Why would AI A/C not leave preflight?

Hey guys,

I'm having trouble with an airport i've been working on. I've taken an airport that was previously modified by another member that activates crosswind runways. All of that works fine.

I've tweaked and changed around with it a bit using FSX Planner though and found that a lot of aircraft, from specific gates never leave their gate. Opening traffic tool box explorer I can watch their departure time approach and pass, and watch as they enter 'preflight' stage, but the baggage cards never come around, nor do they ever push back. The fuel truck DOES come around, so I know its not a matter of too few vehicles.

I can't establish a common thread between the gates that arn't working. Reading another post I just thought maybe it could be because perhaps the taxiways don't have a name (or letter). Could this be it? I'm not at my pooter to check. Or does anybody else have any other ideas or encountered this problem?



Resource contributor
Don't think its the un-named taxiways. I have several airports with unnamed taxiways.

Is the traffic using IFR or VFR flightplans?
You could have a taxiway link line open. Even though a node may appear attached it may not be.

I would look for a open Taxiway link line that is common to the AI Planes that will not pushback. Trace all parking spot lines that are effected backwards until you see the one that is common to all. This may be where the break is occuring.
Try also to see if the actual parking spot has set the value on the Push-Back property to either Left, Right or Both.

I had that problem, so after changing it to Both, my AI nicely pushed back and continued out to the RWY and took off...

(Well actually, the first time it only wet to the takeoff1-stage, and thus never took off, because I missed a holding point before entering the RWY, but that's another story ;-))
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Resource contributor
I know this is slightly off-topic, but still: I had a nice scenery in FS9, somehow I even managed to make traffic fly a proper circling approach via a quite demanding path: after end of a VOR/DME approach that was offset by 26 degrees to the runway heading, traffic entered right hand downwind for the opposite runway(if wind conditions were dictating use of the opposite runway that has no IFR approaches at all), flew the pattern and landed as any decently behaving traffic would; but that was in FS9. I adopted the visual part of scenery for FSX, converted the AFCAD to FSX standard, got all the stuff with fuel, pushback, traffic is departing without a glitch, flies approaches, that are offset to the primary runway, but if I change wind direction to force use of the opposite runway, traffic starts approach, calls the tower, gets the clearance and doesn't reply to that. After a couple of calls from the tower, the plan is cancelled and traffic flies the last track of the VOR/DME approach, overflies the fix and continues straight ahead on the final leg of the final leg and into the mountain, traffic explorer is stating "rollout". I tried numerous tweaks of approach legs, but none works, so it's obvious in FS X something changed that prevents AI traffic to fly circling approaches. I simply can't find that "something". Any ideas anybody?

I have also identified the same problem where Parked planes cannot get out of Preflight Support mode (preclearence).

So far the problem is with some of the German airports such as EDDF and EDDM.

This does not appear to be a FSXP or ADE problem but a FSX airport problem. I am testing stock airports and EDDM has one whole row of 14 Gates that will accept arrivals but AI Planes that spawn on startup go into Preflight mode and get stuck.

I had to move all the planes to the other Terminal before they would Call Clearence at both EDDF and EDDM.

I am still testing to find a cause but the problem is leaning toward a Clearence Freq issue (amoung others) when Panes will not come out of Preflight mode.

The NONE, LEFT, RIGHT, BOTH pushback are holdovers from FS2002 that FS9/FSX does not use. We tested this element tag over the last 4 years and none of the options have any effect on pushback vs no pushback.


The circle Approaches coded into FSX are still working the same as before. None of the approach code behavior was changed in FSX and I have already written several Approaches in my uploads that use LDA, OFFSET ILS's, Multiple runway usage, etc.

What has changed is the way FSX flips the runways (winds) when either the airport is VMC or IMC which can have an effect on IFR/VFR flights. If a airport becomes IMC and there is no IFR approach (based on winds) FSX also reverts to a hard code dll approach so the planes will still land. Some airports don't always work as expected so testing is required.

FS9/FSX PAUN in Alaska has circling approaches coded.


Resource contributor
Jim, thank you for your prompt reply, however, I can't agree with your statement that circling approaches in FS X work as they worked in FS9, since for FS9, I had a nicely working traffic situation and the same setup simply doesn't work in FS X. YOu can give it a try yourself, both files are available here, this is FS X version:http://library.avsim.net/download.php?DLID=97518

and FS9 version is herehttp://library.avsim.net/download.php?DLID=65986

set visibility at 2 miles and wind from 150 degrees and you'll see traffic performing VOR/DME 34 approach and after MAP entering downwind for 16, while in FS X that won't happen. I also checked a nearby default airport that has a straight in ILS approach and under IFR and winds dictating circling to land to opposite rinway, exactlly the same thing happens - AI traffic goes beserk in FS X, while in FS9 it lands as expected.
YOu can give it a try yourself, both files are available here,
With all due respect, I don't think I will do that. Your problems have nothing to do with FS and everything to do with tampering, rewriting, coping and distributing Microsoft Copyrighted bgl files in both FS9 and now FSX.

