Page 7.26 IFR Emergencies
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IFR Vacuum Failure; …IFR
Emergency Descent; …Instructional
Opinion; …Emergency Use of
Turn Coordinator; …Cockpit Weather
IFR
Vacuum Failure
The Cessna 182S POH (actually all the new Cessna manuals
say pretty much the same thing) also covers emergency operation
in clouds where a total vacuum system failure is suspected and
"the pilot is not completely proficient in instrument flying.
Executing a 180 degree turn in clouds: "Upon inadvertently
entering the clouds, an immediate plan should be made to turn
back as follows:
1. Note the compass heading.
2. Using the clock, initiate a standard rate left turn, holding
the turn coordinator symbolic airplane wing opposite the lower
left index mark for 60 seconds. Then roll back to level flight
by leveling the miniature airplane.
3. Check accuracy of the turn by observing the compass heading
which should be the reciprocal of the original heading.
4. If necessary, adjust heading primarily with skidding motions
rather than rolling motions so that the compass will read more
accurately.
5. Maintain altitude and airspeed by cautious application of
elevator control. Avoid over controlling by keeping the hands
off the control wheel as much as possible and steering only with
rudder."
IFR
Emergency Descent
The procedures for an emergency descent through clouds are similar,
using power to set up a 500 to 800 ft/min rate of descent, trim
for 80 KIAS and keeping the hands off the control wheel, steering
only with the rudder, using the compass for maintaining heading
rather than the gyro. Recovery from a spiral dive into the clouds
involves retarding the throttle to idle, using rudder and aileron
to level the wings of the artificial plane on the TC, cautiously
reducing airspeed to 80 KIAS, then keeping hands off the control
wheel and steering using only rudder. Clear the engine occasionally,
but avoid using enough power to disturb your trimmed glide. On
breaking out of the clouds, resume normal flight. For these two
procedures Cessna recommends maintaining a heading of W or E
in order to minimize compass error.
Instructional
Opinion
Because the procedure uses a turn and slip indicator instead
of a turn coordinator and recommends only a
3/4 needle deflection, using a clock to time the turn is not
practical. I would make sure the wings are level on the turn
indicator and check the compass heading as the first step in
this procedure rather than guessing what the reciprocal of my
original heading was before I started changing pitch and power
settings.
The idea of keeping the hands off the control yoke from the
very beginning is to keep the pilot from over controlling the
plane. Note that Cessna only recommends that you use the yoke
to level the wings or start a standard rate turn, which should
be easy enough for anyone. The difference is that Cessna recommends
making your 180 with a standard rate turn using a turn coordinator,
while the other recommendation is using 3/4 needle deflection
on the T&S. After that it is hands off the controls. Not
only does keeping the hands off the controls keep you from over
controlling roll, but it also keeps you from messing with the
carefully trimmed pitch that you set up for these emergencies.
The compass and turn indicators are used because the vacuum system
may have failed and because the turn indicator is actually simpler
to use in this situation. The rudder is also used because it
induces less compass error. The procedure also emphasizes slowing
the airplane down, a good idea. Using high RPM propeller will
also give you faster power response if you should break out of
the clouds and suddenly find yourself heading for an obstruction.
Student pilots should practice all these emergency procedures
under the hood with an instructor. The instructor can cover the
vacuum instruments to help the student concentrate on the turn
coordinator and the compass.
Cecil E. Chapman"
Emergency
Use of Turn Coordinator
--Best to do considerable "rudder only' flying
--Center the turn needle with the rudder and keep it centered
using only rudder
--Hands off the flight controls.
--Lower the landing gear.
--Reduce the power above a high idle.
--Trim to its predetermined airspeed.
--Propeller pitch full forward
--Power to the predetermined setting.
--Expect airspeed oscillations
--Check the compass heading.
-- Turn with the rudder.
--Roll out on the desired heading using lead or lag if relying
on a magnetic compass
--Altitude is changed using power supplemented by rudder pressure
to maintain heading
Cockpit Weather
We display on an iPAQ 4700 PDA, using AnyWhereMap software with XM
weather.
AnywhereMap (control vision) has a $2200 PDA system for which you can get TAF,
METAR, and NEXRAD for $30/mo from XM radio.
Yes, as of version 3.0 of Jeppview/FlightDeck you get moving map (vector
based/geo-referenced) en route charts. Likewise for pretty much every approach
plate. The only procedures it will not depict you flying over are the ones
that where route lengths are butchered to fit all on one page (many SIDs/STARs
are like this).
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