For [email protected]

It is apparently not possible to communicate with you directly, so let me
explain how I got the 1.4 miles of protected airspace on the non-maneuvering
side of procedure turn airspace, and apologize for being wrong...the
protected airspace is 4.0 miles wide, giving the pilot even less reason to
work at tracking the outbound.

Back when TERPS was an actual publication with pages rather than an online
source, Para 234 included instructions for constructing procedure turn
airspace based on max allowed distance. In the instructions for a ten-mile
PT, the procedures designer was told to select a point one mile inside of
the airspace on the manuevering side, perpendular to the outbound course at
the fix. The next step was to select another point, ten miles from the
original point but two miles inside of the maneuvering airspace. The
designer was then told to swing an arc with a 5 nm radius from the first
point and a 6 nm radius from the second point. A line drawn tangent to these
two arcs, parallel to the outbound course, defines the edge of the primary
protected area on the non-maneuvering side. The primary area gives 1000 ft
of vertical clearance...beyond that, the protected airspace vertical
protection tapers down to zero over an additional two miles.

Can't find the detailed instruction in the online TERPS, but the
illustration remains.

Bob Gardner