A big NO-NO as per public statements that MS/ACES has made in the past 6 months.

I would strongly suggest you read the SDK's so you stop corrupting the root files that FS works with and passes to the dll's for many airports in one single bgl. Learn what deleteALL= means in FS.

Put back the MS stock AP9 (your FS9), APX (your FSX) bgl files then have AI go fly that nearby airport again. Just might work the way FS entended it to.
The NONE, LEFT, RIGHT, BOTH pushback are holdovers from FS2002 that FS9/FSX does not use. We tested this element tag over the last 4 years and none of the options have any effect on pushback vs no pushback.
Well whether FSX uses it or not, it is the only thing that makes my AI leave preflight and continue.... I've have tried it several times now....

AI goes in preflight, and if the parking-spot has NONE in the PushBack parameter it just vanishes, put in LEFT, RIGHT or BOTH, and all is bliss...that is the ONLY difference whether the AI-aircraft continues or not....

So I beg to differ that FSX doesn't use this parameter...
Well whether FSX uses it or not, it is the only thing that makes my AI leave preflight and continue.... I've have tried it several times now....

AI goes in preflight, and if the parking-spot has NONE in the PushBack parameter it just vanishes, put in LEFT, RIGHT or BOTH, and all is bliss...that is the ONLY difference whether the AI-aircraft continues or not....
Now THAT is very interesting...

I have not experienced AI holding up on preflight but I will keep it in mind if I ever see it.

Really interesting that it's happening at stock EDDF or wherever was mentioned in Germany. Maybe the afxxxxx.bgl file for those German airports has Pushback "NONE" at those parking spots?
Just looked into EDDM- Default:

As a matter of fact:
RAMP_GA_MEDIUM1-4 and RAMP_GA_SMALL 5-7 has NONE as parameter

The rest of them has BOTH (just took a quick glimpse)

So if you where watching any of them Jim, that might be the issue....

Same goes for EDDF (mostly on the RAMP's) Too many to list here....
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Hey guys, appreciate the replies,

I've done some more troubleshooting. I can't seem to find a common theme like the pushback method. All my gates have pushback set to both, so I don't think thats the issue here, also, the AI aircraft don't just disappear like they tend to do after 5 minutes of waiting and nothing happen. I've had them sit in their gate for up to 90 minutes after the departure time.

Strange thing is that I've tried the same airport a number of times, and sometimes AI will get stuck in certain gates, other times it won't. There doesn't appear to be a common thread. I can't figure it out.

What I find strange is that the ground vehicles just don't come out to the aircraft, yet it enters preflight..

Jim did you have any ideas about this clearence issue you talked about?

Is it your own AI-flightplan, and is it a default aircraft or a third-party?

And could you send or show the XML?

I'm using Ultimate Traffic flightplans and a mix of AIA and EvolveAI aircraft. It doesn't seem specific to aircraft as I've witnessed it with various types. I'm begining to think its an internal problem with FSX rather than the airport itself as sometimes I'll load up the airport and A/C will operate fine, then ten minutes later I'll load up the same airport, look at the same gate and the A/C will get stuck.

10 minutes later, is that FSX-time or real time, if it is FSX time it might be a different aircraft at the same gate..... so could be the aircraft as well....?

I could also be the famous 15 minutes that AI has to "settle in" before it acts "normal"....

Strange things has happen before when jumping in to watch AI right from the start..... 90 degree dives, flying under ground etc. etc.... when AI is "caught" in the middle of a flightplan a completely different place than it thought it should be, It behaves rather radically.....

I'm just trying to throw ideas up in the air here.....

I have narrowed the problem down to the animated Preflight Support ground equipment.

Turn off (slider full left) all Airport ground Traffic and then you should see the AI plane get passed Preflight Support and call for clearence.

When you start FSX and go to a airport all AI Planes sitting at the Gates are in Sleep State. When the Time reaches compiled Flight time the AI Planes come out of Sleep State and goes to FLT PLAN State.

FLT PLAN state reads the FP and then the AI Plane goes to PREFLIGHT SUPPORT state. In this state the Conveyor must move to the baggage door followed by the baggage cart. Also during this period the Fuel truck is called for.

