Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!stanford.edu!neon.Stanford.EDU!news
From: news@solitary.Stanford.EDU (System test)
Newsgroups: rec.skydiving
Subject: Re: High altitude landings
Keywords: hang gliding comparison
Message-ID: <1991May16.164338.6112@neon.Stanford.EDU>
Date: 16 May 91 16:43:38 GMT
Sender: news@neon.Stanford.EDU (USENET News System)
Organization: Stanford University, California
Lines: 26

Someone asked the question of how landing a parachute at 9500 MSL differs
from the behavior at sea level.  It's already been mentioned that the only
real difference is that all the speeds (descent rate under canopy, forward
speed and speed to flare) increase by the square root of the the ratio
of air densities - or about 20% at 10,000 ft.

While I've not landed a parachute under such circumstances (only paragliders
at or near sea level), I have landed hang gliders at high altitude and think
the experience is similar enough to be germane here.  Specifically, while
20% doesn't sound like much it can really affect your flare timing
significantly.  I tend to flare by the "feel" of the wing (i.e. its readiness
to stall) but nevertheless I sometimes inadvertently use ground speed as a
secondary cue.  This is a bad thing and can make one flare way too late if
it's not recognized.  Landing at high altitude when done properly is just
as "soft" as on the sand at the beach, but requires an earlier more aggressive
flare at a ground speed that always looks "too fast".  Be aware of this factor
and you should do fine.

I guess the best comparison I can make is to note that a high altitude landing
is a lot like a dead wind landing on a hot runway at low altitude.  
If that experience seems straightforward to skydivers then a landing at 
10K ft ought to be as well.

Later,
Fred Vachss
(one of those guys who only wears a parachute but never uses it)