Arrival Times: Accurate or not?

[Guest]

I'm just getting started with TTools and an AI Traffic Manager I've found here. I've gotten past the double saving of a/c flight plans, and now have a different problem. I've set up 1 aircraft, with 2 flight plans, originating in KTIX flying to KDAB (~20 mins away) then back again to KTIX.I've gotten the scheduling right, given it enough time to arrive and taxi before leaving again. Now my probelm is FS says after compiling that the a/c will arrive at its destination @ 01:24 and it actually arrives @ 01:34 +/- a minute or two. Why is this? It arrives at its previous destination with about 20 minutes to sit and wait for the next turnaround, so that isn't the problem. I've realized that giving the a/c 15 mins of turnaround time between legs isn't enough, and I now give 30 mins. The reason I ask this is because I want to setup a constant stream of arrivals into the airports I fly into, and I would like to time it so that they land ~3 mins apart from each other.BTW these flights aren't based on real world flight plans, I'm simply making them up.mw

[Guest lmoelleb]

How do you time the arrival time? I suspect the time you have in the traffic file is the time the plane would be over the airport if it just flew straigt at crouse altitude. But as in real life, the planes slow down when they descend, and have to be directed to the right runway. You will probably find that the arrival time depends on the wind (specially if different runways are in use)./Lars

[Guest]

I use AI Traffic Manager and it tells me the arrival time. I'll try it out some more and see if planes consistantly come in later than that time, that way I can plan.mw

[Guest]

>I've gotten the scheduling right, given it enough time to >arrive and taxi before leaving again. Now my probelm is FS >says after compiling that the a/c will arrive at its >destination @ 01:24 and it actually arrives @ 01:34 +/- a >minute or two. >>Why is this? It arrives at its previous destination with >about 20 minutes to sit and wait for the next turnaround, so >that isn't the problem. I've realized that giving the a/c >15 mins of turnaround time between legs isn't enough, and I >now give 30 mins. The 'arrival time' is estimated based on the 'crusing speed' you've specified in the aircraft.txt file. Obviously, if the a/c never achieves the stated cruise speed (say, the flight is short distance), the 'arrival time' isn't going to be very accurate! The longer the flight, the more accurate the predicted 'arrival time' will be.

[Guest Stamatis]

Your (and anyone else's) AI traffic is not actually flying the entire route.AI Traffic is only active in a rectangle (or is it circle?) of approximately 80 nm around your aircraft's location. Beyond that, there is absolutely no AI traffic flying.Thus, if you position yourself at an airport and expect arrivals, these will show up at or near their expected time, because the program will make them "appear" so as to reach their destination near their "planned" arrival time.This "planned arrival time" is simply the departure time plus the estiamted time required to fly over a Great Circle route to the destination at the cruising speed specified (regardless of whether the flight model in use can attain that cruising speed, and regardless of prevailing winds aloft) The program will simply calculate the time, and make the AI aircraft appear at the boundary of this 80 nm rectangle when it should. From then on, a lot will depend on actual traffic, runway in use, go arounds, etc., etc.Only time these "arrival" times go wary is if you stay constantly within 80 nm of the aircraft in question, (e.g by constantly following or leading it yourself)in which case that aircraft will actually fly the entire route "real time" and will arrive whenever it will arrive, depending on actual cruise speed, winds aloft, etc.Stamatis

[Guest]

>Your (and anyone else's) AI traffic is not actually >flying the entire route. >>AI Traffic is only active in a rectangle (or is it circle?) >of approximately 80 nm around your aircraft's location. >Beyond that, there is absolutely no AI traffic flying. Well, of course what you've said is factual, except for those flights that're confined to the specified radius. Of course, in that case the 'estimated time' will probably be bang on the money, since there's not as much room for calculation errors... :)One other problem, which I'm sure you've noticed, is that very often, those flights that magically appear on an arrival vector are most often at cruise altitude, such that they align with the rwny at FL130 (or whatever) and obviously have to declare a 'missed approach...' :)