Contents
Recommendation; ...Categories
of Aircraft; ...Definitions; ...History
of Spins; ...The Airplanes; ...Spin
Training; Teaching of Spins; ….Spin
Accidents; ...Preliminary Instruction; ...Spin
Causes; ...Stages of the Spin; ...Spins
in Brief; ...Spin Structure; ...Unintentional
Spin Entry Situations; ....Avoiding
the Base to Final Spin;
....Things to Know about
Spins; …Spins out of a Skid; ...Spin
from Downwind Turn Entry; …Spins out of
Slips; ...Spin Entry; ...Recovery;
…Spin Rebuttal: ...Spin Types;
...The
Unrecoverable/uncontrollable Spin; ...Other Recoveries;...Generic
Spin Recovery; ...If
You don't Use Procedures Recommended; ...Historic Spin
Requirements; ...Current Spin
Requirements; ...Endorsements (Instructor); ...Spin
References; ...Spins Revisited; ...Yaw
Required to Spin; ....Spin
Statistics; ...The Facts; ...1987
Statistics; ....Expert Opinion; ...AOPA
Study; ...The New AOPA Study; ...General
Aviation Pilot Stall Awareness Training Study; ...Spin-Statistics;
....Flying
with Instructors Can Be Dangerous; ...Instructional
Background; ...NTSB
Aerobatics Accidents; ...NTSB's Analysis;
...Stowell’s Hypothesis; ... POH Stall Altitude Losses; ...Real-life
Conditions; ...Stall vs Spin; ...Protecting
Yourself from Stall/Spin Accidents; ...Required
Knowledge about Stalls and Spins; ...Knowing
Stalls; ...Knowing Spins; ...Stepping
on the Sky; In Charge of
the Spin; ...A Spin Virgin No More;
...
Recommendation:
Every pilot should plan to finance at least five hours or even ten hours of
aerobatic flight instruction. This should be from a full-time aerobatics
instructor. Flying upside-down will make you a better right-side-up pilot. It is
here that you learn to apply forward pressure when inverted to go up.
You have read that an airplane can be stalled from any attitude and at any speed. Doing aerobatics gives you an opportunity to turn the theory into practice. Spin training can be taught safely if the altitudes and maneuvers are planned for safety. Those against spin training desire that stall prevention and recognition are the way to go.
Categories of Aircraft
Normal Category
Normal category aircraft are placarded against spins but they are factory/FAA
tested to one turn (or three seconds) with a one-turn recovery when controls are
used correctly. Speeds and load factors are not to be exceeded. Flaps may be
retracted. No uncontrollable spins are possible in this category. No acrobatics
or spins allowed. The weight and CG certification of the aircraft will determine
its spin characteristics and recovery procedures. Beyond one turn even correct
control input may not work.
Acrobatic Category
Recovery at any time in one turn Tested to six (6) turns clean and one (1) turn
w/flaps Speeds and load factors not to be exceeded. Uncontrollable spins are not
possible. Entry speeds listed for all maneuvers. The weight and CG certification
of the aircraft will determine its spin ability and recovery ability.
Utility Category
Meets either of above requirements FAR Section 23.1567 (New types of airplanes)
Pilot to assume aircraft placarded against spins may become uncontrollable in a
spin. The weight and CG certification of the aircraft will determine its spin
and recovery procedures.
Limited aerobatic maneuvers may be conducted in aircraft that are not certified in the aerobatic category. Some normal category aircraft when operated within the utility category of their weight and balance envelope are permitted to perform those maneuvers listed in placards or the POH.
Definitions:
SPIN An established spin is an aggravated stall that has developed
auto-rotational forces. Gravity causes a helical path during the descent. The
aerodynamic and inertial forces are balanced. You must upset this balance to
recover. The stall, which has directional control, occurs at an angle of attack
near 17 degrees. In a spin the down wing may have an angle of attack of 70-80
degrees while the up wing will be between 30 and 40 degrees. The stall prelude
to the spin lacks directional control (rudder).
TAIL LENGTH This is the distance from the Center of gravity to the hinges of the
tail surfaces. The longer the distance the more nose down the spin and the
easier the recovery. An improperly loaded aircraft with a short tail length will
spin flat and can be unrecoverable.
STALL Loss of lift and increase in drag that occurs when at angle of attack
greater than angle of maximum lift.
SECONDARY STALL Stall that occurs if recovery from initial stall is
inappropriately performed usually by excessive elevator.
STALL SPEED Speed at which the critical angle of the relative wind is exceeded.
Stall speed decreases with aircraft weight, turbulence, bank angle, abrupt
control movement, or any interference with airflow over the lifting surfaces
(ice)
ANGLE OF ATTACK Angle the wing chord line has when it meets the relative wind.
CRITICAL ANGLE OF ATTACK Will always result in a stall. The flow of air cannot
follow the curve of the wing. For a given flying surface the critical angle of
attack never changes. The airspeed at which a flying surface will stall depends
on aircraft weight, balance, and load factor.
RELATIVE WIND Speed and direction of wind causes by the aircraft movement.
Velocity of relative wind is equal but opposite to speed of aircraft.
COEFFICIENT OF LIFT, (Cl) Factor giving lift created by an angle of attack at a
given airspeed.
