AI traffic strange problem

[Chfeudpail 0]

ok very good , but do I need to put 200 kts to every bgl or just a few would do the trick to regain complete arrivals ?

 

And a cruising speed of 200kts is pretty weird for most airliners !

 

I still have some issues regarding some planes trajectories , some seem to fall from the sky , landing before the treshold , others are too high ....

[pschlute 37]

ok very good , but do I need to put 200 kts to every bgl or just a few would do the trick to regain complete arrivals ?

 

And a cruising speed of 200kts is pretty weird for most airliners !

 

If you use a flightplan that has @ before the arrival time, and you are using TTools to compile then you need 200 for jets and a lower speed for props. As i understand it the AI system has two things to look at as far as arrival times go:

 

1. The arrival time in the flight plan eg. @5/08:15

2. Its computed arrival time : distance x aircraft speed

 

If you put the correct cruise speed say 485knots in the aircraft.txt file and the AI engine computes that the specified @arrival time is too "late" it will not show the a/c arrriving and simply populate it at the gate. Using 200 knots will ensure that the @arrival time is always "early", as it will be well before the computed arrival time, and so will display the a/c ariving and landing. People far more clever than me have worked this out, and you will find a lot of detail in the AIFP manual.

 

If you use a flightplan without the @ arrival times then you can use the "correct" speed in the aircraft.txt file, as the sim will calculate arrival times.

 

AIFP does it differently again and uses the correct cruise speeds in the aircraft file. This is why you need to check carefully the format of your plans before you compile them.

 

As far as your ai is concerned you have only fixed Delta and Spirit...lots more to go !

[Chfeudpail 0]

I've done some more airlines now but just to make it clear , if I now start using AIFP as the compiler I shouldn't worry about acft speeds anymore ?

 

So then I'll drop TTools for AIFP.

[pschlute 37]

I've done some more airlines now but just to make it clear , if I now start using AIFP as the compiler I shouldn't worry about acft speeds anymore ?

 

So then I'll drop TTools for AIFP.

 

You will need to worry if the flightplan creator has used a TTools format and used 200 as the a/c speed....you will need to change that to something more correct. But the AIFP manual explains all.

[Chfeudpail 0]

Thanks , and how come I see like 1 out of 4 planes being landing much before the treshold , they are advancing on the ground miles away from the treshold...

[pschlute 37]

Someone more knowlegable than me will have to answer that one. I have seen it very occasionally.

[Dave Morgan 68]

Hi.

 

If you use a flightplan that has @ before the arrival time, and you are using TTools to compile then you need 200 for jets and a lower speed for props. As i understand it the AI system has two things to look at as far as arrival times go:

 

1. The arrival time in the flight plan eg. @5/08:15

2. Its computed arrival time : distance x aircraft speed

 

If you put the correct cruise speed say 485knots in the aircraft.txt file and the AI engine computes that the specified @arrival time is too "late" it will not show the a/c arrriving and simply populate it at the gate. Using 200 knots will ensure that the @arrival time is always "early", as it will be well before the computed arrival time, and so will display the a/c ariving and landing. People far more clever than me have worked this out, and you will find a lot of detail in the AIFP manual.

 

If you use a flightplan without the @ arrival times then you can use the "correct" speed in the aircraft.txt file, as the sim will calculate arrival times.

 

 

Almost, but not quite...

 

If you place a @ before the arrival time then you can specify any cruise speed you like and Traffic Tools will ignore it when recompiling, using its own calculated value instead. This is useful if you wish to adhere to a set timetable.

 

If you do not place a @ before the arrival time or if you simply leave that field blank

(e.g. AC#4,N29696,56%,12Hr,IFR,01:46:21,,320,F,2953,KLAX)

then your cruise speed must have an appropriate value to ensure AI arrive at a sensible time. This is useful if you wish to have accurate cruise speeds.

 

I would suggest that if you are following real-world schedules, you need to place the @ in the plan or your AI may turn up early or late, leading to frustration when you are spotting.

 

From the Traffic Tools documentation:

 

Arrival time:

 

This is the estimated time of arrival at the destination airport. This can be used in two ways: compiler calculated arrival times or user defined fixed arrival times.

