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What is the 'logic' for arriving AI aircraft

jparnold

jparnold

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australia
Hello

I know that if any other aircraft (AI or not) is on a runway then any arriving AI aircraft will not land on that runway and will do a 'go around'.

Is there any other reasons an arriving AI aircraft will 'abort' a landing and 'go around'?

I have just added parking and taxiway taxi paths to my airport which are on the other 'side' of my runway from the existing parking and taxiway taxi paths. I also have set up the parking and ai aircraft so that only some of my ai aircraft can park on one side and other ai aircraft can park on the other side.
Note image below from ADE - the black line is the runway and the blue lines are taxiway taxi lines and green lines are taxiway paths (the reason for this is to create 'drive through' parking spots which don't have pushback).

taxipaths.jpg

I noted this 'behaviour' -
When only one of either ai aircraft 'type' arrives it taxis to the correct side parking of the runway and to its parking area.

If one ai aircraft has already actually landed and is on the taxiway to its allocated parking (NOT on the runway) and another ai aircraft arrives for the 'other side' it aborts landing and does a go around and only twice and then disappears.

Is there something I have missed or should I post this in another forum?

Thanks
 
Thanks Guenther,
I have hold short points on the taxipath paths ONLY as these are the ones used by ai aircraft when departing (I am using drive through parking). I didn't think that the taxipath taxi (used by ai aicraft which have arrived to taxi to their parking) would require them as they are only used by arriving ai aircraft and I had noticed that before I added the extra taxipath taxi on the other side of the runway that ai aircraft would still land even if earlier arriving ai aircraft had left the runway and were on the other taxipath taxi on their way to their parking.
According to the manual for Airport Design Editor "ATC also uses these taxiway points as checkpoints for takeoff clearance" and there is no mention of clearance for landing/taxi for them.

I will add them to see what happens.

Are there any other reasons (other than aircraft on the runway) why arriving ai aircraft abort their landing?
 
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There is no experimentation necessary to know that hold short nodes are required by the simulator at all entrance paths to the runway for proper AI functionality. The section quoted in the manual is not intended to define functionality and judging by the wording, it is likely that Helli is unaware of this requirement. However, he certainly covers it here with this statement:
Hold-Short taxiway points create visible hold-short bars on the link. ATC also uses these taxiway points as checkpoints for takeoff clearance. If hold short taxiway points are too far from the runway it can cause AI aircraft to freeze at the runway. See Hold-Short Limits below.
Click to expand...
It should go without saying that a nonexistent hold short is too far and it should also go without saying that the equivalent to freezing at the runway for arriving traffic is an aborted landing.
Suggest you thoroughly apprise yourself of section 5.1.5 Hold-Short Taxiway Point Limits.
 
Thanks Rick,
I note what you state and it makes sense, however in my case it I am not experiencing problems with 'takeoff' which those references are about. My 'problem' is with ARRIVING aircraft.
The documents states "That will result in ATC never giving you takeoff clearance and AI aircraft will stop at the hold-short taxiway point and get stuck there."
What appears to be a problem I am experiencing is that although there is NO arriving aircraft on the runway (there is one already landed and taxiing to parking) the next arriving aircraft aborts as if there is still an aircraft on the runway.

Anyway I just did another test and the problem experienced before (which resulted in my thread) did not happen. I have no idea why it did before and that is why I asked what is the 'logic' (or behaviour) of ai (landing) aircraft. I wondered could perhaps another vehicle on the runway cause a landing ai aircraft to abort. Is there a document which describes what to expect with ai aircarft?
 
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As the landing aircraft is not passed from "Tower" to "Ground" ATC "thinks" it is on the runway...
:)
 
I forgot to mention that I have added hold short points on the 'arriving' taxipaths as suggested even though I considered that there were only used by ATC to hold DEPARTING aircraft from accessing a runway already in use. Maybe that fixed my initial problem.
 
Your assumption based on the ADE manual is incorrect. Hold short nodes are critical for ATC to know that a plane has arrived *and is clear of the runway*. As Guenther, says, ATC will *not* think the plane is clear of the runway until it crosses a hold short node.

Another thing a hold short node does is to increment ATC to the next parking spot. If not there, the plane will park on top of the plane that arrived previously.
 
Thanks again Guenther,
The ADE manual then doesn't explain all the uses of hold short points? I had nothing else to 'work' on and hence my question about other documentaion on AI aircraft behaviour.
What was confusing to me was that I am using 'drive through parking' and therefore taxiway paths and taxiway taxi links are used for different things and as the ADE documentation only mentioned hold short points relative to depaarting aircraft I didn't see the necessity to have them for arriving aircraft, AND my thread is titled 'logic for ARRIVING aircraft'
I have learnt something new and perhaps other readers have too.
 
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AFAIK there is no such reference that describes the complete uses of hold short nodes. Thus please don't think I was "blaming you" for not knowing this - I wasn't. Sorry if you got that impression.
 
Thanks Tom. I thought that perhaps there was something in SDK I had missed.

I guess if I had thought about it enough I might have considered that ATC might use the hold short points in both directions and that arriving aircraft may be considered as still being on the runway even though on the taxiway if an arriving aircraft has not passed a holding point - well that's what you and Guenther have pointed out and thanks again.

My 'stumbling block' I guess was that I am using separate taxi ways to and from the runway to allow for drive through parking.

It's all working very nicely now thanks and it's nice to see some aircraft exit left and some exit right.
The only thing which kind of annoys me now is that one of my aircraft touches down much closer to the threshold and pull up much faster than the other one even though it is a turbo prop and therefore would 'fly' faster (they are both single prop and much the same size). I have read threads about this and know that certain parameters in the aircraft.cfg affect this but I can't be bothered trying to adjust them - it's just a visual 'thing'.

