Hello Captains,Today I fancied a EGLL-KBOS online. I fired 'er up from cold and dark, loaded 237,000lbs of fuel from the PMDG menu, set up the FMC as usual and started taxiing. After takeoff, I engaged the autopilot and LNAV, but VNAV wouldn't engage. I took a look at the FMC and it gave me an Unable CRZ Alt error. Fine, I said, so I entered FL260 for Initial cruise instead of FL320. It still gave the same error. It gave the error even when I entered 3000ft as cruise altitude. I reloaded the same fuel or different amounts from the PMDG menu again with no change. Then I looked at the PROG page. It said that I would have -2,200,000lbs of fuel left at KBOS... WHAT? :)So I decided it was some kind of a fault of ground crew( ;) ) and turned back to EGLL. I tried to set up the arrival; but everytime I selected a STAR or a Runway for arrival, it gave PROGRAM ERROR. I thought it would be a Heathrow error with Navdata again, so I keyed in Gatwick EGKK, and tried the same thing. Still gave a PROGRAM ERROR! I ended up to dump my fuel and make a complete manual landing at EGLL. Has anyone else experienced anything similar? It seemed too bizarre for all of these to happen on one flight!Any ideas anyone? I have the Service Pack 1.1 (the LATEST 1.1) installed.EDITORS NOTE: Robin: Please be more careful with your headers.

Can't say I've had the exact same issue, but on a few occassions I've had the "PROGRAM ERROR" message appear on the FMC. Sorry I can't be more specific about what I'm doing when I get the message, its been a while since it last happened - but it has happened.What I can say however, is that it has happened to me pre the Service Pack 1.1 update.Cheers,Steve.

Same problem here Robin, only happens every now and then, before AND after Service Pack 1.1

Robin, I encountered the exact same problems on my very first 747 flight a few days ago. Wasn't sure what was wrong, but restarted, and I've made about 5 flights since then without any problems.

Hi Robin,I find that reloading the fuel in the PMDG fuel menu solves this problem for me.

Guys,Next time you see something like this, could you immediately save the flight and email the relevant files to us?

I just reinstalled the Service Pack and it seems to be fixed. I'll let you guys know :)

>Guys,>>Next time you see something like this, could you immediately>save the flight and email the relevant files to us?Ryan, my problem isn't cured (except for the PROGRAM ERROR) and I seem to be getting it with every flight. I've sent you an e-mail to the support [at] PMDG address stating exactly what happens.

I got the PROGRAM ERROR when trying to input a STAR in a flight from KSEA to KSFO last night. I have the flight plan saved but not the flight. I never took off so I don't know if I would have had any of the other problems.Cheers,Erichttp://www.precisionmanuals.com/images/forum/747400.jpg

Gents,Errors of this type may more often than not be attributed to specific procedures as coded in the SID/STAR/IAP files. Some procedures are automatically generated others manually written. A badly written procedure may drive the math in the FMC crazy.We are grateful to all those that write/produce such procedure files since the vast majority of these make this hobby a joy and our simming life easy. On the other hand PMDG is not responsible for any few badly/inappropriately written such proc files and any problems related.I would suggest checking your flightplans when this happens and act accordingly.Best,Vangelis===================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com=====================================