, I'm way short. And I account for headwinds. I'm probably doing something wrong, but I'm not sure what.Thanks,John

[michal 44]

>Did you ever find out what the "Enable fuel burnout correction>for deviation abovebelow 475000lbs landing weight" option>does, and should it be enabled for every calculation?It is obvious what it does. And yes, it should be enabled all the time. Michael J.

[johndrago 4]

>>>Did you ever find out what the "Enable fuel burnout>correction>>for deviation abovebelow 475000lbs landing weight" option>>does, and should it be enabled for every calculation?>>It is obvious what it does. And yes, it should be enabled all>the time. >>Michael J.>Thanks, would you mind explaining it to me so I understand?- John

[Guest D17S]

You're right. It's not obvious, but here's my best guess . . . It seems the author pre-set the flight planner to always use a landing weight of 475,000 lbs. As long as the box is unchecked, the planner will set the fuel load so this will be your landing weight. Seems to me that a trip's payload and fuel contingency requirements will be so variable that planning fuel on the basis of a preset landing weight doesn't make any sense at all. Therefore, set the check box so the planner calculates a burn number based on a variable landing weight.It appears what is happening is that the planner is adjusting the initial fuel load so it will cause the landing weight to always be 475K. If this is the case, the fuel load will have nothing at all to do with the projected burn. The planner is only using the fuel load to create a preset landing weight. When you finally input the flight plan into the airplane's real FMC (very quietly and behind the scenes), the FMC calculates a zero wind fuel burn. Your FMC knows what is going on. But when you load up the planner's fuel load, the FMC says (essentially) "Now what are you doing? I don't get it." If it's more than needed, it just stays quiet. Hey, you're the boss. But if the fuel load is not sufficient to make the trip (remember the FMC already has this number pre-calculated), it saves your life, or in its own business like way annunciates "insufficient fuel." Sure wish Matts luck with his flight planner. That's what we really need. 'Til then, just use the FMC for your fuel burn calculations. It already has the burn number. The PMDG 744's FMC is Still going to be the very best fuel planner available.

[johndrago 4]

>You're right. It's not obvious, but here's my best guess . .>. >>It seems the author pre-set the flight planner to always use a>landing weight of 475,000 lbs. As long as the box is>unchecked, the planner will set the fuel load so this will be>your landing weight. Seems to me that a trip's payload and>fuel contingency requirements will be so variable that>planning fuel on the basis of a preset landing weight doesn't>make any sense at all. Therefore, set the check box so the>planner calculates a burn number based on a variable landing>weight.>>It appears what is happening is that the planner is adjusting>the initial fuel load so it will cause the landing weight to>always be 475K. If this is the case, the fuel load will have>nothing at all to do with the projected burn. The planner is>only using the fuel load to create a preset landing weight. >>When you finally input the flight plan into the airplane's>real FMC (very quietly and behind the scenes), the FMC>calculates a zero wind fuel burn. Your FMC knows what is going>on. But when you load up the planner's fuel load, the FMC says>(essentially) "Now what are you doing? I don't get it." If>it's more than needed, it just stays quiet. Hey, you're the>boss. But if the fuel load is not sufficient to make the trip>(remember the FMC already has this number pre-calculated), it>saves your life, or in its own business like way annunciates>"insufficient fuel." >>>Sure wish Matts luck with his flight planner. That's what we>really need. 'Til then, just use the FMC for your fuel burn>calculations. It already has the burn number. The PMDG 744's>FMC is Still going to be the very best fuel planner available.> Thanks Sam, I appreciate it! It makes sense now.- John