downwindabeam
9th Aug 2008, 18:30
Hello,
Do you know how SID/STARs and even Instrument Approaches are created...? Is there a simulator you can run the various terrain profiles and climb gradients needed to guarantee obstacle clearances ?
Also, how cna you simulate to provide a better throughput for a busy airport...?
Thanks!
-downwindabeam
galaxy flyer
10th Aug 2008, 00:19
Please refer to two manuals-In the US-TERPS (TERminal ProcedureS) and in most of the rest of the world ICAO Document 8168 Vol 2. TERPS is online, I believe, at the FAA site. Big download as is Doc 8168. Jepp's J-AID also has Doc 8168 in the international pages. Lots of clever formulas, trapazoids (being replaced with rectangles, thanks to RNP). These are the source of the "rules" on how to develop procedures. I wish I could provide links, but no, I cannot. In any case, fairly interesting (if you like geometry) as long as you are not tempted to use the information in bad ways. Like, "I know I have 250 feet of obstacle clearance, so I can cheat a 100 feet to get in".
What the FAA uses is a program out of an office called AVN-100 in Oke City. It has the obstacle database and lots more. The procedures designer can locate the precise reference points, like approach and departure ends, ARP, and overlay them on the surface of the local earth. Then he/she "runs" lines out to "find" obstacles that penetrate the Obstacle Indentification Surface. OIS is an important concept, the computer can only show what terrain, obstacles that penetrate the surface. Yes, he can mov) the the plane up and down, in the computer. Now, he can apply the TERPS rules to create procedures. Because TERPS calls for certain gradients, clearances, and turn radii, the designer can establish fixes (like an FAF or IAF) and altitudes (FAF crossing altitude, MDA, DA) that meet the requirements. The math computations is largely automated, but the designer has great latitude to make the procedures flyable or make the local ATC happy, etc.
Quite fascinating to watch procedures designed. The designer usually has some guidance from local operators as to what they need, from ATC (which is what largely drives SIDs and STARs) and the FAA (money for navaids, etc).
Then the procedure is flown, either in a sim or an airplane, to ensure flyability, then charting makes it a procedure. While the basic procedure design, once authorized, will take about a week to run in the program, it will take six months or more to publish it. ICAO procedures are similar, but the rules in 8168 are different. TERPS is often used outside the US, Korea and Japan, I believe, US Mil bases are TERPS. Countries can post exceptions to 8168, also.
No, they are not designed in a sim. But the AVN-100 program is run on a laptop, but looks nothing like aircraft sim.
GF