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Question for an AI guru...

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Guest Stan V

First, please understand that I am a complete novice with respect to AI. I have it, I have TTools, and AFCAD etc. but I've never done much with them. I recently downloaded an airport scenery file and when I went to the airport in question, four AI aircraft immediately queued up for takeoff. As I understand the TTools documentation, this happens because all of the aircraft scheduled to leave in the 5 minutes prior to my arrival immediately depart. So far, so good. However, the departing aircraft at the head of the line waits for awhile at the Hold Short line and then poof, disappears. Everybody moves up one position and then it happens again and again until the queued line is gone. Each aircraft doesn't takeoff, it simply vanishes after waiting a short time. Why is that? Again, TTools docs say that aircraft that are prevented from taxiing for 5 minutes will disappear but I can't see anything preventing the lead airplane from leaving. I did check my TTools data for the airport in question, however, and there are no aircraft resembling the aircraft queued up for takeoff listed in the AI files for that airport. Could that be the root cause of this behavior?Can anybody offer any insight here?Stan V.

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Stan, One question to ask is, did the scenery come with a new AFCAD for the airport? If it did, you might want to check it and make sure that the hold short points are in the correct spot. I had a simular problem with one and after checking it, it had no hold short point for the runway, which I guess caused the planes to wait and then disapear. This was some time ago, so I can not remember if the planes held short of the runway or if they taxied onto the runway and then just sat there. But I do think that the problem is most likly the AFCAD and not the flight plans. Also I noticed that sometimes using the fualt finder in the program does not always find a problem, so make sure you check everything. Anyway good luck I hope this helps.Glenn

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Guest Stan V

Glenn,Your explanation sure fit the observed symptoms - and thank you for responding. However, I checked the AFCAD file that came with the scenery (yes, there was one and it is the only AFCAD file for that airport on my system) and the AFCAD program found no problem with the Hold Short line at the intersection where I observed the problem. I guess the book is still open on a cause. Any other ideas?Stan V.

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Stan, I thought of something else. Are the planes all the same type? The reason I ask is that when I was using fs 2002 I had an airbus 320 that would do the same thing at toronto. All of my other planes would takeoff just fine but when it was there turn it would just sit there, until it disapeared. Then the planes would takeoff again like normal until one of those planes showed up again and the same thing would happen. Do your planes even call for takeoff clearance? I know that mine did not. So I changed the air file and it seemed to work. I do not know what one has to do with the other. I am no expert with any of these files, but I have been doing my own AI since fs 2002. One other thing to check in the AFCAD file would be that the hold short point is conected to the runway. Hope you figure it out, I know it can be very frustrating working with all these files but very rewarding when it all works right.Glenn

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The reason why a AI Plane will dissappear after 5 minutes sitting at the holdshort node is because it never contacts the Tower for takeoff instructions.What causes this is the holdshort node distance is not set right. AFCAD docs say"The program can display 225 foot radius circles around all the hold-short nodes to show the maximum allowable distance."This is nice to know but what we must understand is the Overrun area of a runway is not seen in FS9 as part of the runway. Only the actual runway and a Displaced Threshold is seen as a complete runway.If the runway end has a Overrun area that the taxilink connects to make sure the 225 ft radius touches the actual part of the runway and not just the Overrun area. If the radius circle does not touch the runway the AI Plane will disappear after 5 minutes.

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Guest Stan V

I hear what you all are saying but I've checked the Hold Short distance from the edge of the runway and it is well within the AI limit. That's not the problem. Here is a more complete description of the situation: The taxiway intersects the runway about a fifth of the way down its length. There is no runway start location in the AFCAD file at the place where the taxiway and runway intersect. There is, however, a start location at the nearest end of the runway, some distance away. My impression is that after receiving clearance at the hold short line, an AI aircraft should turn onto the runway and taxi along it to the end where it would turn around 180 degrees to takeoff. For some reason this is not happening. The hold short line is as far as each aircraft goes. This happens with every aircraft and I have observed it happening with several different types of a/c so I would suspect the problem is not being caused by an aircraft model. I checked the links on the runway itself between the hold short node and the start location and they were of the "runway" type, not the "taxiway" type. Should they be the taxiway type? Is that the problem? Also, there is turnaround pavement at the end of the runway adjacent to the start location. Should there be corresponding taxiway links there to guide aircraft around the turn? Currently, there are no such links.Stan V.

