Alex Perry writes:
C172 glide angle is about 1.4 miles per 1000 ft, which implies the
canadian pattern gives you 300 ft to land with. However, that
doesn't allow for the plane to make the initial 90 degree turn
towards the airport and for the plane to align itself with the
runway. You need some more height if the runway isn't twice as
long as you need to land on. When you put that all together,
you're best 1/2 mile away on downwind.
I agree that closer is better, but you have left something out of the
equation: if the engine failure is sudden (what we're assuming here, I
think), *and* you react quickly, you have an extra 25-45kt of airspeed
that you can trade for altitude before you get down to Vglide at 65
KIAS. That should be enough to hold circuit altitude through the
90deg turn and even a little on towards the runway.
I've been able to glide back from downwind during engine-out exercises
without much trouble, except once when I was a little too far and
there was a strong opposing wind (I had to add a little power; in real
life, I would have set it down on the golf course under the 22
approach). Note that our circuit altitude is 1,100 ft AGL, so I had a
10% bonus, but most times I did have to apply flaps on short final to
get down, negating the bonus; I can also fly downwind at 100-110 KIAS
when I'm not following a C150 or Katana, and that helps as well.
In fact, I'm lucky when I can get even 1 mile from the runway on
downwind. I've noticed that some other pilots have gotten into the
habit of waiting until they're at circuit altitude to turn downwind:
that works well enough for a 150 or 172 on a cool day, but on a hot,
humid day, it puts you two miles or more out from the runway on
downwind and everyone else is forced to follow you (muttering and
cursing).
Yes. Also, the Canadian pattern has you fly a longer final. For
grins, try taking the engine to idle, as you make the downwind to
base turn, and see how close you'd get to the airport. You barely
get half way. The american pattern (for light aircraft) has a
fairly short final.
It would depend on the wind, of course -- remember that we're still at
full circuit altitude and speed at the start of the turn to base. The
other day, ATC gave me a sudden direct-to-threshold instruction during
my base turn to get me down ahead of some other traffic, and I had to
close the throttle and apply full flaps just to get the plane down to
the threshold. With a strong headwind, though, I agree that I
probably couldn't make it as easily. Also, in a C150, which doesn't
glide as much, it would be a much bigger problem.
Naw, we're used to visitors from up north, even down here. We'll
hear the funny accent on the radio [*] and keep out of the way.
8-)
The Canadian pilots are the ones who say thank you for every
clearance (in the 1980s, SPY magazine said you could spot Canadians in
New York because they say thank you to bank machines).
* Actually, your callsign will be Canadian Alpha Bravo Charlie.
A little longer, at least on first contact -- Canadian Charlie Gulf
(or Foxtrot) Alpha Bravo Charlie. Apparently, American controllers
have a tendency to add a November before Canadian callsigns, just
out of habit.
All the best,
David
--
David Megginson, [EMAIL PROTECTED], http://www.megginson.com/
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