AOPA Pilot Magazine - August 2014 - 38

PILOT BRIEFING
|

PILOT PRODUCTS

Better safety,
softer landings
KLR 10 AOA review
B Y D AV E H I R S C H M A N
FINAL APPROACH SPEEDS in most GA
aircraft are a guessing game. The recommended speed is found in the pilot's
operating handbook, but that's calculated
at full gross weight. Then there's the timehonored practice of noting the power-off,
flaps-down stall speed (found at the bottom
of the white arc on the airspeed indicator)
and multiplying it by 1.3 to get a ballpark
approach figure. And if the wind is gusty,
add half the gust factor. As a result, our target speeds vary and tend to be based more
on habit and intuition than hard numbers.
Bendix King's new KLR 10 Lift Reserve
Indicator avoids the guesswork and helps
pilots fly more precise approaches, accounting for variables such as payload and density
altitude. Consistently better, and shorter,
landings are among the benefits.
We recently installed the KLR 10 system
in Editor in Chief Tom Haines' Bonanza
A36, an aircraft the staff uses for photography and company travel, and the KLR
10 light bar on the glareshield has quickly
become indispensable. Up- and downarrows are quick and easy to interpret,
and the AOA indicator's prominent placement means pilots don't have to divide their
attention between the airspeed indicator
and the outside world.
During a series of flights in which the
A36's center of gravity ranged from full forward to nearly full aft, and loads varied from
a single pilot and less than half fuel to four
adults and full fuel, the AOA indicator provided a steady and accurate guide during
approaches and landings. While flying the
optimum AOA, the target final approach
speed ranged from 81 mph when the airplane was light to 87 when fully loaded.
Transitions during roundout and flare, however, felt nearly identical.
In the five years I've flown this particular
A36, I've tended to approach too fast with

38 | AOPA PILOT August 2014

the resulting few extra seconds floating in
ground effect (and longer-than-necessary
ground roll) as the obvious consequence.
My rationalization was that slightly too fast
is better than too slow, and since most GA
airports have runways long enough to land
an A36 two or three times-using that extra
real estate hardly seemed like a tragedy.
But the KLR 10 will simplify future
trips to short runways, and it allows pilots
to keep their eyes outside throughout each
approach and landing. As my confidence in
the AOA indicator grew, the airspeed indicator became increasingly irrelevant. (The
airspeed indicator lets you know when it's
safe to lower the gear and flaps.)
The technology's real promise is reducing in-flight loss-of-control accidents in
which airplanes inadvertently stall and
spin. These often fatal accidents happen in
airport traffic patterns when pilots get distracted and allow their airplanes to get too
slow, turn too steeply, fly uncoordinated,
or take other actions that raise the angle of
attack to the "critical angle" at which the
wing aerodynamically stalls.
The FAA's Small Airplane Directorate
has taken the forward-looking step of allowing aircraft owners and pilots to install a
new generation of relatively low-cost, nonTSO angle of attack indicators with minimal
paperwork. (The KLR 10 has a retail price
of $1,600.)
It's the avionics equivalent to adding
seatbelt shoulder harnesses: It can't hurt,
and may help a lot.
EMAIL dave.hirschman@aopa.org

INSTALLING THE KLR 10
The KLR 10 comes with all the
required hardware, manuals,
and even a small screwdriver to
complete the installation and
calibration. The probe is built
to fit in an aluminum inspection
hole cover. It's exceptionally well
manufactured, and completely
independent from the aircraft
pitot-static system.
Fitting the probe to an inspection plate in the Bonanza's left
wing, routing the associated
plumbing into the fuselage, connecting the "interface module"
under the left seat, and installing
the AOA indicator took most
of one day. Then it was time to
calibrate the unit.
The calibration is a three-step
process that requires smooth
air-and that was in short supply
this winter and spring on the
East Coast. Our first few in-flight
calibration attempts were unsuccessful and required altering
the fixed angle of the probe.
That meant filing out a groove
in the inspection plate cover
and repeating the process. The
probe angle was reduced from
50 degrees to 45 and finally 40
before the calibration took hold.
Once completed, it never has to
be reset.
Also, for IFR airplanes, a
heated AOA probe is highly
desirable, since the tiny holes
that sense differential pressure
are susceptible to even trace
amounts of airframe ice.
Flying with the AOA system
brings home lessons that all
pilots learn academically but
don't always understand intuitively: namely, that an airplane
can stall at any airspeed and
any attitude. In a steep turn, for
example, AOA increases and can
easily reach the critical angle
at airspeeds far in excess of the
power-off stall speed. Also, it's
possible to exceed the critical
angle of attack even when pointed straight down, for example,
on the back side of a loop. (Note
to Tom: This is a purely theoretical discussion and I have not
been looping your Bonanza!)
The AOA education and constant awareness that the KLR
10 and other indicators provide
may ultimately be their most
enduring safety legacy.-DMH

AOPA Pilot Magazine - August 2014

Table of Contents for the Digital Edition of AOPA Pilot Magazine - August 2014