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1251452

777 VNAV perf unavailable

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Hello everyone,

I was flying from KLAX to VHHH and had loaded in a route before T/O. Everything was working fine until I saw that the route I had loaded was not the most efficient due to strong Pacific Winds. I went back to simbrief and reset a new route unchecking plan stepclimbs. When I went into the route page and requested a new route, everything loaded fine except for the VNAV data. The route was there and I could change the altitude in the VNAV cruise page, but none of the data was on the route. The Perf init page was still in order, but I couldn't arm VNAV. It kept saying VNAV perf unavailable. I searched this around a bit, but could not find a solution.

Thanks in advance!

(copied from ticket)

 

1251452


1251452-Matthew Tan

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Probably just a snag as this should happen only if the performance page is blank.

 

I would have tried to re enter the performance page data, hoping that would reset things.


Rob Robson

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All the perf data in the perf init is there, I tried adding constraints into the legs page, but nothing.  I think my mistake was that I entered straight into rte 1 a completely new route, when I should have loaded into rte 2 then made active.  I sent pmdg a support ticket, and that's what they said to do.

Thanks for the reply,

1251452


1251452-Matthew Tan

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A basic concept to remember is that the current leg in the active route cannot be changed.  Also, the VNAV Perf Unavailable has very little to do with the PERF data page; rather, it simply means that the VNAV path prediction program is unable to calculate a solution based on the information you gave it.  The problem was more likely due a combination of things rather than just one.

 

It is okay to adjust the active route ahead of your current leg, which is something you would have to do in the B737 which doesn't have the RTE2 feature.  I recommend you make changes manually rather than trying to load a SimBrief generated plan for a flight enroute.  That's just asking for trouble.


Dan Downs KCRP

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Ok, lesson learned.  I will do that in the future.

 

Thanks for the replies,

1251452


1251452-Matthew Tan

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you can use a simbrief generated fpl file, u just have to enter the departure and make a direct to the next waypoint. then it calculates all the altitudesn and speeds

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