 

By default, this field will be calculated by the compiler and you do not have to fill it in. In fact, the compiler will ignore anything you put in this field so you can just leave it blank (e.g. ,00:00:00, or just , , ). When the compiler calculates this value it is actually the arrival time in the airport’s airspace. The arrival time at the gate or parking space will be about 15 minutes later, after landing and taxiing. When you compile TTools will automatically insert the calculated arrival time in this field, and you can re-open the FlightPlans file to see the arrival times. The compiler calculates the flight time using the distance between the two airports at the specified cruise speed for the aircraft.

 

Alternatively, you can specify a fixed arrival time by preceding it with a ‘@’ symbol (e.g. @11:26:00 or @6/22:13:00). In that case the compiler will calculate the cruise speed required to make the aircraft arrive at the specified time for that leg of the flight plan, regardless of the cruise speed given for the aircraft, or the cruise speeds used for other legs of the flight plan. When you use a fixed arrival time then it will actually specify the arrival time at the gate, give of take a few minutes, and not the arrival time in the airspace as with a compiler calculated arrival time.

 

Kind regards,

D

 

edit: I'm unsure whether either format allows AI to be susceptible to weather. Does a fixed cruise speed cause delays with headwinds, and early arrivals with tail winds? I've never experimented; maybe someone else here can answer that one.

D

[mebull 27]

Thanks , and how come I see like 1 out of 4 planes being landing much before the treshold , they are advancing on the ground miles away from the treshold...

 

That is also a known issue with some AI models and their flight dynamics. It is most noticeable when you first start a FS9 session but may happen at any time. The two behaviors are AI diving into the terrain and AI "landing" well short of the runway. Example: You are at KATL observing, the AI engine plus flight plan has determined that a Delta B744 is scheduled to land at XX:XX:XX time. At a time the AI engine determines is correct it 'spawns' the aircraft at +/- 40nm. The cruise altitude of the AI is set for 39000ft, so the AI has a very short time to loose all of that altitude so they dive like a incoming meteor! Some AI aircraft because of their design (which isn't really faulty) can't pull up in time and disappear into the terrain. Others may recover and pull up in time to avoid the terrain and be able to line up with the runway for approach, however they have fallen below the altitude where the normal approach descent would begin. Again, if they are not lined up with the runway they will 'land' into the terrain and disappear, if they are lined up with the runway they will 'land' into the terrain and travel over the the river and through the woods, mountains, buildings and anything else until they arrive at the runway, stop and exit the runway like nothing bad happened. AI are designed to look good on the ground at the gate and during taxi, look realistic as they take off, and look realistic as they approach and land, stop and exit the runway. Everything else is a compromise to meet those goals. BTW this also explains why you never see a light aircraft, like a commuter or a general aviation aircraft exhibit this problem - lower cruise altitude, lower cruise speed and lower weight factor.

 

Regards,

Mel

[sonebone 0]

just to be sure you change air speed in the aircraft file or Flightplan file? I may of had this wrong.....Thanks

[Dave Morgan 68]

Good morning.

 

just to be sure you change air speed in the aircraft file or Flightplan file? I may of had this wrong.....Thanks

 

Decompile your ai traffic bgl into three text files: Aircraft.txt Airports.txt and FlightPlans.txt

 

Alter the cruise speed in Aircraft.txt... there is no cruise speed specified in Airports.txt or FlightPlans.txt

 

From memory it's the second field, after AC#1 or AC#2 or whichever plane you want to modify. Don't alter the actual aeroplane's config or air files.

 

re. Mel's post, again. That's also why planes designed as player aircraft don't always behave as hoped when assigned to AI traffic.

 

Best regards,

D

[Chfeudpail 0]

Thanks guy's for your good help !

 

I have now partially recovered my long landing queues . As from now I'll change the speeds to 200 kts whenever I install a new flight plan as they seem all to have these @ arrival times....

 

 

Cheers !!!!

[sonebone 0]

So I went in and changed all the flight plans to speeds of 200 and less and still no landing aircraft nor do i see any aircraft in sky period. I am thinking some file must be missing or something may not be turned on that needs to be that controls landing AI...Very fustrating any other thoughts? Thank you

[JSkorna 137]

Did you generate a .bgl file and is the file in FS somewhere?

 

Are your traffic sliders at 100%?

[pschlute 37]

.....and what program are you using to create the .bgl ?

[sonebone 0]

TTools. which is why I changed to the 200knts ( I read earlier on this thread that there is a ttools bug. To correct this you have to decompile and change the speeds) and after I changed the speeds I recompiled the texts to a traffic bgl which is then placed in my scenery world scenery file