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Guest robdebakker

cabin altitude

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When climbing with the PSS 777-200LR to FL410 or higher I get an warning for cabin altitude. Speed drops then.Can not find anything in the docs and in this forum.Who can help?Rob

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What is the meaning of the warning "Cabine Altitude"? And why can't I keep up the speed at FL410?Is there anything about this and the warning in the documentation?Thanks,Rob

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Rob,At a guess, without more info I would imagine that FL410 is higher than you should be at that time. What is the max in the FMC for that stage of flight?The warning is that once you go higher the aircraft systems are unable to keep the internal pressure under specified minimum, that is to say even though the aircraft is at FL 410 internally it is as if you were at for example 8000 feet.

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Hallo Norman,The preferred FL is between FL409 and FL450 in the MCP CRZ page.Rob

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Hello,Check the DELTA PRESSION, the way I think it is is when above a certain delt P, the system in FS does not give more and the cab alt is at or over max.As 410 is the service ceiling, I would not be surprised.Cyrille de LattreAsus P4P800/PIV 3 Ghz/2 Giga DDRAMATI X800 GT 256 MegWin XP SP2 / FS9.1 PSS Beta tester

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Hello I do not know where PSS got the information that FL410 is the service ceiling for the 777 According to Boeing Manuals the service ceiling is 43100feet The cabin altitude warning sounding at FL410 is another bug I hope it will be corrected on the patch Cabin altitude at FL410 should not be more than 10000 if the system is modelled correctly it should be around 8000ft Best RegardsMauricio

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Mauricio is correct on the Boeing statement for 777 service ceiling. Moreover, service ceiling is nothing to do with pressurisation performance

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>I do not know where PSS got the information that FL410 is the>service ceiling for the 777 Mauricio,Whilst I stated FL410 it was, for want of a better term, an assumption by *me*. I've never had a need to take it higher.

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After 2 hours at FL423, I decided to find the limit. At FL425, no problem. At FL426, I get Rob's Cabin Altitude warning and - Lo and Behold - the pressuristaion monitor appears on the RH EICAS [you know, the one that disappears when you press "EXE" on the CDU after inputting your route!] This shows that cabin alt has exceeded 8500 ft - hence the warning and the need to do something.If I then descend to FL 425, the cabin altitude slowly decreases until as it reached 8500 ft, then the cabin altitude warning goes out and the pressurisation monitor on the EICAS disappears again.I know that the disappearance of this pressuisation monitor is mentioned in the sticky - but I wonder now if this is how it has been programmed to work. Although it really would be more effective if it was programmed to be available permanently, the crew would see an earlier warning that something was going wrong.As always, the intricacies of this incredible add-on continue to fascinate me.John R

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Flying EGLL-TXKF again to research the pressurisation system. I am half way across and cruising at FL432 with no problems (I stopped here as this is the official service ceiling). Unfortunately I could not find anything on the pressurisation system in the manual so had a look at the system controls on the panel. Above FL420, I found that I needed to change to manual pressurisation

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John,As soon as I can get back to a machine with Acrobat writer I will look and ammend the docs if needed.

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Thanks Norman. A very minor point but interesting all the same.John R

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Yeah, i had this warning the other day...my dad who is a 777 F/O for COA came in and showed me how to manually change the cabin altitude...but the DP was still at 9.0 or higher...which he said shouldnt have been....so i descended back down to fl380...and then climbed back up to 410 and everything seemed to go back to normal...and yes, the service ceiling for the 777 is about 43000...and flying at 41000 in the 777 is common, i in fact have flown with my dad in the cockpit on a ferry flight once and we were at fl410 the entire route...best of luck with your problembrian

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You wrote:>and showed me how to manually change the cabin altitude...but the DP was still at 9.0 or higher...Where and how do you change it, and what is DP?Rob

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RobSee the controls around bottom right on the overhead panel. DP = differential pressure between cabin and ambient.John R

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Do I push or pull it?And where can I read the altitude and DP.Thanks for helping,Rob

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RobPut the two outflow valves to manualUse the two open/close switches to move the valves to achieve the necessary cabin pressurisation whilst maintaining a safe DPRefer to the air conditioning data at the bottom of the the upper EICAS

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Hey John. Nice to see you putting on your test pilot cap. :)Jeff

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Hi, JeffSomething I was always interested in - but I went to fly Phantoms instead.Best WishesJohn

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