wrote:

And these are FAA departure procedures? But not officially published
anywhere? Sort of makes it hard to comply with the FAR's on them then
Stan

They are established by the airport, not the FAA. They are not regulatory, but
compliance with them is because of the reg you cite. To cut to the chase, the FAA is
on the hook at a Class D airport because they exercise local air traffic control there.
Thus, by writing that reg that way they pass the buck to the pilot so they can have
peace with the airport management. At non-tower airports the feds stay out of the
fray.

It's all about noise.

Like Captain Moore says, you are already at the airport or you wouldn't need to know
about them for that airport. In the case of airlines, they attempt to document them in
their flight operations policy manuals. Generally, at busy airports, the noise
abatement departure is copatible with the ATC departure procedures (the IFR DPs that
are actually used).

At "Podunk" airports that do do have ATC DPs but have an obstacle DP sometimes there
can be a conflict. In that case, if the weather permits you fly the noise abatement DP
then transition to the obstacle DP. If the weather won't permit that you disregard the
noise DP and fly the obstacle DP. Generally, they understand that weather can create
an exception.