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Know Your Airplane
Every pilot should know the instrument power sources for each airplane flown, and
particularly know the consequences of loss of any source of power, air or electrical,
or loss of any instrument, and be prepared to cope with the loss.
Know Yourself
Airplanes can be flown safely with loss of one or more gyroscopic instruments.
Every instrument rated pilot demonstrated the ability to do so prior to receiving
the rating. The problem is that many never practice the skill and only a few have
ever practiced in turbulence, as it seems an unlikely need in routine operations.
Professional pilots who are required to take semiannual simulator training practice
a lifetime of emergencies each training session although they rarely encounter
emergencies in daily operations. Most general aviation pilots remain "current"
by flying in the system and may rarely face or practice emergency situations. For
most pilots, continued flight in IFR conditions with failed gyro heading and attitude
instruments is a high work load situation that could lead to a fatality.
If You Are Not Instrument Rated
If you are not instrument rated and inadvertently encounter instrument weather,
the 180 degree turn is usually the best course of action. If your pneumatic driven
gyro instruments fail, it is still possible to make a 180 degree turn by using the turn
and bank (or turn coordinator), magnetic compass and clock. Likewise, a descent through
clouds to VFR conditions can be made using the turn indicating instrument. These
procedures may be tailored to each airplane type and model and should be demonstrated
by and practiced with an instructor. It may be too late to learn them when faced with
actual need. Avoid conditions that risk encountering instrument weather.
If You Are Instrument Rated
If you are instrument rated and gyro instruments fail or mislead, do not be afraid to
ask for help. ATC personnel know where to find better weather and are able to give
"no gyro" heading directions. The whole system - radar, weather reports,
communication, and personnel - is instantly available to assist you.
Do not try to be a "hero" and continue on bravely as if loss of pneumatic power
is no big deal. It can be a serious emergency unless you have maintained high proficiency
in partial panel flying.
Also, cover the dead or lying instruments. Most partial panel practice is done with
covered instruments, but in real cases the artificial horizon will be sagging and
giving erroneous information that your instincts want to accept as correct.
Autopilots that use these instruments as sensors must be turned off immediately.
Note: Again, you need to know your aircraft systems thoroughly, so that you will know how
a pneumatic system failure affects other equipment.
Finally, if your airplane has no back-up capability, be very cautious in the type of
IFR you fly. Solid IFR from takeoff to touchdown can be very difficult on
partial panel.
Back Up - Better Way
If your airplane does not have a back-up, or stand-by system, and if you use your
airplane for IFR flight, consider a back-up or stand-by pneumatic system. Several
manufacturers offer a variety of alternate systems that will supply vacuum or pressure
if the engine driven pump fails. While the chances of pneumatic system - or pneumatic
driven instrument - failure while in actual IFR conditions has been demonstrated to
be small, those same statistics also demonstrate that the cost of a stand-by system is
far less than the too often fatal results of not having a back-up.
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