Larry,  I feel most comfortable flying my iv-p- at the upper teens partly
because I have the option of flight following or instruments if I choose,
but I am reasonabley comfortable up to FL250 because I've been there a
number of times before and it is still low enough that I think I have more
options than I would at FL290 in an emergency.  One thing addressed during
the high altitude endorsement given to me by the person who use to run the
altitude chamber here in Colorado Springs is paying attention to Mach
numbers.  He pointed out from the graph in the iv -p POH that the Mach
number at FL290 is about 195 kts indicated, ie above that air speed you are
exceeding Vne.  I think flying at FL250 over overcast is a different
decision particularly if there is icing than flying at the same altitude

because if the cloud deck rises you are forced higher and you have fewer
options.  The other thing I learned during the high altitude check out is
that having enough standby oxygen to fly another hour is a real advantage
because at 300kts TAS  you can often find better weather conditions if you
are caught over unfavorable IMC. As the article points out the time of
useful conciousness is three to six minutes at 25,000' vs. 30 min. at
18,000'.  So in answer to your question I think I like flying in the high
teens but I can be lured up into the flight levels by favorable tail winds
and good weather.  Other's thoughts?  Also, a question for the group:  Is
there any logic to pressurizing the cabin to 3.5 to 4 psi rather than 5psi
thinking that the cabin is being physically stressed less and less of an
explosive decompression if that should happen?  Incidentally,  I didn't
pressurize for a few months!  It took that long to get all of the leaks
plugged!  Good luck with the maiden flight, that's a great day.  John
-----Original Message-----
From: Larry Klaas <ldkatbend@transport.com>
To: jwrightdo@worldnet.att.net <jwrightdo@worldnet.att.net>
Date: Sunday, February 13, 2000 3:47 PM
Subject: AV Web Article

I'm about 45 days from my first flight on my 4P.  Read the AV web article
you mentioned.

So how high do you fly now after reading it?

Larry Klaas
21725 Rickard Rd
Bend, OR 97702
Tel: 541-389-2900  Fax: 208-361-5849