Drive through parking

Interesting tutorial, I was peripherally involved in very early development of the plumbing system (a term coined by Matthew Ministry back in the days when PAI was dominant - maybe 2002/3?) MM discussed the subject with Norman Dean (who does the UK2000 payward afcads) and I helped him test an AFCAD for ISD's Milan Linate, where most of the stands are drive-thru.

The plumbing idea was not MM's invention though (he just coined the term), since someone had already created an Afcad for Linate that used this system, MM wanted to make a version that didn't have kinked taxiway routes (to lengthen the route into the spot) and discovered that connecting the outbound tracks to the furthest entrypoint to a runway was the key to making it work particularly reliably.

With regard to the tutorial, you mention that AI uses black links in the shortest route to the threshold, but that's not universally true. At Linate there's a GA area on the opposite side of the main runway (there are 2 parallel - one of which is very short and MM sized it for single-engine GA arrivals & departures). When a/c are departing to the north, GA aircraft that use the main runway (eg bizjets) will cross the main runway and use the taxiway on the far side from their parking spot in order to reach the threshold. If they used black links with impunity they would take the runway as the shortest route. There are 2 possible reasons for this, 1/ The black links are on the active runway and are "out of bounds" or 2/ Aircraft have to arrive at the hold-short for departure from the non-runway side - that is, facing the runway. In my experience AI has an aversion to using black links but use them if there is no other workable option (AI will also use taxiway sections marked as closed if they have to).

Also I'm not sure my experience agrees with your assertion that arriving AI are allocated a parking place prior to reaching a hold-short node after exiting the runway. In some layouts I've developed (including MM's Linate one that I helped to test) aircraft would stack together in a gate for no apparent reason (we'd end up with 6 airliners merged together in one parking spot). What was happening was that these aircraft were not encountering any hold-short nodes (one had been omitted in the complexity of the plumbing taxiway system). This meant that the arriving a/c would go to the last parking spot that had been allocated to an a/c that had hit a hold-short node (by taking a different runway exit that was properly constructed). I take this as evidence that parking spots are allocated only when an arrival hits a hold-short node after exiting the runway (because when they do, they go to a different parking spot and don't stack together).

The AI system (even for FS9) is still a black-box kind of problem where experimentation is all we have in the absence of any real information. For example, AI arrivals will sometimes use runways marked as closed for landing even when there's a parallel runway available, eg Heathrow, where I use the southern runway for departures only, but have seen a BA 767 arrive on it all the same even though it is closed for arrivals at both ends.
 
AI arrivals will sometimes use runways marked as closed for landing even when there's a parallel runway available, eg Heathrow, where I use the southern runway for departures only, but have seen a BA 767 arrive on it all the same even though it is closed for arrivals at both ends.[/QUOTE]

I had a simmilar problem with a stock airport that I added some parking spots to, Can't remember which one but it had two parallel runways, One tarmac Open for takeoffs and landings and one a short grass Closed for takeoff and landings and I had heavies landing on the grass strip until I increased the length of the tamac runway just a bit then all worked well even after opening the grass runnway.

Regards Frank
 
The AI system (even for FS9) is still a black-box kind of problem where experimentation is all we have in the absence of any real information. For example, AI arrivals will sometimes use runways marked as closed for landing even when there's a parallel runway available, eg Heathrow, where I use the southern runway for departures only, but have seen a BA 767 arrive on it all the same even though it is closed for arrivals at both ends.
You cannot close a runway completely in FS9 or FSX. What you can do is lower the runway score card so another runway is prefered. AFCAD was not designed to lower the scoring of a runway in FS9. The closing checkmarks are a holdover from FS2002 where a one end of a runway could be closed.

All this changed when FS9 was released. In order to lower the runway score you have to remove all associated approach code for that runway. AFCAD or any airport utility that mimics AFCAD cannot do that.

FS will never leave a IFR FP airplane in the sky. They always must land. It does not matter if the only runway available is 1000 ft long with no approach code a B747 on a IFR FP in zero visibility will land on that short runway.

Also I'm not sure my experience agrees with your assertion that arriving AI are allocated a parking place prior to reaching a hold-short node after exiting the runway.
The parking spot is allocated when the AI Plane reaches the taxi in segment of the flight. There are 4 segments to an arrival AI Plane.

Enroute
Landing
Rollout
Taxi In

Taxi In occurs when the AI Plane slows to 20 kt IAS while on the runway. At this point the parking spot is assigned. It has nothing to do with the holdshort node. The arrival holdshort node has one purpose and that is for switching to ground freq. If no hold short exist then planes stack up at the parking spot based on the sort list of parking that FS uses.

With regard to the tutorial, you mention that AI uses black links in the shortest route to the threshold, but that's not universally true.
I agree. Only the first plane in the takeoff and landing sort list will normally use the shortest route. When a airport fills with takeoff and landings ATC does its best to avoid taxi stalls between airplanes. You will see AI planes exit runways in opposite directions and take longer taxiway routes to avoid other AI Planes that are taxing out to a runway. It is for the reason the plumbing system does not work for all airports.

The plumbing system is trial and error. There is no such thing as a oneway taxiway in FS. It might appear that AI Planes taxi on a oneway link but when airports get conjested (on the ground) AI Planes will taxi across grass to bridge a taxiway link. At that point it does not matter which way the taxiway is set for the parking spot.

The plumbing system must be tailored for each individual airport and that is not a guarantee that it will work correctly. The Flightplans for my AI Planes may be from one developer and yours may be from someone else. That also plays a part on what your plumbed airport may do vs your airport using my FP's.

I have downloaded developers airports that use the plumbing system. In their testing it worked. Once my Flightplans were used for that same airport the plumbing system falls apart. The end result is each user must tweak the plumbing based on how their airport is used. The larger the airport the less likely the plumbing system will work. Try plumbing KORD or EHAM with all runways active. Major caios.

In FS9 the turnout parking works well
In FSX the pushback parking limit works well.
 
The parking spot is allocated when the AI Plane reaches the taxi in segment of the flight. There are 4 segments to an arrival AI Plane.

Enroute
Landing
Rollout
Taxi In

Taxi In occurs when the AI Plane slows to 20 kt IAS while on the runway. At this point the parking spot is assigned.

The arrival holdshort node has one purpose and that is for switching to ground freq. If no hold short exist then planes stack up at the parking spot based on the sort list of parking that FS uses.
Old thread, I know, but I was looking for something else and stumbled on this reply.

Basically, then, the failure of an aircraft to go to the correct parking spot allocated while it was on the runway, is because it didn't switch to the ground frequency and was never verbally told what spot to use? I can't see why FS wouldn't just take the AI to the gate it earmarked regardless of whether it contacted ground or not (knowing that to do otherwise would be to stack aircraft in a parking spot). Evidently a coding glitch, there.
 
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