Scenery removes AI traffic?

[Guest jes-s]

I have installed Saba Island scenery (saba2004.zip) and the corresponding AFCAD file (af2_saba.zip), all files from the AVSIM library. When I only active the AFCAD file I have no problem in adding AI traffic to the airport. However, when I at the same time activate the Saba Island scenery I cannot get any AI aircrafts visible at the airport. To me it doesn't seem like an AFCAD problem, so what may cause the problem? The scenery?

[jvile 1]

Yes, Airport scenery plays a major role in the AI Traffic behavior.>at the same time activate the Saba Island scenery >I cannot get any AI aircrafts visible at the airportThat is because the AI Planes are sitting 115 ft. below the visual surface that you see.Many Scenery Designers do not design airport scenery with AI Traffic in mind but only design for the User Aircraft when visibility is severe clear (VMC) and flying VFR. That leaves alot of features out of what FS9 gave us over 2 years ago. If you have made a AFCAD that adds a runway black link line, start locations, unticked FS9's default runway closure, added parking spots, taxiway link lines, hold short nodes and several Comm freq's this does not assure you that AI Traffic will work properly in the 3rd party scenery.The designer built the airport on a 133 ft. plateau and did not consider that AI Traffic is working with a elevation of 15 ft which is the default elevation value. But then again it does not matter if the designers goal was for User Aircraft only and AI Traffic is not the objective for this airport. This type problem even plaques many Commerical/Freeware Scenery Designers that try and add AI Traffic to their Airport. That is because there is no approach data written to help in the aid of the AI Plane finding the runway. Other issues in this same area is when Designers add a new ILS with AFCAD or change the exsisting runway numbers which destroys the approach default data as seen with the GPS receiver causeing havoc for AI Traffic arrivals. Many 3rd party designed AI Plane FDE's are not written for the FS9 hard code that has to be used when there is no available Approach code. This can cause AI Traffic to fly into the ground long before they reach the runway theshold. Some of that is due to sink rates when gear and flaps are lowered. The AI Plane sinks with no recovery because the written hard floor altitude is missing along with a FAF the AI Plane sources from.The list goes on but one other major important incredent that must always be considered when designing a 3rd party airport is that the airspace up to 108SM/85NM in all directions is also owned by the airport scenery. Many never think past the airport boundry and do not consider the unseen scenery world that FS9/ATC works with.The good in all this is, it is fixable using several different methods/tricks in FS9 if the scenery has already been released.This statement posted by Reggie Fields on another related issue sums it all up"It kind of goes back to an old concept - do the scenery designers try to force Flight Simulator to conform to their wishes and fight against the program, or do the scenery designers take advantage of the capability built into FS and work with the program." hope this is helpful

[Guest jes-s]

>Yes, Airport scenery plays a major role in the AI Traffic>behavior.Thanks Jim for your detailed answer. I just tried to decompile the airport data (AP931250.bgl), change the airport elevation to the 133 ft, recompile it, and then add it with highest priority. However, this didn't work out :-(

[jvile 1]

If you decompile a default scenery which is not advisable you cannot add it to a priority. It must stay in the default Area/Region so FS9 can handle the priority.Here are some ways to correct the problem.1. Use JABBgl to change the airport elevation to match the 3rd party scenery. I personally do not recommend this method because it changes the elevation in the AP931250. Jabbgl decompiles the scenery bgl in order to change the elevation then compiles which in some cases can corrupt other important xml data for other airports in that same Region Letter/AP bgl.2. This is my first choice. Using the AFCAD program set runway, start location elevation to 130ft. It looks like the new plateau is somewhere close to that value. Forget about AI Planes that load when you start or go to SABA we only want to watch the AI Planes that are landing. When the AI Plane lands see where the wheels on the main gear are in respect to the runway. Tweak the AFCAD elevation up or down to get the main wheels set correctly on the runway when the AI plane lands.Once you have a perfect elevation with AFCAD for all the landing AI Planes now decompile the AP931250.bgl and copy out just the airport header like this.Change the alt="15.000F" to the precise altitude that you now have in the AFCAD. Ft to Ft or M to M your preference.add the compiler header and footer and compile with BGLCOMP.exe which looks like this<?xml version="1.0" encoding="ISO-8859-1"?> Now comes the magic of FS9. Place this new bgl using any name you prefer into the SceneryWorldscenery folder.This will force all AI Planes on start up of FS9 to load at the altitude specified in this header which should match the 3rd party airport elevation that sits up on the plateau.The exact same altitude in the AFCAD bgl is used for airborne AI Planes that are landing at SABA.There are a couple other tricks but are not as stable so I recommend you try number 2 and see if you can get it working for SABA.