Thanks again.
 
Hi John, You mention in this rather old thread, that you use drive through parking. Can you explain how you get this to work, as it really bothers me to see ai at parking spots, where they in real life would drive through instead of making the arkward push back and sometimes doing a 180 turn to get to the taxi path.

Jorn L
 
Hello Jorn,
It's been some time since I created an airport with drive through parking but I will do my best in describing how to achieve this.
Firstly you need TWO taxipaths, one coming from the runways and one returning to the runways and I am not sure if you have to but I used TAXIPATH type TAXI for the taxiways FROM the runways TO the parking gate and TAXIPATH type PATH for taxiways FROM the parking gate TO the runways.
Also I made sure that the TAXIPATH type PARKING is kept as short as possible otherwise your AI aircraft will be seen to do a short 'pushback' when departing. Obviously this is up to you if you don't mind if the AI aircraft does a small pushback or not.
I used an excellent document to understand all this named “DRIVE_THROUGH” PARKING and OTHER AI AIRCRAFT CONSIDERATIONS" and written by Don Grovestine in 2008 where Don describes drive through parking using the "plumbing method". You can get it at http://stuff4fs.com/Tutorials/Drive-Through Parking Tutorial.pdf
There is another tutorial at https://www.avsim.com/blogs/entry/45-the-challenges-of-drive-through-parking-implementation/
It took me quite some time to get the 'hang of it' (probably because I am now retired and not as 'quick' as I used to be) but once I got it working I was very happy.
Consider the following two images from ADE of an airport with drive through parking. Sure it is of a water airport but the principal is the same except you would create your taxipaths on existing taxi ways and aprons as the AI aircraft will faithfully follow the taxipaths regardless of if they are over buildings or whatever. Note take no notice of the direction of the arrows on the taxipaths - they do not effact the direction of AI aircraft. If you are doing this for an airport you have created from scratch then this will be easy to do as it will have your aprons and taxipaths already 'drawn'.


drivethrough2.jpg


drivethrough1.jpg

Hope this helps
John
 
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Sorry for the late reply, but real life got in the way :-)
I've taken a look at your ADE and looked in the tutorials you're referring to, but I must admit (and I'm also retired), that I still don't get it. I don't know if you own FlyTampas' Corfu, but I use it a lot and they have the drive through parking, If you use it, could you maybe show me the ADE for that, where you have "fixed" it, as I think I'll better have an idea of it, if it's an airport I know and recognize. If you don't have it, Ill see if I can figure it out from your explanation. I might have to read it a few times as English is not my native language, but I hope I'll get there in the end. :-)

Regards Jorn
 
Jorn
Have a look at the attached airport file from ADE loading the Corfu airport. The ramps (parking at the top and bottom) have drive through, the others don't (will require pushback). The FSX AI 'engine' will not direct aircraft with a wingspan under 32.0 meters to these as the parking has a restriction of 32 meters or larger.
corfu.jpg

Apart from that have a look here -
https://www.fsdeveloper.com/forum/t...th-what-is-the-difference.439386/#post-764805
Also
https://www.fsdeveloper.com/forum/threads/plumbing-method-help.437287/#post-743643

Also search the Airport Design Editor forum for threads containing the words "plumbing" and "drive through parking). I looks complicated but I can assure you that it isn't.
John
 
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I have tried making blue paths from rw to parking and green taxi to the rw on three parking spots. I want them to "drive" something like the red path I've drawn to show you what I want to acieve. Does it look right or what else do I need to change?

Jorn
 

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Jorn,

It looks ok but you need to test it to make sure by creating some AI traffic. Are you creating a new airport which didn't exist before? If so then send an image of your airport from ADE so I can check.
 
It's the ADE from FlyTampas Corfu LGKR I have tried with. I have only changed the bottom three P-spots so I don't mess it all up (don't worry, I have taken a backup of it first), but I just wanted you to check it before I compile it. And yes, I have plenty of ai in / out of Corfu, so I'll give it a try and compile it, and see if it makes any difference.
 
Jorn
I am not sure exactly what you are trying to achieve. You say that you have plenty of AI in/out so what are you trying to achieve OR is it that you are using CORFU as a 'template' to understand how you create a new airport? Yes those 'red' lines look ok.
Looking at FlyTampas Corfu it already has taxipaths set up for drive through parking at those ramps and so with airport traffic settings set correctly you should occasionally see AI aircraft taxi to those ramps and then depart in the same direction
BUT HEY I just noticed something which may be a problem and cause NOT many AI aircraft going to those ramps and that is (looking at the properties by right clicking on the ramp in ADE) the 'type' is RAMP_MIL_CARGO and if my memory serves me correctly (long time since I did this) ONLY AI aircraft which have atc_parking_type (this is in the aircraft.cfg file for each aircraft) set to RAMP_MIL_CARGO or CARGO will ever be directed to those ramps.

You see AI aircraft will only be directed to ramps which an atc_parking_type which 'matches' the aircraft and also which have a wingspan NOT GREATER than TWICE what RADIUS in the properties (wingspan is twice radius) and there also is AIRLINES which need to match (also in properties and in the aircraft.cfg file BUT that that is set to 135_airways for these rampw which should be an issue.

They are properties you can play with for various outcomes like preventing certain aircraft from ever being directed to a particular ramp.
So going over those properties again
RAMP type
RAMP radius
RAMP airlines
 
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