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Stan, The links on the runway need to be the black runway taxi links, but you need normal taxi links from the hold short node to the normal node on the runway. Also in fs2004 the AI planes will make the turn at the end of the runway and recenter themselves, so you don't need that either. I seems as though everything is how it is supposed to be. Being that this is a modified AFCAD you could go look at the original one for that airport to see how it was set up, just to see if you can see any diffences. Hopefully someone with more experince will come along and give you the answer you are looking for. Sorry that I could not be of more help to you.Glenn

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Stan,Have you checked the AFCAD for faults (using the fault finder option in the tools menu)?Failing that, you may have to come clean and tell us the airport and runway so someone can actually have a look.Hope this helps,Ian

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Hi,A possibility - check to make sure the hold short node is red (not yellow). Only red ones will be accepted by FS as real (the yellow ones just create ILS hold lines).You can create a taxiway link around the turnaround point if you wish; this sometimes helps them in turning around.Hope this helps,--Tom GibsonCal Classic Propliner Page: http://www.calclassic.comFreeflight Design Shop: http://www.freeflightdesign.comDrop by! ___x_x_(")_x_x___

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Guest Stan V

I wasn't trying to be obtuse - I was merely trying to avoid pointing at the author unnecessarily. However, maybe if more folk looked at the file, we/I could solve it. I doubt the problem is unique - more likely it happens at a number of smaller airports that do not have separate taxiways parallel to each runway. The file in question is the AFCAD file contained within the Sudbury Ontario Canada scenery file. The file is cysb.zip and it is available here in the AVSIM library. The behavior I describe can be observed (on my system) by starting from RAMP 2 parking at about 11:30 am and observing the taxiway-runway intersection in the background when a Fairchild Metroliner departs. I hear the pilot ask for taxi clearance and a corresponding reply from ATC. However, I admit to be somewhat confused by his taxi clearance because it mentions Runway 4 yet the aircraft heads in the opposite direction toward the intersection I have been describing with Runway 12/30.This might be the problem... The Active Runway is Runway 22 which is at the opposite end of Runway 4. On this airport there are no taxiways parallel to 4/22 other than the one parallel to Runway 4 and the only practical route for taxiing to Runway 22 from parking would be to go from parking to the intersection with 12/30, from thence down Runway 30 to the intersection with 4/22 and from there out on 22 to the end followed by a final 180 deg turn. Thus, it appears that depending on the Active Runway, any one runway except runway 4 might have to be used for taxiing. I'm pretty sure that the AFCAD links along all of those runways are "Normal" links, not taxiway links. I will try changing their type and see if it solves the problem. What do you think?Stan V.

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Guest Stan V

My ideas above didn't work but in re-reading previous posts, I notice a distinction between "normal taxiway" links and "black "runway taxiway" links. How does one convert from a former to a latter one? When I double click on linktype in the AFCAD dialog box for a link, I get only choices of "Runway", "Taxiway". "Apron Route", and "Closed". They originally were "Runway" in the file and I changed them to "Taxiway" but, as I said, that didn't make the difference.Okay, another idea: When I got my taxi clearance for runway 22, I was told to go via taxiways beta and alpha. In the AFCAD file for this airport, the taxiways do not have designators although the capability is there in the dialog box to provide one. Can it be that simple?Stan V.

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Guest Stan V

Sorry - it wasn't that simple. The aircraft still vanish after a 5-minute wait time. I'll wait to see what the real experts (you all) come up with. Yes, I did check for faults (using AFCAD) and found none. The Hold Short nodes are regular Hold Short nodes, not ILS Hold Short Nodes. The AFCAD Help says that Runway taxiways should have runway designators and mine now do although that change didn't solve this problem.Stan V.

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Stan, Just me again. Thank you for letting us know the airport. I haven't got the scenery yet but I did look at the default airport. The default airport does exactly what you are saying. I set it up so that rwy 22 was the active and my AI cessna got to the hold point and sat there until it disapeared. The taxiway Bravo and Alfa are both there. (in the default file) Bravo runs to the end of the parking and then it becomes Alfa. So it is the same taxiway with two different designaters. So my AI was supposed to go B A rwy 12 rwy 4, then turn 180 and takeoff rwy 22, but it doesn't. So I requested takeoff and was sent the same way. I got to the hold point to rwy 12 and tuned the tower. But I had no options to request takeoff. So I taxied out rwy 12 and it wasn't until I got near rwy 4/22 that I got the options to request takeoff. So that is the problem. I just do not know how to fix it, except making rwy 12/30 a normal taxiway. But there has to be a fix to this problem. But at least now we know why they are not getting the clearance. I hope everyone can follow my rambling. I will deffentaly look into this some more because know I am getting curious about the whole problem.Glenn

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tried to edit my post but couldn't. I have been trying different things. But so far the best solution I can come up with is to add a taxiway from taxiway Alfa to runway 4/22 that is parallel to rwy 12/30 and make it taxiway C. I put a hold short node near rwy 4 and ran a taxiway up to the last blue node before the hold short that has been giving us the problem. I am sure that there is a better way to get this to work I just haven't found it yet. Also I noticed that when the planes go to make there turn on rwy 22 they turn to the right not the left, so to use the extension for the turns you would have to add some nodes and taxiways to turn them. They line up with the center line without it but they go through the grass. That is it for now, I just hope someone out there has a better solution to this problem.Glenn

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