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UNUSUAL ATTITUDE RECOVERY
TOPIC: Reacting Quickly in an Over-Banked
Situation
List of OTHER Training Articles
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Written by: Karl "Schlimmer" Schlimm
APS
Emergency Maneuver Training
CFI, ATP - Multi IFR, IAC, ICAS
FAA - Aviation Safety Counselor
Former USAF F-16 Fighter Pilot &
Instructor |
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Karl Schlimm
APS Emergency Maneuver Training
Sept. 09, 2002 07:05:10
Loss
of control of your aircraft while in flight is a
really big deal and occurs more often than is
generally realized. According to
Aviation Week & Space Technology AW&ST
(August 26, 2002, Taming Loss of Control:
Solutions are Elusive), Loss of Control in
Flight (LCIF) is the second highest cause of
Worldwide Airline fatalities. (See Figure 1.)
Figure 1.
World Airline Fatalities
Loss
of Control in Flight usually follows an aircraft
upset or unusual attitude caused by factors such
as pilot distraction, wake turbulence, wind
shear, icing, mechanical failure, etc.
Unfortunately, when it happens, a pilot who has
not been properly trained is usually ill
prepared to cope effectively with such an event.
An ALPA spokesman provided AW&ST with the
following working definition of loss of control
in flight: "if you can no longer get the wings
level, or don't get the wings level." The
airlines generally regard an aircraft upset
condition as "more than 45 degrees of bank, 25
degrees nose up, or 10 degrees nose down". These
are reasonable parameters, given the maneuvering
limitations of an airliner.
But when
would you consider yourself in an
unusual attitude?
Perhaps your answer depends partly on your own
comfort level. What is an excessive bank or
pitch angle in your aircraft? The FAA
necessitates the use of a parachute if bank
angles of more than 60 degrees and/or pitch
angles of more than 30 degrees nose up or nose
down are exceeded. You may be fairly comfortable
with a 60-degree bank angle having practiced
steep turns, but you would probably consider 30
degrees of pitch up or down quite excessive. To
see how prepared you are for an unusual
attitude, consider the following scenario:
Due to
distraction, wake turbulence or some other
cause, you find yourself severely
over-banked, with the nose dropping rapidly.
(See Figure 2.)
Figure 2. Over-bank
beyond 90 degrees
What would you do in this
situation?
To see
what happens to the aircraft in an over-banked
scenario, let's briefly address level
un-accelerated flight. As you learn in basic
flight training, lift must equal the weight of
the aircraft plus any tail down force. (Let's
assume for simplicity that it roughly equals the
weight of the aircraft). Lift is a vector with a
magnitude that approximately equals the weight
of the aircraft in this level flight situation
with an orientation perpendicular to the
relative wind - vertically up in this particular
case. (Picture the lift vector aligned with your
spine, going through your head and out the top
of the cabin or canopy). As you turn, the total
lift vector becomes oriented off the vertical,
and you must increase that total lift so that
the vertical component of lift equals the
aircraft's weight. (See Figure 3.)
Figure 3.
Steep Turn
In a
60 degree banked turn, the total lift must be
twice the weight of the aircraft (hence a "2G"
turn). At 70 degrees (merely 10 degrees of
"over-bank" beyond 60 degrees) our lift would
have to be 3 times the weight of the aircraft.
Any lift deficit here will begin a downhill
spiral journey called a Spiral Dive. When faced
with an over-banked situation, pilots untrained
in unusual attitude recoveries will most likely
panic and pull back on the yoke. As an
instructor, I see this many times early in
APS's Emergency Maneuver Training Program
training despite a thorough briefing (which
drives home the point that the proper response
must be learned by doing - merely knowing the
procedure is not enough). This inappropriate
pilot response is typical because in general,
pilots spend most of their flying time upright
and at bank angles less than about 30 degrees.
Assuming you maintain sufficient flying
airspeed, pulling back on the yoke in these
conservative flight regimes does make the
"houses get smaller." But when over-banked, this
doesn't always work.
