On Sun, 30 May 2004 21:58:12 +0200
Durk Talsma wrote:

> I hadn't really thought about that so much. However, while these SIDs and 
> STARs wouldn't be very useful for AI traffic, they probably wouldn't be too 
> problematic either. As long as there is an initial and a final waypoint, the 
> "expect vectors"  would then simply be the most direct route between these 
> two. 

More precisely, you can define some arbitrary waypoints. For instance,
if the SID says climb to zzz ft, you can determine the point (distance)
at which the aircraft reaches that altitude, and have it marked as a
waypoint in the internal AI flight plan. The next waypoint would then be
the first en-route waypoint. Likewise, if the STAR says "expect
vectors", and if you are supposed to go for an instrument final
approach, you can safely assume that ATC will try and vector you to a
point approximately 4-6NM before the Final Approach Point, on the same
axis as the final approach.

> I'm currently again leaning more toward a "straight-in" "straight-out" take on 
> AI traffic as the first step, because that would simplify automatic flight 
> plan/waypoint generation by quite a bit. Then next, if we have the data 
> available on approach and departure procedures, these could be used instead. 

And that's more or less the way it works in real life, usually the first
step is writing the flight plan, and for this you usually try and find
SID and STAR flight paths. If you can't find them, you fall back on
direct-to-waypoint-type paths.

A good thing to do would be to try and implement the way ATC works as
close to real life as possible. You can define these default flight
plans for AI aircraft, and implement a "clearance limit", which means
that the aircraft can follow the flight plan safely up to a given point
(usually a waypoint); you can also have altitude clearance (usually in
order to avoid other traffic). Before reaching a clearance, an AI
aircraft could "ask" for further directions/clearance from the ATC. If
the ATC has a radar, it can detect that the aircraft is approaching the
limit and give further directions without having to be asked for them.

You might be interested in the rules of ATC (traffic separation using
time or distance or altitude), most of it should be in the ICAO document
4444. I don't know where to get it, but I had been given one while I was
preparing for the ATPL theory exam. I did a little search with Google,
and apparently the document (official title Procedures for Air
Navigation Services - Air Traffic Management or PANS-ATM, ICAO document
number 4444) is for sale for $161 on the ICAO website...

Jorge Van Hemelryck

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