There are a lot of bad instruments out there, flying in our 50+ year old planes.
For airspeed, I use the following rule:
The first time I fly any Coupe (or any plane), after the first
take-off, I'll climb to good altitude and find out the minimum flying
speed (or stall-break).
Then, just as it said in my first ground-school book, I multiply
by 1.3
and get a safe working approach speed.
Why:
My second flight in my Coupe nailed this home in my head! I got
my
license flying a 172 (and used that for my lessons). Right around
check-ride time, I bought my Coupe.
On the first flight in my Coupe, I did three take-offs and
landings --
OK. On the next day, I flew for a couple hours of cruise (mid-winter
temps at -5 to -10) and had ice melt from the tanks and refreeze in the
firewall gas-line. That stopped the engine.
My fourth landing in my Coupe, therefore, was with no power, off
airport, on a plowed field with 6-10" of heavy snow.
I nailed the approach speed at 70 for the forced landing because
that's
what the book and magazine articles said about my Coupe. (There were no
humans around to teach me, I studied and studied to learn about how to
fly my Coupe.)
Well, when I got to flare height, I pulled back on the wheel and
the
plane kind of leaned back a little with no flare and we hit! Gosh,
that's a tough landing gear! We rolled a short distance and stopped
with no damage.
I later discovered that ACCORDING TO MY AIRSPEED INDICATOR, THE
INDICATED MINIMUM FLYING SPEED ON THAT PLANE AND THAT INDICATOR WAS 65
MPH. With 70 mph approach speed to the forced landing, I had only 5 mph
above minimum with which to flare -- and it pretty much didn't.
Later I found the discrepency was due to a faulty air-speed
indicator.
Now, I do test each airplane I drive for this rather important number
based on its own airspeed indicator on that flight. And, I retest my
own plane every once in a while, too.
--
Ed Burkhead
East Peoria, Ill.
N3802H, 415-D
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