At
bank angles approaching 90 degrees of bank, no
amount of pull will produce sufficient lift in
the vertical to keep the aircraft from spiraling
downward. In fact, pulling back on the yoke has
the following adverse effects: 1) induced
drag increases with increased lift; 2)
pulling will tend to tighten the spiral dive;
3) pulling too hard at airspeeds above
maneuvering speed could result in structural
failure of the aircraft; 4) pulling above
the "aerodynamic limit" at airspeeds below
maneuvering speed will result in an accelerated
stall; 5) at bank angles over 90 degrees,
any lift on the wings will literally pull the
nose to the ground (see figure 2).
Another important point to consider is that
aircraft trim may work against you, especially
in this scenario. While the airspeed begins to
increase in your downhill flight path, the nose
will trend downward progressively more rapidly
(just as it begins to rise in level upright
flight as you increase airspeed beyond the
trimmed airspeed). If you are lucky enough not
to over-stress the aircraft, and have sufficient
altitude to recover, then there is no harm done.
But this is all too often not the case.
So what is the proper
recovery from an over-banked aircraft attitude?
In the
APS - Emergency Maneuver Training Program,
we teach the following response: "Power
- Push - Roll" based on techniques and
procedures detailed by Rich Stowell, NAFI
Master CFI - Aerobatic, Author:
Emergency Maneuver Training: Controlling Your
Airplane During a Crisis.
Again referencing the August 26, 2002 issue of
AW&ST ("Delta Upset Training Founded on
Simplicity"), Delta uses a similar recovery
technique for upset recoveries, which is:
"pitch/roll/thrust check, level" which means
"adjust pitch, [roll] rate, thrust settings and
level the aircraft."
Let's analyze the 3
elements of the "Power, Push, Roll" sequence:
POWER: If the airspeed is decreasing,
as in a nose high unusual attitude, then the
answer is fairly obvious - push the power up to
preserve airspeed! But in a nose low unusual
attitude, the answer is not always obvious. In a
case such as a graveyard spiral where airspeed
is increasing rapidly toward Vne, then the power
should be reduced to idle…
But what about a wake
turbulence encounter on final approach?
If
we are faced with an over-banked attitude on
final approach, we are low and most likely
fairly close to the 1G stall speed, at least
initially anyway. In this case, increase
power for the following reasons: 1)
power will assist you in avoiding settling
to the ground; 2) increasing airspeed
above the 1G stall speed, and towards
maneuvering speed, will increase control
effectiveness (making ailerons more
effective in rolling the aircraft upright,
for instance) and once upright, will allow
you to recover from the resulting nose low
attitude with minimum altitude loss. You can
minimize your turn radius (and thus maximize
your distance from the ground) in the
resulting dive recovery by pulling to the
maximum lift capability of the wings (just
below the stall buffet or other stall
warning) at speeds at or below maneuvering
speed (Va). Above maneuvering speed, turn
radius will increase dramatically. As a rule
of thumb, then, increase power if airspeed
is initially below maneuvering speed and not
trending rapidly toward it or about to
exceed it. If already above maneuvering
speed or rapidly accelerating towards it,
then decrease power.
PUSH:
This means, "unload" the aircraft. If you were
pulling back on the yoke, now is the time to
stop! It does not mean an aggressive negative-G
push to keep the nose up. The idea is merely to
decrease or possibly halt the nose's trend
downward while the aircraft is being rolled
upright. (This is certainly a good excuse for
always being firmly strapped to your seat!) Even
a modest push will necessitate a definite
forward pressure on the yoke. You will be
fighting the aircraft elevator trim! During the
roll upright, smoothly move the yoke back to an
aft of neutral position (assuming you had pushed
while over-banked). Otherwise you will wind up
pushing the nose down once upright. (This is
sometimes difficult to conceptualize without
training).
