I have skimmed through other reports relating to the above topic but can find nothing similar so I thought I should report it here.In a flight (still ongoing) from VRMM (Male) to OMDB (Dubai) I had reached cruise altitude in the -800 when suddenly a message flashed on the FMC scratchpad to the effect that I had insufficient fuel. There had been no indication at all this may be the case and in fact I had boarded fuel using the excellent fuel planner (my thanks to the author).I pulled up the FMC and checked the estimated fuel at OMDB and found it to be 1.4. I was startled at this and watched for a minute or two then suddenly the FMC values changed to 7.4. I can assure anyone reading this that it is not a case of mistaken reading - it definately changed.I am loathe to call this a bug as I have seen the passion with which the PMDG bird is defended - and rightly so as it is a great add-on. However, I will call it as I see it say something was not quite right here. For what it is worth, that was nearly 45 minutes ago and since then a good boot up the rear (tailwind) has resulted in a fule saving.RgdsAndy b

Andy,I vaguely remember a thread about this a week or so ago. If I recall correctly, the issue was related to using time compression to speed up the flight. Once back on normal (1X) time, the FMC eventually recalibrated. Not sure if that's your problem, but maybe it's some help.Keith

I notice this same things on really long flights. It seems to plauge the first 1/4 or so. What my understanding (perhaps flawed) is due to the range of some of these flights a small change in engine thrust(say 2% N1) can hypothetically alter fuel consumption significantly if maintained. I believe the FMC calculates fuel by current thrust settings. So when the FMC gets around to recalcutating fuel consumtion(every couple of seconds), it takes your current thrust settings and calculates burn. Now say it calculates the burn when just 1 second prior the A/T increased its thrust because there was a wind gust. The fuel consumtion calculations now think there is a problem. However, when the fuel is recalcualtes a couple of seconds later(after the engine spooled back a bit), the fuel is calculated to be much more normal and safe.Again, that is my hypothetical understanding of what is going on. I could be wrong. The bottom line is that unless the message stays on for half the flight, your fuel will be fine.

actually I recall PMDG stating that this would be addressed in the 800/900 release. I seems like this may not have been done.The light should come on if your predicted fuel at dest is below your entered CDU reserve fuel entry. Also, this indicator is specifically inhibited during certain times (i.e. TO thrust setting, weight on wheels, ect). There are a few spurious times this light comes on the this product. It may be a hard one to nail down.

Hi!ad FMC-Message:I encountered the same Probs as some of you. I figured out that it has to do with my Weathertool (AS2004). Everytime the weather changes (especially Windchange), the Autopilot corrects the thrustsettings to maintain the set speed. if i get strong headwinds, then you need temporary more thrust to move speed up to the set level. the fmc calculates continously and you get the insuff. fuel msg. until the speed and thrustsettings are in normal conditions again.My Problem is another one.Ive encountered heavy Problems with the Fuelconsumption of the -800. I made 4 flights now and every time i had the problem that i used too much fuel. So what have i done:I planned my route with FS-Build to get my Distance between Dep. and Dest.-Airport. Next i used the Table from the PMDG-Manuel to determine the Fuel needed for this Trip. Then i made the fuelplanning like it is described in the Manuel (gratz to this very good manual!).For example i made a Flight from LEIB to LOWW with LOWL as alt Destination. The planning with FS-Build got me a Routelengh of 1215 NM and 95 NM to alt. Dest.Well, based on this data i started to calculate like in the Manual.For 1215 NM at FL370 i need 174 mins for that trip and 13858 lbs of fuel. Due good Winds (light winds from behind) there was no need to correct the fuelplanning with winddata, so i went to the next step - calculate the fuel for the alt dest. From LOWW to LOWL the trip is 95 NM. 95 NM at 14000 ft need 2145 lbs of fuel and 21 mins of flight time. Ok now i have my fuel to alt dest. Now i added the holding Fuel (2000 lbs), the Taxifuel (1000 lbs), and the minimum landing Fuel (1800 lbs). If i add all these data in my calculatian i will need 20803 lbs Fuel overall. If now my flight to LOWW went without any problems i use the trip fuel + the taxifuel which is 14858 lbs. So when i have 20803 lbs on board and i have a nomral flight i use 14858 that should leave 5945 lbs left in my tanks when i touch down at loww.At my touchdown i had about 3900 lbs left in my tanks, which means that i used 2000 lbs too much:(. 3900 lbs i entered in the fmc as reserve which is calculated with the minimum fuel + alt. dest. fuel 1800+2145 lbs = 3945 lbs. So anywhere on the flight i lost my complete holding fuel of 2000 lbs:). Maybe i have done something wrong and i hope that is so:) - pls explain what ive done wrong:).Thx anyway for this wonderful plane. I love to fly it and its the first plane whith a manual with flighttechniques - great job guys.happy landingsChristian Gullneritzp.s.: and pls excuse my english:) i know its not the best hehe!