I found this on the rec.backcountry group...

The Grand Canyon Hikers and Backpackers Association (GCHBA) supports
implementation of substantial restoration of natural quiet as defined
by the National Park Service and interpreted by the courts.

The GCHBA Board encourages you to submit your comments based on your
own views and concerns about air tours and aircraft noise to the FAA by
April 27, 2006. This is a very important issue that concerns all of us
that love the Canyon. One of the air tour operators has gone so far to
as to propose to the FAA that hiking and camping be banned in the areas
(such as Hermit Basin) where they conduct their tour flights. The tour
operators have flooded the FAA with comments from their customers in
favor of their operations. The new overflight rules can have a large
affect on our enjoyment of the Canyon.

See http://www.gchba.org/overflights.asp for our position statement and
http://www.gchba.org/overflight_submit.asp for a partially pre-filled
form for submission of your comments to the FAA.

Hikers - GCHBA represents the hiking community with members sharing
their experience through the Internet. Hikers are a smaller number than
some other groups involved in the overflights issue, but we are in the
10s-of-thousands each year and this is more than people realize. For
many, their trip to Grand Canyon is the `trip of a lifetime' - the
same as for other visitors. Over the years, the number of individual
backcountry hikers is in the millions.

Aircraft -Our proposal regarding flights over Grand Canyon is simple,
that there should be no aircraft over Grand Canyon except for essential
services (emergencies and other essential operations). Some people seem
to be offended by a proposal that they disagree with. A proposal is
just that: a proposal, not an action, not something to be offended
over. One of the most dangerous places to pass in Grand Canyon is
Crystal Rapid. You row as hard as you can for the north shore, and even
if you row as hard as you can you will never get there. But if you
don't row as hard as you can you may not get to be what we call `ABC,'
Alive Below Crystal. Making any proposal takes courage and involves
risk. GCHBA will sincerely review and consider every proposal.

Specific things we are looking for include: A quiet period in Hermit
Basin because this is a popular and accessible area. Some degree of
adjustment to jetliner routes because the noise model shows all of the
Park is affected now. Compliance reporting - recording tour aircraft
with on-board monitoring will improve the credibility of flight rules.
Sensible implementation of `no flights below the rim' - when we see a
helicopter with a cliff behind it and hear the sound coming back at us
from that cliff, it does not make any sense that this is `no flights
below the rim.'

Quiet - We intuitively understand the spiritual significance when
Native American speakers say that "what happens at Grand Canyon affects
the whole world." People come from all parts of the world to experience
Grand Canyon and they carry that experience back with them to all parts
of the world, and that experience must include natural quiet.

Water - The places in Grand Canyon where there is a good water source
are the most important to us. Every hiker must plan their trip around
where there is reliable water so these are the places that we go to
most often and these are the places that we would most like to see
protected.

Closures - We have heard about areas that have been closed to
flights, and hikers have to accept closures also, and we do. These
closures include road access to trailheads, cultural sites that have
been identified that we avoid, Native American lands where there was
little concern where we went but now we need to educate the hiking
community to respect these boundaries. We all share the obligation for
any type of closure, in the airspace or on the ground, for the future
protection of Grand Canyon.

The GCHBA Board of Directors
http://www.gchba.org