ROLL:
Rolling upright (thus orienting the lift vector
vertically upward) is a priority in this nose
low over-banked unusual attitude. The faster we
can re-orient the lift in the vertical, the
sooner we can recover from the nose low unusual
attitude. Which way do we roll? It is
usually best to roll in the shortest direction
to the horizon. In the case of wake turbulence,
if the aircraft is still rolling in the grip of
the previous aircrafts wingtip vortex or if the
roll cannot be arrested early, it is probably
prudent to continue the roll in the direction of
vortex. Regardless, rolling will result in less
altitude lost than pulling. (This is true unless
in a near vertical descent) Repetitive exercises
are essential to instill the proper rolling
response versus an inappropriate pulling
response. It is important to roll using rudder
in the direction of roll. As the aircraft is
rolled upright, rudder is essential for the
following reasons: 1) it "coordinates"
the roll, eliminating adverse yaw, which would
otherwise drive the nose downward; 2) it
quickens the roll (yaw induced by application of
rudder induces a secondary roll response); 3)
when rudder is applied at bank angles in the
vicinity of 90 degrees, it acts somewhat like
the elevator does at small bank angles, serving
to "hold" the nose up for the short time
(hopefully) that the aircraft is at bank angles
closer to 90 degrees. How much rudder do you
use? Use at least as much as you normally
would to coordinate the roll. Too much rudder,
however, especially at higher airspeeds, can put
severe stress on the empennage, and aft section
of the fuselage.
Once
you have rolled upright (lift vector in the
vertical), you must now recover from the
resulting dive. Why wait until upright before
beginning the dive recovery? Because
simultaneous application of aileron and elevator
results in "asymmetric" loading or "G's" and can
produce very high local stresses at the root of
the wing with downward deflected aileron (the
upward moving wing). If a "push" was initiated
while inverted, then the yoke may be returned to
it's normal aft-of-neutral position in the roll
upright, but it's best to orient the lift vector
in the vertical before pulling towards the limit
G load of the aircraft in the dive recovery.
To summarize the recovery
procedures for an over-banked unusual attitude:
POWER: decrease, if nose low and above
maneuvering speed; Increase, if nose high or
nose low and below maneuvering speed. PUSH:
to reduce G- loading, and if over-banked, to
slow or stop the nose-down pitch. ROLL:
use rudder in the direction of roll. RECOVER
FROM THE DIVE.
So what is your best defense
in aircraft unusual attitude or upset
conditions?
-
First, attempt to
avoid conditions that can induce unusual
attitudes
in the first place! Steer clear of
thunderstorms and wake turbulence! Avoid
IMC or flight into low visibility
conditions if not properly certificated
and trained. Avoid distractions.
-
Second,
get the proper training.
According to an article in AW&ST (May 8,
1995 issue): "Training should include
flights in aerobatic aircraft to
practice recovery techniques because no
simulator can model the disorientation
of actually being upside down...
recurrent training every two years, with
time in an actual aircraft, would be a
good start." Regardless of the aircraft
that you fly, proper training will
enable you to learn to react decisively
in a high-pressure environment, and to
learn proper recovery techniques to
avoid a "panic" response that could
worsen the situation.
- Contact
a APS - Emergency Maneuver Training
representative. Certainly, we would like
to take this opportunity to recommend our
program at APS which offers
three course layouts to choose from.
Please give us a call a 1-866-FLY-HARD and
ask to speak with a flight training
specialist or submit this
online form for more information today!
If you are attending the NBAA Convention
this week in Orlando 10-12 Sep 02,
representatives of the APS - Emergency
Maneuver Training Program will be at
Booth #1604. It would be our pleasure to
speak with you about our training
program and how APS can customized its
services to meet your specific needs.
Get this training
somewhere. The life you save may be more than
just your own.
Join the APS Training Newsletter
"The Aviation Performance Solutions
(APS) Emergency Maneuver Training
program is far more comprehensive
than the majority of 'other' courses
offered out there. In my opinion,
the equipment used by APS and the
experience level of its instructors
are especially well-suited to the
corporate and airline training
market."
Rich Stowell - NAFI Master CFI -
Aerobatic
Author: Emergency Maneuver
Training:
Controlling Your Airplane
During a Crisis |
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