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I work as ATC in Korea. And recently i have question about the exact meaning of the word 'intercept'.

In FAA order 7110.65, 5-9-1 vector to final approach course, "vector to intercept the final approach course", The Korean manual interprets the word of the sentence 'intercept' as "crossing".

I think the word 'intercept' means not 'crossing' but means the state just on the final, not exactly crossing but just 'established'.

The reason why i have question about this is that in the PAR approach, for precision approach, the final controller can vector aircraft to be exactly on the final beyond the faf although he started control in the state aircraft is not exactly on final.

So I think 'intercept' doesn't mean "crossing" but something else... Because I'm not native English speaker I want to know the exact meaning of the word 'intercept'. Please help me!

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Example: "ABC, turn right heading 020° for the intercept"‌​. – mins Jan 12 at 18:48

You are correct. The verb intercept, as used by ATC and pilots means to track to and then turn onto a given course. In your given example, "vector to intercept the final approach course", a vector to intercept is a vector which will cross the final approach course and from which the pilot will be able to commence a turn to become established on the final approach course. To intercept the final approach course means to accomplish that turn onto the final approach course.

See this additional example from an excerpt from Section 4 of the Aeronautical Information Manual (AIM)

5-4-3. b. 1.  

(c) The pilot is not expected to turn inbound on the final approach course unless an approach clearance has been issued. This clearance will normally be issued with the final vector for interception of the final approach course, and the vector will be such as to enable the pilot to establish the aircraft on the final approach course prior to reaching the final approach fix.

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I would reword is a vector which will cross the final approach course at a point where a turn onto that course can be accomplished. I would rather say: is a vector which will cross the final approach course and on which you will be able to commence a turn onto the final approach course. My reasoning is that your statement sounds like the point which intersects is the point where to turn, but you know that the turn commences before that intersecting point. – SentryRaven Jan 12 at 13:50
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@SentryRaven Excellent point, I will incorporate that change. Thank you! – Jonathan Walters Jan 12 at 13:56
    
Thanks to your answer but i have a doubt still. If ATC vectors aircraft to intercept final, and then the aircraft is not exactly on or crossing Final approach course(when looking aircraft at PAR) , is that case success to intercept or fail? I think this case is sucess(even not exactly on final approach course and crossing..) am i correct? – user12972 Jan 12 at 14:11
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@user12972, "exactly" is a matter of precision and the precision should be based on what the PAR controller accepts (I suppose they have some rule for that). – Jan Hudec Jan 12 at 15:32

In geometry, the point where two lines cross is an intersection, and the point where a line meets the axis (another line) is where it intercepts it. This is likely where these terms come from.

If you take the current location of the aircraft and extend the current ground track (the path) to the point where it intercepts the final approach course, that intersection is where the intercept occurs.

In ATC terms, when instructing a pilot *to intercept a course, you are telling them to transition from one course to the another like this:

Intercept Credit: Own work.

If they were instructed to not intercept the course, then they would be expected to continue on their original course (the black line in the picture above). Note that when a final approach course is involved in this situation, to be extra clear the phrase "vectors across final" is used so that they do not intercept when they aren't supposed to.

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needs at least one freehand circle – egid Jan 12 at 21:19

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