I always use the PMDG Cold and Dark, and follow the complete procedure from FCOM.

 

Try a different panel state and let us know how that works.  There's an issue with the C&D state.

I think I've caught the issue red-handed. I was flying with same route and same plane setting as before. The only difference was the panel state (as scandinavian13 suggested). Instead of C&D I used the default state I get when the sim is loading. But that was still not the case.

Time/Fuel from the FMC:

Taxi Out - 1639Z-> 33.0

Climb - 1639Z-> 1212Z/32.0

T/C - 1651Z-> 1212Z/31.6

1741Z-> 1212Z/31.5

1834Z-> 1212Z/24.8

1957Z-> 1212Z/24.4

2021Z-> 1212Z/24.2

Just before S/C - 2059Z-> 1213Z/24.1

After S/C - 2105Z-> 1213Z/24.0

 

An then it happened.

I had my view set on the FMC, when the sim froze. It does happen to me every once in a while (several times during every flight). It is a known issue, listed in the PMDG 777 issue tracking thread ("Long pauses where the sim recovers after 30 seconds to a few minutes.").

Anyway the sim was frozen at 2115Z, and the FMC said 1213Z/24.0. Then the sim recovers, 2116Z at the clock. I look at the FMC, and it says 1213Z/17.7!!!

 

So it seems like during those pauses, the sim, the time and everything is frozen but for a fuel flow! Nothing changed in the conditions, there was no weather at all, I haven't changed any settings. I haven't checked the fuel qty before and after the freeze, but I think I would see 6300 lbs less fuel. It would be very weird if the freeze changed just the prediction. That also explains why the predicted  fuel amount sometimes decreased by few hundred lbs in an hour, and sometimes by several thousand.

 

So I think I have found an issue.  Most likely the issue will be gone with resolving the 'freezing issue'. Can someone re-track my thinking and see if my conclusion is correct?

Tis true that the fuel does drop when those pauses occur in my experience but my experience of those pauses has been once.

 

It is happening to me when these pauses do not occur. It seems most of the time. I have been factoring for this and adding more fuel than is predicted. At the moment I am on route from Brisbane to Hong Kong in the freighter and when I left the prediction was of 16.2 on arrival. I am now half way and it is predicting 12.6

 

This time I have been monitoring the predicted winds in the FMC imported from AS2012 with what the aircraft is experiencing and the the difference so far is almost non existent.

 

It seems to me as if the FMC got its numbers wrong on the ground somehow. Or something else is at play.

 

Just dropped to 12.5

 

I have not yet managed to bring myself to do a long haul with no weather yet but I may have to just to eliminate.

Try doing the same flight with CLEAR WEATHER. There are no winds to increase/decrease fuel burn.

 

I suggest people are not properly flight planning, and are failing to adequately check the Met. Remember, all values are predictions or approximations. Actual weather en-route may vary. No refunds. Terms and conditions apply. May not be used in conjunction with any other offer or promotion. :rolleyes:

 

Best regards,

Robin.