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Intersections: A question

Guest

How do you know you've hit one? I mean, they are not "real" (in the sense VOR stations are). Now, in flying here and there, sometimes I've used a VOR to find out.

i.e. Fly towards SYR, fly its 105 degree radial outbound (I get that for a chart) onto jetway R19. The segment is 15 miles long until it hits intersection VARIX. So, flying outbound on R19, once I hit 15 miles on the DME, I'm on VARIX. But not all intersections are on jetways (or victor ways) and I can't find radials for them on charts. So what's the secret?

P.S.1: The example's numbers are not correct necessarily, just illustrating a point.
P.S.2: Hope I made sense 😛

3 Responses

Pro Member Captain
Bindolaf Captain

Gah, it's not "Guest", it's me, sorry. Hadn't logged in apparently.

Pro Member First Officer
PH First Officer

The real secret is that airliners use the FMS! therefore cheating! Intersections are all given grid references (lat/long) and can be programmed into GPS if not already in the database. I have just been looking at a UK chart and see all intersections on an airway giving radial and distance to/from a VOR. Can you give me an example of one not being on an airway and the area or chart you are referring to. Can then let you know.

Don Wood Guest

An intersection is a precisely defined point in space formed by the junction of radials from two navigational radio devices.

For instance ORBIT intersection could be formed by the meeting of the 270 radial of XYZ VOR and the 180 radial of ABC VOR. NDB course lines can also be used so you might have an intersection formed by a radial from a VOR meeting a course line from a NDB.

Now that DME has become more common, points in space are also defined by DME distances on a radial (i.e., 16.3 DME on the XYZ VOR's 270 radial). While not technically an intersection, it serves the same purpose as it is a precisely defined point in space that can be used as a navigation fix.

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