Border for downwind and base?

when controlling a tower, which is the exact boundary between the base and downwind? anyone can help me please? I consider downwind until the end of the ILS, from then on for me is based, is correct?


This should help:

It’s not exactly the border line but what position in the pattern. The aircraft could be 1 mile from the airport on the base, or 5 miles.


I think the optimal downwind is about 2NM from the runway centreline/extended centreline

I know this,but my answer is:when a plane is btw b and dw what will be my enter sequence?

from what I know usually on a downwind leg is flown a half mile to a mile parallel to the runway then wants you are at a 45 degree angle with the numbers on the runway you make a turn from downwind to base. You know you are on base when you are flying perpendicular to the runway. All turns in the pattern should be 90 degrees and should make a rectangular course. Im sure @Mark_Denton can offer more knowledge then me.


I think your trying to ask something other then what you asked. Are you asking what pattern entry you should give based off of distance and proximity to the runway?

ok now I’ll explain, look at the picture, plane 1 is dw, right? Plane 2 is base or DW?

Downwind. It would only be base if plane 2 was facing the localiser.

So depending just and only if the plane is facing to the runway?not depend if is until ils limit?

If the arrows for the planes are their direction they are both on downwind

So if plane 1 os facing to runway is on left base?although it is close to the runway?

Ok so here is a layout of the pattern. On the plane turning base you can consider him on base when sequencing but not before the turn. Patterns can be anywhere from .5 mile to 15 miles from the airport. So distance doesn’t matter only direction of flight.


Bravo !!! finally !! This is what I need! Now I’m ready for any test thanks !!!


What @Brandon_Sandstrom drew out and stated is the correct information that you are looking for. The pattern for a 172 is going to be different than a fighter jet/trainer, commercial aircraft, etc. The concept (legs) of the pattern are the same; upwind, crosswind, downwind, base, and final. The distance and altitudes will vary depending on the aircraft.

I’ve been in the pattern with a DC10 before that was doing touch and go’s after some maintenance. They turned final everytime 8-10 miles out where I would turn base whenever I was basically at a 45º angle from the threshold.

Thanks Brandon for your [professional] illustration and explanation. Haha

  • Skyhawk Heavy

@Mark_Denton I never said I was an artist 😂


LOL You didnt have to say it either.


Hey I got the point across that’s all that matters 😜

1 Like

Thank you very much guys I think that I resolved my issues!🙏🏻👍

Here is an illustration I’ve made to help provide a visual for an airliner pattern.

Hope this helps!

-Skyhawk Heavy


So practically in the moment when you turn base you are in l/r base,regardless if you are at 1 or 6 miles from the runway? while same thing for the r / l if downwind if you are parallel to the runway you’re always downwind, right?