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Holger

'Beta testing' of my AI manual

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Hi everyone:I'm just about done with a project that adds AFCAD files and flight plans to more than 40 small airfields in southern and central British Columbia. Nothing too exciting about that ;-) However, my package will include files and documentation to add a number of freeware GA aircraft to your AI system, including the Pitts S-1S, DHC-2 Beaver and Turbo Beaver, all of which needed to have their .air and aircraft.cfg files tweaked in order to "behave" as AI. Even if you're not interested in BC, you might be interested in adding those add-ons to your AITRAFFIC.BGL file.In the accompanying "manual", I wanted to share what I have learned about AI behavior and how to make those little buggers survive in mountainous areas. Below, I have pasted a few sections of my draft version and would like to have feedback from anyone interested on (1) how clear it is, (2) amount of BS, and (3) missing things. Some of the text might be tricky to fully understand without the rest of the documentation but I thought I give this unconventional approach to beta testing a go ;-)Any feedback is highly appreciated. Cheers, Holger----------------------------------------------------------------Known Issues:As many of you probably know, steep terrain and AI traffic don't work well together in Flight Simulator. Aircraft frequently dive into mountains (which they generally survive---providing some funky visuals when tracking aircraft with the aiview.dll module) only to crash on exit, particularly if they are in "landing" mode. If they don't battle with mountains, aircraft still might miss airports repeatedly, particularly those with short runways, and will disappear after three unsuccessful attempts. On other occasions, too high an initial approach often ends in a locked heading and altitude, with the AI aircraft continuing in a straight line, never to return.Once you've installed these set of files as suggested and start flying in between the AI aircraft, expect some of them to exhibit the following problems or unrealistic behavior:1. Aircraft disappearing into mountains or emerging from them---or not...2. Repeated overflight of airfields and disappearing aircraft (after three unsuccessful attempts).3. The odd "aimless" aircraft flying a straight line at low altitude.4. Some airfields, such as Castlegar or Lytton, have particular problems in getting aircraft safely on the ground.5. The four previous problems collectively lead to a slowly diminishing number of AI aircraft in each loop. Since FS2002 does not respawn crashed aircraft (actually, I have seen that happen occasionally but it is unpredictable), you'll have to reload a flight every few hours to regain company.6. Smaller airfields are prone to having aircraft taxi in opposite directions and thus either pass through one another or get stuck in front of each other. My AFCAD designs try to minimize the potential for this but some places just can't be made AI-proof within the limits of the airport visual scenery.7. For your own approaches to or take-off from some of the airfields, you'll notice that the tower will assign the same runway no matter which direction the wind is blowing. I closed off runway directions at these airports to force AI aircraft into a pattern with a higher likelihood of "survival". If you don't like this, load up the airport in AFCAD and remove the "close for..." checkmarks associated with the given runway.Despite these problems, I am amazed at how well the AI aircraft manage to hop across and in between the mountains and make successful flight maneuvers at small airfields. It's great fun to watch them zip around! Compliments to the aircraft programmers!----------------------------------------------------------------Technical Details:Given the issues mentioned above it's no wonder that the FS programmers left most airports in mountainous areas "undeveloped" and unserviced by AI aircraft. I decided to take on the challenge and ventured to design some flight plans with an acceptable survival rate for my home region---the mountain ranges and high plateaus of southern and central British Columbia. This section provides some info on what I came up with.Generally, a flight plan designer has four options available to influence the behavior of AI aircraft and their flight plans: aircraft type, flight mode (IFR vs. VFR), flight level (cruise altitude), and airport location/runway designation.1. Since different aircraft models behave quite differently when in AI mode, the choice of aircraft makes a big difference. Generally, the default FS aircraft (in any available repaint) behave well and look good too. Add-on aircraft are a mixed bag and often require testing and tweaking to make them function well consistently (the crucial test is watching them land!). Of the eight freeware add-on small aircraft I use with my BC flight plans, only the Piper Malibu Meridian, the Beech B33 Debonair, and the Found BushHawk-XP fly perfectly as is. For the other five, I had to replace the .air files with more stable ones and change data fields in the aircraft.cfg files. 2. Each flightplan (though unfortunately not each leg!) provides the choice of IFR or VFR mode. Most default and add-on general aviation plans use VFR mode but almost all of my plans are set to IFR for the following reasons:(a) In VFR mode, the aircraft will fly in a straight line towards the designated airport and begin with the approach legs just a few miles out. The advantage is that VFR mode appears to have a better terrain-avoidance system than IFR mode that often-but not always-prevents the aircraft from flying through mountains. However, in steep terrain this feature interferes with the controlled descent and the aircraft almost always ends up way too high on first approach and on subsequent trials either never descends far enough or ends up flying through adjacent mountains anyway.(:( After an unsuccessful attempt at landing in VFR mode, the aircraft will pull up its landing gear, if applicable, and climb a few hundred feet but then immediately drop the gear to begin the next traffic pattern. Aircraft in landing mode are more vulnerable to terrain obstructions (I guess the contact points in the aircraft.cfg file become "active") and usually crash when maneuvering in the narrow valleys. In IFR mode, the legs of the re-approach are longer and the gear only drops down on short final, giving a much better chance of survival.3. For the small aircraft, I set the cruise altitude (flight level) for each leg of my flight plans about 2,000 ft above the highest mountaintop along the route. I didn't want to set higher levels because it's unrealistic (for unpressurized cabins), leads to frequent overflight at first approach, and doesn't seem to help much with avoiding mountain fly-through.4. Obviously, location and configuration of the airports in each flight plan influence the flight pattern of the AI aircraft. With the help of maps and extensive testing, I designed the legs of each plan to maximize the likelihood of a smooth and uninterrupted (by mountains) flight. In this final version, I ended up with six independent loops of seven airports each, which I populated with 14 different small aircraft. Each airport has two aircraft staying overnight; there are no night flights. Each morning sometime between 9 and 10AM local time the "dance" begins: following a staggered schedule, all aircraft fly in the same direction to and from the seven airports within each loop. -----------------------------

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