When the PREFLIGHT SUPPORT state is timing out the Ground equipment return to park and the AI Plane goes to CLEARENCE State. Now comes PUSHBACK1 which calls for the pushback tug. When the pushback tug attaches to the contact point listed in the aircraft.cfg the AI Plane goes to PUSHBACK 2 and begins to move backwards.

States look like this

FLT Plan
Preflight Support
Pushback 1
Pushback 2
Pretaxi Out
Taxi Out

DanKH says

So I beg to differ that FSX doesn't use this parameter...

Dan you can go to any airport and set all Parking Spot Pushbacks to "NONE" (KMIA, 19a, EHAM, KJFK, EDDM, KATL, LEBL to name a few) and this has no effect on whether the AI Pushes back or not. FS9/FSX does not read this code into the dll file. There are many tags in the decompiled bgl (XML) that FS9/FSX has never used.

In FS9 MS did hard code some ramp parking spots with NO Pushback for GA AI type Planes but we were never able to duplicate that code regardless of how the pushback was set.

In our studies over the years we would have hoped that MS would activate these tags such as Taxiway Weight Limits, Pushback, one end runway usage, AI Plane Approach Transitions, more flexibility in approaches other then vector to final, timing for the theta meter values between TERMINAL_WAYPOINTS outside the IAF for better seperation then what is used and AI planes could use all the Holding Patterns that are written in the approach code just to name a few. There are many more.

Why not give us specifics for airports using the Traffic Explorer dll where you see pushback problems. That way others like Reggie and myself who study behavior can check to see if the problem with pushback is related to other issues that you may have or a problem with the default Parking Spot.
Hi Jim

I see your point here.

My problem was at a diminutive airport called EKAT.

I am introducing a small TAXI flight between EKRK-EKAT and EKLS and vicecersa. So nothing big here, but very good to get the feeling for FSX and the SDX including all the new wonderful "toys" here.

I use my own flightplan, and a 3. party (FS2002) aircraft.

Default airport (EKAT and EKLS) had no parking spots, no taxiways etc. etc. only a RWY.

So I added a few parkingspots (The pushback property defaults to NONE as you know in the ADE) some taxiways, a hold-short node, rwy taxiways etc. etc, all according to what's needed to get some AI in (and out).

Wrote the (VFR) flightplan and installed the "AFCAD". Started FSX up and watched my AI traffic both in FSX and in TrafficExplorer.

As I have mentioned the Parking spot had the Value NONE for Pushback.

There is NO airporttraffic, and as its a FS2002 aircraft, there is nothing in the aircraft.cfg either....

If I keep the NONE-value in the PushBack property the aircraft vanishes after preflight. If I set either LEFT, RIGHT or BOTH in the AI behaves completely as expected.

If you want all my "evidence" I'll be more than willing to send it over to you, aircraft, flightplan, traffic.bgl "AFCAD" the lot. Just give me a PM, or use my e-mail .. I guess you have it from our previous correspondences :)

Then you can yourself try to set in different values for the PushBack property and see the result.
I use my own flightplan, and a 3. party (FS2002) aircraft.
In my original post I said that Pushback is a hold over from FS2002.

MS has repeatedly said

backward compatibility, we cannot guarantee
and that includes going from FS2002 to FS2004 to FSX.

You have mixed and matched previous versions of FS into FSX and the rules are different for each.

If you place a FSX model.mdl AI Plane at EKAT and set pushback to "NONE" they will pushback. However you are using a FS2002 type AI Plane that the designer probably copied a FS2002 cfg/air/mdl set of files into his plane.

The FS2002 AI Planes DID NOT use a radius or half wingspan ft. value for pushback but relied on the position of the first blue node attached to the parking spot. The Model.mdl knows nothing about pushback distance in FS2002 so the old style txt coding was used which honored pushback=.

If you start putting FS2002 type AI Planes into FS9/FSX, the rules have changed and you must code a Pushback into your XML which is basically the same as the txt code previously used.

This is not the fault of FS9/FSX and it can be very misleading to everyone when you use noncompatible type model.mdl's that are coded differently in early version of FS.

Pushback = is not honored in FS9/FSX which is comparing apples to apples. If you elect to start going backwards (FS2002) then you must use FS2002 rules.

We have never understood fully why FS9/FSX kept Pushback in the XML/txt code and then not use it. Maybe you just answered that when you added the FS2002 plane to the FP.

Make sure your new EKAT has a holdshort node at the entrance of the runway. Mine does.

hope this is also helpful