# "Report a 3 mile right base" - where is it measured from? [duplicate]

At which position should you report to ATC?

• How long a base leg would you actually be flying in the "position 3" case?
– user
Mar 14 '19 at 16:02
• This IS a duplicate... Mar 14 '19 at 20:10

It's neither of the above, it's a base leg which will converge onto the final approach leg 3 miles out from the runway threshold. In other words when you turn from base onto final you'll be on a 3 mile final.

• Do you report when established on the base that will intercept final at 3 miles? Mar 14 '19 at 16:34
• I've never been told to report on a 3 mile base before, but if I was I would report when established on the base leg as the key part is to report on base.
– GdD
Mar 14 '19 at 16:37
• How is that different from "Report a 3 mile final"? If you're turning base-to-final, or just on final, you're at the same position, 3 miles from the threshold, just on a different heading. Mar 14 '19 at 17:51
• The difference is that the controller wants to know when you enter the base leg, not when you are on final @abelenky. Maybe it's important for separation. I'm not convinced this is standard phraseology.
– GdD
Mar 14 '19 at 18:27
• I like this answer. I'd like even more to see if there is a source. PC glossary? Mar 14 '19 at 20:01

A "3-mile base" means a base to 3-mile final, with downwind being at the normal distance from the runway; it's named that because it's the base leg that moves.

All of your positions are based on the idea of a 3-mile base to (normal) final, which would mean the downwind (not base) has moved. If that's what they wanted, you would get an instruction to simply "enter right base", regardless of how far away that may start, and possibly some other reporting instruction if they're non-radar.

Also, position 1 doesn't really make sense. If you called in north or northeast of the field, they would tell you to "enter downwind", so position 1 shouldn't happen. If you were already in the pattern and they wanted you on a 3-mile final, they would tell you to "extend downwind" and either tell you 3 miles (or a landmark 3 miles away) specifically or, more likely, tell you what traffic to follow.

If you called in east or southeast of the field, tower would assume you're in position 2 or 3, not position 1, because any sensible inbound caller would have their nose pointed either at the field generally or at whichever leg of the pattern makes sense given the runway in use (i.e. wind) and their position.