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hi, i tried today for 1st time, to use the vnav, following the tutorial (from cold and dark state). when i press vnav i get the msg perf/vnav unavaible. for me, i did everything right. in my demo flight i created, the only "strange" is the very short flight, lgsa to lgav, at 11.000 alt at a distance of 144nm. i used fuel 55.000 (25.000 for the flight in safety) plus 30000 for the wings as the example says. i put right the temperatures for takeoff (27c that moment +15 , plus a little more) 55 in total. trim also calculated 5.7 and put. v2 of 153 also at the spd ready. i dont know what else it could be. i read many times the tutorial example and there is nothing different. any ideas pls?

thank you

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11 minutes ago, thenikos said:

i get the msg perf/vnav unavaible

...but then:

12 minutes ago, thenikos said:

i did everything right.

Clearly, you did not.

This is the second time I'm seeing this kind of statement, and I'm kind of baffled as to the logical leaps required to get here. If what you wrote - that this is the first time you're using VNAV - you are therefore, I'm guessing, somewhat new to the concept of VNAV itself, and the requirements to use it. If this is the case, then it would not be too unexpected to be surprised by forgetting, or not noticing, certain things. Learning new things always has a few trips and falls here and there. To assert that you're doing it correctly, when you're new to a concept - all while there is evidence (things not working correctly) - that you're not doing it correctly, however, is odd to me. Nobody gets points for getting it right on the first try. You don't get points removed for showing up somewhere and saying "hey, I'm pretty sure I'm doing this correctly, but I might not be - here's what I'm seeing - any ideas?"

In fact, I'm more willing to help people who will come in with that attitude, rather than "VNAV Problem" (asserts VNAV is the problem, and not user error), and "I did everything right." I'm not saying that to be mean; rather, I say that to point out that, if I'm going to help someone, the former shows they're willing to learn, while the latter somewhat indicates that the person is sure that the problem lies elsewhere. That might be the case, but to be honest, errors are usually found in the human part of the equation. Code, being written by humans, can be subject to that, sure, but it's prudent to look inward first, before looking to place blame elsewhere. After all, if it were truly a VNAV issue, there'd be a ton of posts about it from a ton of people seeing the same issue, no?

14 minutes ago, thenikos said:

i read many times the tutorial example and there is nothing different

Reading and doing are very different things.

14 minutes ago, thenikos said:

any ideas pls?

PERF INIT page. Top left entry. Is there an arrow next to the number, like "<533.2" ?

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hi scandinavian and thanks for your reply. of course i didnt say it is a pmdg problem. otherwise i wouldnt ask what i forgot or what i did wrong. thats also i said maybe it is the low altitude? or the short distance? i am the problem thank you for telling me 🙂

as i also stated i started the plane in dark and cold. the example on the tutorial is based on the default condition. thats why i also asked if i forgot something (to switch on i mean) that is related with the vnav.

and to your question: no, there is no arrow, just the gr wt value of 552.7 for me.

 

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hi again: i found a mistake comparing to the tutorial: i didnt put reserve fuel. at the tutorial it says that this entry is purely advisory. i left it empty and vnav didnt work. now i put a value and vnav works. do you think that was the reason?

thanks

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3 hours ago, thenikos said:

when i press vnav i get the msg perf/vnav unavaible. for me,

If you are seeing this message then you have definitely not completed the initial loading of the FMS correctly.

As Kyle has said, pilot input is the issue (sorry, but that means you!) and not the QOTS's VNAV.  I suggest you double check each tutorial step from the beginning, starting with the Index page.  A good general tip is to use the 6R Key when each entry page is completed, so that you can then go to the next FMS page in turn until you have finished entering all of the data correctly for your flight. 

Make sure you have also activated the three calculated FMC PERF speeds in the FMS too and remember to check them again if you change any performance information, otherwise VNAV won't work,  You won't be able to arm VNAV prior to takeoff if you haven't loaded the FMS correctly.

Bertie G       

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3 minutes ago, thenikos said:

hi again: i found a mistake comparing to the tutorial: i didnt put reserve fuel. at the tutorial it says that this entry is purely advisory. i left it empty and vnav didnt work. now i put a value and vnav works. do you think that was the reason?

thanks

As you have now discovered, you have to fill in all of the 'boxes'!   Enjoy the steep learning curve and remember it helps if you always follow the tutorials carefully first - read twice and input once!

Bertie

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berts i never said it was plane's problem !! 🙂 ******* !!! i clearly said i was sure something i forgot 🙂 or did wrong. or didnt switch on.

in our case if the reserve is mandatory to make vnav work, then it was the tutorial fault not mine 🙂 it said the entry is purely advisory. there should be written that in case you dont fill it , vnav will NOT work 🙂 so people like me (yes i know bad ones who accuse the plane), would put the entry from the beggining.

saying good night, i made a test flight with vnav and is ... amazing 🙂 what i was missing so long time i didnt use it 🙂

thank you all for your help !!! 

ps. im sure i will ask more stupid questions in the future because just now i found time to read the 2500 page (in total) manuals 🙂 so i do experiments on what i read.

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10 minutes ago, thenikos said:

thank you all for your help !!!

You're welcome!!!  Good luck with the tutorials and happy flying, because the QOTS B744 is amazing.

Bertie

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