[Guest jes-s]

>2. This is my first choice. Using the AFCAD program set>runway, start location elevation to 130ft. It looks like the>new plateau is somewhere close to that value. Forget about AI>Planes that load when you start or go to SABA we only want to>watch the AI Planes that are landing. When the AI Plane lands>see where the wheels on the main gear are in respect to the>runway. Tweak the AFCAD elevation up or down to get the main>wheels set correctly on the runway when the AI plane lands.This works perfectly, except that the runway is too short for the DHC-6. My solution was to increase the runway length in AFCAD (doesn't affect it visually). About 2100' works fine for the DHC-6. I also noted that landings only works for IFR flights. On VFR the airplane flyes to the mountain and crashes at about 1800'.>[...]>Now comes the magic of FS9. Place this new bgl using any name>you prefer into the SceneryWorldscenery folder.>>This will force all AI Planes on start up of FS9 to load at>the altitude specified in this header which should match the>3rd party airport elevation that sits up on the plateau.This also works perfectly.Now together with Saba I would also like to add AI traffic to St. Barths (TFFJ) with the st.barths_2004.zip and st-barth2.zip add-ons from AVSIM. Departures are no problem. The approach to rwy 10 is far from perfect, but acceptable. However, on the visual rwy 28 approach, the aircraft flyes through the terrain. If I want to fix this problem I assume that I need to add an approach to the airport file. I know a bit on how to add IFR approaches, but can I just modify how the visual approach is handled? (since I believe that TFFJ has no instrument approaches in real-world).

[jvile 1]

>I know a bit on how to add IFR approaches, >but can I just modify how the visual approach >is handled?That is the one thing we can't do at this time with the airport scenery both default or 3rd party.VFR visual approaches are hard coded to the airport scenery. Based on which direction the AI Plane is coming from it will fly a left/right downwind or left/right base or even a straight in hard coded approach. These instruction commands are called for once the User/AI Plane is within 85NM of the airport scenery or more precisely the reference LAT/LON data of the airport.FS9 does use a minimum elevation code for terrain clearence except when the VFR flight is cleared to descend to the Final approach altitude when entering the pattern. At this point if there is any high terrain the plane flys into it.The only work around is write a vectors to final offset curved approach with a altitude restriction in the XML which mimics a visual approach. The drawback is AI Planes must be on a IFR flightplan.You can manipulate the AI Plane behavior on a VFR FP if you tag the Flightplan with a TNG.Some small airports like SABA that sit on the plateau also have a larger hill on one side (backside of the ramp parking). The runway property data as seen with AFCAD owns the TNG tag in the FP. There are several codes seen with AFCAD that don't appear to do anything such as pattern altitude and right/left hand pattern. That is because these are the codes for VFR TNG. We can force a higher pattern altitude and right/left pattern for the VFR TNG if we change this area of the runway properties. One other worth while note is to give credit where credit is due.My no. 2 in the above post prefered choice that you used for fixing the elevation issues for SABA is the correct Microsoft FS9 elevation fix and not mine. This is what the SABA scenery designer should have done before releasing the scenery. It comes under the heading topic of changing the altitude of an airport in respect to a default coded exsisting flatten in the airport scenery.What you did was to preload FS with a basic AFCAD airport header with the new altitude data and then loaded it before the default airport altitude (APnnnnnnn.bgl) by placing the header into the worldscenery folder. We then used a second airport header in the AFCAD (at the higher addon scenery layer) to lay out the 3rd party airport scenery for (touchdown rollout) airborne traffic landing altitudes. They go on to say, To remove existing flattens, you currently have to edit the default code. A big no-no. I take that to mean any default code in the scenery folders. They also gave us the ability to write our own code and then if placed correctly (as per the SDK) it nullifies the exsisting default code and uses our new code. JABBgl edits default code in a default bgl and should never be distributed on web sites. It is your choice on how to fix the 3rd party elevation problems but in certain cases that may not be the correct way. I will continue to honor the way Microsoft wants it done.