# How could I calculate the correct distance from the runway to be able to fly a continuous downwind to final turn?

I’m not even sure if this is a safe/allowed procedure at controlled airports so it is purely hypothetical.

Assuming there are calm winds at the field, is there a way to calculate the distance your plane must be from the centerline (see “x”) of the runway while on downwind, so that once you start your turn to base and final thereafter, in a constant rate turn (assume 3 deg./sec.), that you will end up rolling out on the centerline of the runway?

Speed changes (slows) by 27 knots from the beginning of the turn to the end of the turn.

Essentially, if I wanted to execute an 180 degree turn at 3 deg. per second, while slowing the airplane from traffic pattern speed (90 kts) to final approach speed (63 kts), how far away would I need to be from the runway while on downwind before beginning the maneuver? The goal is to be able to use this on any plane given their own specific traffic pattern speed and final approach to landing speed.

• This really isn't a standard pattern, why would you do that? You don't want to be turning and making configuration changes while turning, it's one of a few reasons you don't make a semicircular approach. Commented Aug 9, 2019 at 1:07
• Although it is not common in the civilian world, I believe procedures like this are quite common in the military. Specifically the Navy. Commented Aug 9, 2019 at 19:22
• FWIW, there was a study planned on this, although I never heard about the results. As per another comment, this is common in the military world, including civilian pilots who fly ex-military aircraft. Commented Aug 9, 2019 at 23:50