Help estimating altitude without altimeter?

On Oct 25, 9:30*pm, Darryl Ramm wrote:
On Oct 25, 8:51*pm, tstock wrote:



Hi, as a beginner I am still a little rough at this. *I've done 3
successful patterns with no altimeter, but today I failed one
miserably with my instructor. * There were two issues which threw me
off. 1) *we towed higher than the past attempts, and 2) instead of
entering the pattern at a familiar entry point, he had me circle
directly over the airport which made judging the angle a bit
difficult.

While we did eventually land safely, I failed miserably at setting up
the first pattern (way too high) and was forced to land on the
opposite runway (which left me way too low). *A little scary but a
good learning experience... one I do not care to repeat anytime soon.

I know I should be looking for the landing strip to be about 30
degrees below the horizon. *But how can I do this when circling
directly over the field looking down at it?

I made a second attempt and moved my circle so that the outermost edge
of the circle was where I would enter the downwind.. I succeeded this
time. *Unfortunately we also only towed to 1500' AGL which left me
with a much smaller chance of messing things up... so I can't say I am
completely confident despite the success.

Are there any easy methods for estimating the angle from the horizon?
For example a fist at arms length is 10 degrees, but obviously I can't
hold my first at arms length through the canopy. * The method I've
used is to wait until my aim point aligns with the outer most edge of
the air brakes. *To measure 45 degrees I look directly over the top of
my shoulder... *is there a better method?

Thanks
-tom

But but but...

You were flying with an instructor. Was this not addressed to your
satisfaction in the post-flight debrief? Its fresh in your mind then
and that's the time to get answers. Sorry but I cringe at these "where
was the instructor" questions on r.a.s.

If you are circling overhead you can use sized of common things (cars,
gliders, runway width (if known), runway markings, etc.) to judge
height. I think I saw some good slides on that once that Cindy
Brickner had.

But...You don't transition from just circling overhead to rolling out
on the runway. At some time you transition from that circle overhead
to picking up an the downwind or base or whatever leg and a relatively
steady state angle to the runway. Even if the whole approach is curved
your sight picture needs to transition from looking down to across at
that 30-45 degree picture. At that point if you look too high you
should be doing something about it, extend the leg, get on the
spoilers, slip, or all the above.

So you have at least two things to go over with the instructor.
Judging height from overhead and being on-top of altitude correction
in the pattern.

Darryl

BTW you can't use the horizon. It is hard to know where the true
horizon often is. What if you are in mountainous areas. In smoke or
haze etc. (which will cause enough problems with depth/distance
perception as is). Same reason you don't want to set up behind the tow
plane based on where the horizon looks. Even if you knew the location
of the true horizon you would not be able to estimate your altitude
from that to anything like a useful accuracy.

Darryl