In voretaq7's answer to the question Is there a name for the area for aircraft to back track near the runway threshold?, it is mentioned that runway turnaround areas are considered part of the runway to which they are attached and that any aircraft in the turnaround zone are considered to occupy the runway.
I noticed that in the picture provided in his answer showing a runway turnaround area, the runway edge stripes actually included the runway turnaround area:
However, I've also noted that at the small, uncontrolled GA airport I've most often flown from, the runway edge stripes do not include the turnaround area:
Of course, in either case, a departing aircraft must cross the runway hold line and enter the runway to back-taxi to the turnaround area in the first place. However, I'm curious under what, if any, circumstances is it legal under the U.S. FARs for an aircraft to land or take off on a runway while another aircraft occupies the turn-around zone on that runway? And, of course, I'm talking about normal operations here, not emergencies.
- Does the runway edge stripe configuration matter, for example?
- How does this differ between controlled and uncontrolled fields?
For the sake of simplicity, let's assume that both aircraft in question are light GA aircraft, not aircraft whose wings might stick off the sides of the runway, and that all parts of the aircraft in the turnaround zone are on the turnaround side of where the runway edge line would be were it a straight line (like it is in the second picture.)
I have seen both landings and takeoffs with another aircraft in the turnaround area at the bottom field pictured above, including a couple of aircraft back-taxiing out there (under mutual agreement and while in radio communication with each other) and the second of them wait in the turnaround while the first takes off.