The active rw should be the thing where the AI planes take off and land. They choose their stuff depending on the winds.
As a test, load your plane at EGLL, set the weather manually and watch the guys changing the active runway. If this doesn't work, something else may be wrong.

Current METAR 2011/10/03 23:50 EGLL 032350Z 25009KT 9999 BKN011 17/14 Q1019.
So if you would use rw weather right now, you should see rw27 operations in the sim unless they aim for 8 kts of tailwind on the 09 ones, which I doubt.

There would be a way of limiting the departures and arrivals to certain runways in FSX, but I don't think that the scenery you spoke of has those limits implemented. This wouldn't make sense.
The real Heathrow has a sort of rotation in place, so they actually use some runways even with tailwind components up to a certain level (I would have to look up the values though) for noise abatement reasons and stuff.

The thing that I dislike about Orbx YMML AU is using the crosswind capability when the wind is calm, ALL runways are in use so you and the AI aircraft takeoff from the nearest one and, if landing there, you can approach straight in from any direction. This makes the ATIS message huge when it means ALL ILS approaches as well as visual. It even seems to mention runways that I can't even find there! It's crazy.

Mark

Poor Peter's computer crashed an his iPad's touchscreen keyboard is inhibitive, because my 'Apple magic keyboard' isn't being magical...

There is a slight chance that Peter is in the "mix up mode" when it comes to runway headings, wind directions and favourable departure routes.

The KLAX departures offer procedures for every runway direction of course, but the noise preferred departure routes are over the ocean, for obvious reasons. So westbound departures are indeed common practice as far as I can see.
If the tailwind component goes above 10 kts, they seem to switch their westbound preference though. Again, obvious reasons.
The planned destination in regard to the departure direction should only matter in the very short route regime, e. g. on the TEC routes.

However, how did your St. Maarten approach work out, boeing247?   Shocked tourists or some which enjoyed the show?

CoolP wrote on Oct 4^th, 2011 at 12:46am:

For the sake of improving framerates I have played with the settings and so I have turned that OFF sometimes. Especially when the wind is calm.
I really should have said "The thing that I dislike about Orbx YMML AU is that when using the crosswind capability and the wind is calm, ALL runways are in use so you and the AI aircraft takeoff from the nearest one and, if landing there, you can approach straight in from any direction."
Just another simple misunderstanding.

Mark

CoolP wrote on Oct 4^th, 2011 at 2:18pm:

If I'm flying an ultralight, I do not need to be flying around in a thunderstorm! So I don't always use ASE weather!

CoolP wrote on Oct 4^th, 2011 at 2:33pm:
No. I only did it that one time and the J3 was like a chopper. It went up vertically and I flew at the same speed as the wind (~45 knots) so it was like I was hovering and when landed, I went straight down, sometimes slightly backwards, until I landed. I "hovered" for about five minutes!