AOPA Turbine Pilot Magazine - July 2022 - T-6

/ TURBINE PILOT /
Too many toggles
Rows and rows of toggle switches
BY J. MAC MCCLELLAN
EXPERTS CAN KNOW THE AGE of a horse by counting its teeth. Pilots
can identify the age of an airplane design by counting the number
of toggle switches on the instrument panel. I think about that
every time I'm taking the runway in the recently manufactured
Beechcraft King Air 350i that I fly. The King Air by toggle count
wins the Methuselah design award.
There are 14 individual toggle switches to flip to ready the
King Air from taxi mode to takeoff. And if the weather is cold
and crappy, there are three more switches to fumble with. And all
but two of the toggle switches
are identical in size, shape, and
color. They are lined up along
the pilot's subpanel as indistinguishable
from one another as
white keys on a piano.
Working from left to right
the switches control engine
auto ignition; engine ice protection;
auto feather operation;
landing lights; strobe lights;
recognition lights; pitot heat;
fuel vent heat; and stall warning
heat. And if icing is possible
for takeoff you need to flip
switches for windshield and
propeller heat.
Compare that to any
recently designed turbine airplane
where you find air data
system heat controlled by a
single switch, even though jets
have three pitot tubes compared to the King Air's two, and in jets
the static ports are heated. Landing lights are on one switch, often
a two-position switch to select taxi or takeoff/landing mode. Who
wants to turn on a single landing light at a time anyway? Only King
Air pilots, I guess.
The King Air panel design and multitude of toggle switches
dates to the first model built in 1964. And that first King Air 90 was
really a turbine conversion of the piston powered Model 88 Queen
Air, so the panel design has roots even many more years in the past.
T-6
AOPA PILOT / July 2022
In the bad old days of airplane design human factors considerations
didn't exist, or, if thought of, received the lowest priority.
The most direct and uncomplicated way to design a system was
to have an individual switch control a single function. And toggle
switches can also function as circuit breakers, further streamlining
the design and construction of the airplane.
Cessna was among the first to give " switchology " at least some
consideration when it developed the Citation. Functions were
grouped into a single switch, or at least fewer switches. And Cessna
located operational category
switches-such as ice protection,
or lighting-into logical
groups on the panel. They
also added color-coded covers
on the switches to aid in function
identification.
More recent cockpit
designs use lighted pushbutton
switches the show the position
of the switch in plain language,
or better yet, remain dark
when all is normal. Before
LED lighting these switches
didn't work so well because
incandescent bulbs got so hot
they burned pilots' fingers.
In the newest cockpits
switches of any type are few
because touchscreens control
nearly all systems and
are smart enough to know the
phase of flight and what systems need action.
The King has reigned since 1964 and has been built in greater
numbers than all other twin turboprops put together, but I'd sure
like to fly it with a panel designed in maybe the 1980s or 1990s.
J. Mac McClellan was an editor of Flying magazine from 1976
to 2010. He has 12,000 hours and has flown virtually every GA
and business aviation airplane in production during those years.
His semi-retirement job is flying a Beechcraft King Air 350i for a
company based in Michigan.
AOPA Turbine Pilot Magazine - July 2022

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