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Guest MACAULA2

FMC Max Alt Message

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Hello ChapsI'm using Felice Valante's 747 Fuel Planner and FSnav to calculate my flight plans and fuel loads, however after 30 mins of flight time - on or around achieving cruise level - the FMC displays a message saying "MAX ALT FLXXX". In some instances, engine number 3 has then shut down and I have had to re-start it.At the same time, the Autothrottle dis-engages and SPD/THR or THR REF disappears from the AFDS. At first I couldn't figure out how to re-engage the throttle but have discovered that this can be done by pressing the VNAV button on the MCP until SPD appears in the AFDS.For example, today I was flying from KLAX to PHNL with 120,120lbs ZFW and 163,400 lbs starting fuel, cruising at FL350. 40 minutes in I was at FL350, the FMC VNAV page was displaying the ACT ECON CRZ page with a CRZ ALT of FL350 with an optimum flight level of FL347 and a PHNL landing fuel of 47.5. Suddenly the FMC dislayed MAX ALT FL126, and the Autothrottle diengaged.Why? If i've done everything correctly, the fuel load is correct, the plan is correct. Once at cruising altitude I normally select 8x normal speed. Could this be it?Any input would be appreciated.Regards, Captain Mac

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Could be the 8 X. I read somewhere that the max for the PMDG 747 was 4 X.Try repeating the exercise with 4 X max and see what happens.CheersSteve

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Thanks for thisI forgot to mention that it was intermitent so that could be it.

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