744X power loss

[Ton8t 0]

I have had this problem show up twice. After making a step climb once to FL370 the second time to FL390 the plane just seems to lose power airspeed drops down to around 150knots even tho N1 is still showing over 90% auto throttle and speed hold were on off on off several times. The ac won't hold altitude no matter if I use alt hold, vnav or flch. I am currently flying from Dubai to Hong Kong, I had to make an emergency landing at Mandalay Myanmar. After l landed and shut down everything except APU, I started up again and now it seems to be working fine, the only difference is I have left continuous ignition on the entire flight. Is continuous ignition needed at high altitudes.BTW, I have the registered version of FSUIPC with smoothing set as per a forum thread I read here.Thanks,Rick Faulk

[jobepilot 7]

I have had this problem show up twice. After making a step climb once to FL370 the second time to FL390 the plane just seems to lose power airspeed drops down to around 150knots even tho N1 is still showing over 90% auto throttle and speed hold were on off on off several times. The ac won't hold altitude no matter if I use alt hold, vnav or flch. I am currently flying from Dubai to Hong Kong, I had to make an emergency landing at Mandalay Myanmar. After l landed and shut down everything except APU, I started up again and now it seems to be working fine, the only difference is I have left continuous ignition on the entire flight. Is continuous ignition needed at high altitudes.BTW, I have the registered version of FSUIPC with smoothing set as per a forum thread I read here.Thanks,Rick Faulk

Hi RickWhats the weight of plane fuel etc, and whats in the VNAV page for max alt ???? You cannot just climb this plane from TO to FL 370 or FL390 if not planned properly due to weight. If you can provide more info I can help. But normally on Long Haul step climbs are used. Also whats the air temp

[FLEX1978 373]

I have had this problem show up twice. After making a step climb once to FL370 the second time to FL390 the plane just seems to lose power airspeed drops down to around 150knots even tho N1 is still showing over 90% auto throttle and speed hold were on off on off several times. The ac won't hold altitude no matter if I use alt hold, vnav or flch. I am currently flying from Dubai to Hong Kong, I had to make an emergency landing at Mandalay Myanmar. After l landed and shut down everything except APU, I started up again and now it seems to be working fine, the only difference is I have left continuous ignition on the entire flight. Is continuous ignition needed at high altitudes.BTW, I have the registered version of FSUIPC with smoothing set as per a forum thread I read here.Thanks,Rick Faulk

Continuous ignition when in the air is only used in heavy rain or turbulance. Did you have a look at the TAT and SAT? high temps in crz cause a loss of performance, if your weather program is giving dodgy readings then the aircraft won't maintain alt.As I'm sure your aware, the aircrafts GW is a big factor in chossing your crz alt. You say you where step climbing so it sounds like you where using correct procedures.Just one last thing, the PMDG 744 seems a little too sensitive to high temps in Crz, I spent a lot of time flying from the middle east to hong kong last summer and had to divert quite a few times when over India, that is the only area on the FS Planet where I have seen this happen. No such problem during the other seasons.Rob

[Ton8t 0]

Hi RickWhats the weight of plane fuel etc, and whats in the VNAV page for max alt ???? You cannot just climb this plane from TO to FL 370 or FL390 if not planned properly due to weight. If you can provide more info I can help. But normally on Long Haul step climbs are used. Also whats the air temp

I was using step climbs as per the FMC. I climbed when the FMC said NOW on the Econ Crz screen page 2 of VNAV pages.

[jobepilot 7]

I was using step climbs as per the FMC. I climbed when the FMC said NOW on the Econ Crz screen page 2 of VNAV pages.

Yep sorry didnt read properly :(

[Ton8t 0]

Continuous ignition when in the air is only used in heavy rain or turbulance. Did you have a look at the TAT and SAT? high temps in crz cause a loss of performance, if your weather program is giving dodgy readings then the aircraft won't maintain alt.As I'm sure your aware, the aircrafts GW is a big factor in chossing your crz alt. You say you where step climbing so it sounds like you where using correct procedures.Just one last thing, the PMDG 744 seems a little too sensitive to high temps in Crz, I spent a lot of time flying from the middle east to hong kong last summer and had to divert quite a few times when over India, that is the only area on the FS Planet where I have seen this happen. No such problem during the other seasons.Rob

Well it started just east of India but it was at night, and the temp was about -18 and the tat was about the same. I was using default FSX weather with FSUIPC smoothing so I don't know about possible turbulence as FSUIPC smoothes all of that away.Rick

[jobepilot 7]

Well it started just east of India but it was at night, and the temp was about -18 and the tat was about the same. I was using default FSX weather with FSUIPC smoothing so I don't know about possible turbulence as FSUIPC smoothes all of that away.Rick

yep what Rob said, check out the weather it is a known problem

[Ton8t 0]

yep what Rob said, check out the weather it is a known problem

Thanks for the answers. I just completed the flight went on to VHHH with no problems. Turned the old non-stop into a one-stop.

[Ton8t 0]

I hate to have to reopen this but I am having a repeat of that problem. My speed hold is not holding. I'm now flying from VHHH to KLAX and about 2000 nm out from KLAX I start having the speed bleed off. I did all of my step climbs as per the FMC and even reduced altitude down to a lower FL. That worked for a while then I noticed that the stick shaker started buzzing and my speed was down in the yellow band of the speed tape. I manually throttled back up then reset the AT and speed hold. Now the speed slowly bleeds from .848 mach down to about .800 mach then slowly climbs and drops. Any idea what might be causing this.Thanks,Rick Faulk

[Ton8t 0]

Solved again. It was due to the downloaded weather not updating. Skin temp was +25C, which is impossible forced download of weather and it's all good now.