Avionics News September 2019 - 21

Moving into turbine aircraft increases the likelihood
The natural reaction, as instrument pilots are trained,
that the aircraft's electrical system boasts a higher level
is to identify the nearest suitable airport, communicate
of redundancy - with some standby capabilities.
with air traffic control, and try to remain calm for the
These arrangements worked well for simple aircraft
task ahead: Getting on the ground, safe and sound, with
running analog flight instruments and gauges. The
the aircraft ready to fly again after fixing the electricalbattery could provide power enough to keep a radio,
system failure.
navigator and transponder operating while the pilot
While haste is seldom a wise approach to anything
sought an expedited landing.
in aviation, in an electrical-system
But the steady, seemingly
failure, time is critical - and limited.
unstoppable shift to digital
Similar to an aircraft's fuel
flight instrument technology and
supply, the power available from the
HE STEADY, SEEMINGLY
display-screen instrumentation
main-ship battery is finite - and in
UNSTOPPABLE SHIFT
raises the stakes on electricalmost aircraft, it's the only electrical
TO
DIGITAL
FLIGHT
system reliability - and imposes
power remaining to keep avionics
INSTRUMENT TECHNOLOGY
the need for redundancy in alland illumination going when the
AND DISPLAY-SCREEN
glass aircraft.
generating source fails or something
INSTRUMENTATION
This month, we examine the
disconnects it from the electrical
RAISES
THE
STAKES
ON
issue, the stakes, and the options
system.
for adding redundancy to generalBut it doesn't have to be this way.
ELECTRICAL-SYSTEM
aviation aircraft.
Operators interested in giving
RELIABILITY-
themselves as much of an edge
The stakes change with
as possible face many options for
the variables: Day versus
adding standby electrical power
night and VMC versus IMC
with the addition of a backup battery
Every pilot understands that
to their electrical system.
stakes exist from an electricalsystem failure, stakes which vary
What's at stake?
according to several factors.
For pilots flying behind the old
An electrical-system failure in
standard analog instrument panel,
the pattern poses little threat to
the loss of electrical-generating
the aircraft and its occupants. The
power starts the clock on an
engine continues to run, the airplane remains aloft, and
eventual loss of several critical systems as the battery
the safety of the runway awaits.
drains flat.
The stakes rise significantly if the electrics fail at
For the pilot flying behind a digital panel, with
night or in IMC. But the close proximity to the airport
displays instead of analog instruments, the loss of
keeps the stakes - and the stress - manageable.
electrical power puts at risk the operation of the entire
Venture out on a cross-country flight and the stress
panel.
factors rise along with the stakes. Make the position
With the split-power sources used in so-called steam
miles from the nearest airport, at night in IMC, and
gauge panels, the pilot need not worry about the loss of two
expect a maximum adrenaline surge.
instruments crucial to instrument flying: The attitude indicator,
Now make the weather more than mere clouds - for
or AI - often colloquially called an artificial horizon - and the
example, convective weather, lightning and thunder and
directional gyro, often dubbed the gyro compass.
turbulence, oh my!
Now the pilot faces deeper problems.
Continued on following page

AND IMPOSES
THE NEED FOR
REDUNDANCY
IN ALL-GLASS
AIRCRAFT.

avionics news

september

2019

Avionics News September 2019

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