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Oliver Gates

Random increase in VAS usage over Iceland or Greenland

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Recently, I was flying the PMDG 777 from EGLL to KSFO (flight BA285/BAW11M), and my route took me ever so slightly south of Iceland and over the southern part of Greenland. After leaving the west coast of Greenland, I received a high VAS warning from FSUIPC, and I realised that my VAS usage was at 94%.

This was significantly higher than I would have expected, and - eventually - I got an OOM error (my first one in Prepar3d V3). I honestly can't figure out what caused it; P3D handles VAS very well, and I have flown this flight once before with exactly the same scenery and settings, and there were absolutely no issues.

The only difference between this flight* and my previous flight** is that this flight's route took me much closer to Iceland (further north). Therefore, I can only think of three possible causes:
1) Something in Iceland led to an extremely significant increase in VAS usage (in spite of the fact that I don't own any scenery in Iceland);
2) Orbx recently updated the Orbx Libraries, and this was related to whatever caused the OOM error;
3) I flew over Manchester, and UK2000's EGCC caused a dramatic increase in VAS usage (which I find difficult to believe).

I am aware that Orbx have a free Iceland demonstration product; however, I have never installed it.

I would like to emphasise that the VAS usage when I flew this flight previously was nowhere near 94% when I was leaving the west coast of Greenland, and all of my scenery and settings were exactly the same. The only difference (as far as I am aware) was the route.

Thank you for taking the time to read this; I would be very appreciative if anyone could provide a possible explanation for this seemingly random increase in VAS usage.

Cheers,
Oliver


*This route (with an OOM error):
WOBUN UL10 DTY DCT SAPCO UN57 TNT UL28 PENIL UL70 BAGSO DCT ERNAN DCT BALIX DCT BREKI DCT 66N040W 66N050W DCT EPMAN NCAE YYN J530 GTF J7 LKT DCT LLC J32 FMG J94 ECA RISTI4

**Previous route (without an OOM error):
WOBUN DCT WELIN UT420 TNT UL28 RODOL UM65 TENSO UL603 REMSI DCT DIMLI DCT GINGA DCT GOMUP DCT 61N020W 63N030W 65N040W 66N050W DCT EPMAN NCAE YYN J530 GTF J7 LKT DCT LLC J32 FMG J94 ECA

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Platform?  Full name?

 

I have the Orbx England, Scotland and Canadian/Alaska products and have flown several trips recently over or near Greenland, most recently the EGLL-KDFW AAL trip.... no problems with VAS. I've not overflown Iceland.  Using P3Dv3.3.5 and ASN B6610. All sessions are now full screen with much fewer issues with VAS than windowed mode.

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I honestly can't figure out what caused it

KSFO has problems with memory leakage on approaches to certain runways because of the missed approach procedure. Maybe you used a different runway for the second flight. See post #91 on page 7 of this thread - http://www.avsim.com/topic/477686-p3d-v3-fmc-memory-leak-back/page-7. You might have used the same runway for both flights but time compression enters into this issue also. If one flight used compression - no problem. If the other one didn't use compression - between Greenland and Canada sounds about right to have an OOM.

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Good possibility, Michael.  I've started to not select the approach until I'm at the 100 nm before TOD point where weather and pre letdown checks start.  It's not unrealistic to defer that selection and it avoids the possibility of the VAS problem due to leakage.

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Good possibility, Michael. I've started to not select the approach until I'm at the 100 nm before TOD point
Either that or delete the missed approach in the SIDSTARS folder in the KSFO.txt file. Delete everything after RNW 28R in this approach - APPROACH ILS28R FIX CEPIN AT OR ABOVE 3000 FIX AXMUL 1800 RNW 28R HDG 284 UNTIL 420 TRK 251 INTERCEPT RADIAL 281 TO FIX VIKYU FIX VIKYU AT OR ABOVE 3000 HOLD AT FIX VIKYU RIGHT TURN INBOUNDCOURSE 281 LEGTIME 1. I do it both ways. Both methods work fine.

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I've experimented with routes from various European cities to KSFO, and I can routinely

summon up an OOM somewhere over the north Altantic simply by having RW28R entered as the arrival runway.

 

Editing the AIRAC data, as mentioned above seems to work but is fiddly. The best method method of avoiding OOMs is to only enter your

arrival runway close to the ToD.

 

Airports with this OOM issue and the 30-degree radial / memory leak issue that I know of  are KSFO, KSEA and VHHH.

There are others, but these are the ones that give me issues on my normal routes.

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