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I am working on an en route air traffic control system. For the application I plan on allowing the user to plot the position of a few waypoints on a square region which is 100 miles in length and width. The aircraft will then follow a route which passes through the relevant waypoints. Therefore, I would like to know whether there is a general estimate for the distance between 2 adjacent waypoints so that I could have rules for where the waypoints can be plotted and how many of them can be plotted in the whole region.

Thank you very much for the help!

Maths2468
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    Great circle? Rhumb Line? Vincenty? What world model do you want to use? You would use formulas such as those to find out the distance between two waypoints. – Ron Beyer Oct 22 '18 at 00:18
  • I apologise for not making this clear, but the application is a simulation and for the purpose of the simulation the region will be represented using a cartesian coordinate system. Therefore, the distance between waypoints would just be the euclidean distance between them. So, I just wanted to have a vague estimate for the distance between them in real life for e.g. if it 50-100 miles or 5-10 miles. – Maths2468 Oct 22 '18 at 00:32
  • Ok, so the difference in position in X/Y cartesian space is just the values subtracted from each other... I'm still not sure what you are getting at? Can you give an example of the coordinates and what you expect the value would be? Why do you want an "estimate" vs the actual value (which is easier to calculate than "estimate")? – Ron Beyer Oct 22 '18 at 00:37
  • Well, the main reason for this question is so that I can put a limit on how many waypoints can be input by the user. The purpose of the application is to show that it will automatically predict future collision between airplanes and make decisions so that the collision can be avoided. This feature is quite resource hungry. If there are many waypoints then the application would need to do more work to find the final position of the plane after a certain amount of time than it would if the plane was travelling in a straight line throughout its journey. – Maths2468 Oct 22 '18 at 00:52
  • So to make the simulation realistic and possibly faster I wanted an estimate of the distance between adjacent waypoints in real life. I can use this to set some rules for the user when he/she is plotting waypoints. – Maths2468 Oct 22 '18 at 00:53
  • waypoints in real life have no standard distance apart from each other. Some are very close (10 miles apart or less) and some are much further apart (80-90 miles apart or more). This depends entirely on the route structure you are dealing with and the type of procedure. For example enroute at altitude, arrival/departure (like a STAR) or even instrument approaches. Look up the definition of a Standard Terminal Arrival (STAR) and view what one looks like. A STAR often will have a bit of an enroute transition into a terminal area with lots of waypoints to look at. –  Oct 22 '18 at 00:58
  • Why not go to a site like www.skyvector.com and pick a 100 mile x 100 mile area and see how many waypoints there are. Airports only? + VORs? + Intersections? +NDBs? Those would be the waypoints most pilots would use for navigating with. – CrossRoads Oct 22 '18 at 01:00
  • Okay, I will have a look at the STAR and skyvector.com and use those to decide on a minimum distance between waypoints for my simulation:) Thank you very much. I really appreciate the help! – Maths2468 Oct 22 '18 at 01:09

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The distance between waypoints on a procedure or airway can vary tremendously. For waypoins on a high altitude airway, over 100 NM is common. For low altitude Victor airways, less. For an instrument departure or arrival, 10 to 20 miles is common, especially near the terminal area. On an instrument approach, legs are almost always under 10 miles. So the limit for your application depends on what sort of airspace you're modeling. At 100NM square, that's more nearly the size of a terminal area than an enroute sector, so 10 to 40 miles is probably a reasonable ballpark.

Might be worthwhile to order an actual IFR enroute chart - they're only a few dollars, and then you have a real example of what airspace actually looks like. Or, any of the free flight planning websites can show you essentially the same thing on-line.

Ralph J
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