COEFFICIENT OF DRAG, (Cd) Factor giving drag created by a an angle of attack at
a given airspeed.
FLAPS Flaps are lift/drag devices that lower the stall speed. The lift effect is
greater than the drag. Flaps make the glide slope more steep for better aim to
the landing site. Vso stall speed in the landing configuration.
Vsi Stall speed in a specific configuration.
Va Maneuvering speed at which the airplane will not fold, crumble or mutilate if
stalled. No guarantee if stalled above Va.
LOAD FACTOR Is ratio of available lift to total weight. Load factors can be
increased by steep turns, abrupt control movement, and turbulence. In level
flight the load factor is one. In a 30° bank the factor becomes 1.15, at
45° bank it becomes 1.40, at 60° bank it becomes 2.00, at
70° bank it becomes 3.00, and at 80° bank it becomes 6.00.
CENTER OF GRAVITY CG has indirect effect on angle of attack and the control
forces required on the elevators. The CG does affect the aircraft stability and
spin recovery. With an aft CG very light control forces could cause a stall from
which the available elevator power could not lower the nose for recovery.
WEIGHT The greater the weight the higher the stall speed. The AFM/POH give
approach speeds based on allowable gross. At less than gross weights lower
approach speeds are allowable. For intentional spins the actual weights must be
computed. A rule of thumb is that a 2% increase in weight will cause a 1% change
in stall speed.
DENSITY ALTITUDE High altitude and temperature give higher true airspeeds. Since
stalls occur at indicated speeds as per the AFM/POH density altitude is not a
factor.
TURBULENCE At approach speeds turbulence may cause stalls by changing angle of
attack. At cruise fly above stall but less than maneuvering speed.
TRIM Trim is the pilot's pitch management tool which decreases the effect of distractions.
History of Spins
Parke
A test pilot, Wilfred Parke, was in a Roe Avro while making a spiraling descent.
He inadvertently entered a spin when he failed to remove bank while applying
backpressure. Parke made several power and control changes without effect. Parke
finally applied and held opposite rudder. The aircraft recovered from the spin
and entered a dive. An aviation first.
A few months later he was killed, after engine failure, while turning back to
the runway. Apparently, knowing how to recover from a spin is of no avail if you
are not aware of the conditions and initiating factors for spins.
Without altitude a recovery in time may not be possible.
Lindemann
SPINS WERE A ONE TIME THING IN 1914
An unheralded aviation pioneer is British scientist, F. A. Lindemann.
"The Prof", as he was known, led a very checkered scientific and
social career from early WWI through WWII. He was an "idea man" and
advisor to Churchill for thirty years. He was a social butterfly and a
scientific gadfly to more capable scientists. However, his place in history
could well lie in aviation. You never heard of him?
Born of German/American parents, he spoke heavily accented mumbled English. He
knew all the "right" British nobility and used their influence to
gain both position and prestige. In 1914 he attempted, but failed because of
eyesight, to join the Royal Flying Corps. He then used influence to join the
scientific staff of the Royal Aircraft Factory.
Lindemann initiated a study of the instrument readings and pilot procedures
that seemed to cause the stall/spins occurring during turns. A letter to his
father stated, "Nobody can make out quite what happened." Lindemann
could find no apparent pattern as to when a stall or a resulting spin might
occur. Once an aircraft was in a spin there was no way out of it. The spin
turns would increase in speed until the ultimate crash. All flight instructors
warned, "Get into a spin; get killed".
The "spin" was the most dreaded unintentional flight occurrence,
which resulted in accidents. More to be feared than the more frequent landing
accidents. At least, landing accidents could be explained. Lindemann now had
an explanation, a theory, about spins.
While never publishing his study results, Lindemann gave many oral accounts of
his findings. The spin frequently occurred when the aircraft stalled in other
than an absolutely level condition. If one wing dropped any effort to raise it
would cause the other wing to flip over the other direction uncontrollably.
Even at high speeds, a tight turn might cause one wing to flip over and cause
a spin. He insisted that further study to prove the theory required that
scientists fly.
Without any flight skills, Lindemann had worked out in theory the probable
forces, which caused and existed in a spin. He also figured out, in theory,
the control movements required to counteract these forces. His study showed
that any instinctive response would not work. The rudder must be held fully
against the spin while the nose was kept pointed toward the ground. You could
not pull back on the stick until the spin stopped and flying speed was gained.
His theory also seemed to indicate that during the recovery the wings of the
plane could be pulled off. The way Lindemann used to test his theories was
somewhat akin to a medical researcher doing a self-inoculation for a deadly
disease. He worked through and around the bureaucracy, used influence,
memorized the eye chart for his "blind" eye and learned to fly
"poorly". One flight of uncertain date in 1914 justifies Lindemann's
place in history.
On this Fall day, he discussed his theories on spin recovery and the planned
experiment with selected observers at Farnborough aerodrome. He told them he
would deliberately do a stall spin. He certainly must have said his good-byes.
He would be using a B.E.2 aircraft of most uncertain flight characteristics.
He departed and climbed for many minutes. Far below, the observers saw him
reach what must have been the B.E 2's service ceiling of 14,000 feet. They saw
the spin well before they heard the cessation of engine noise.
Lindemann now began to test his theory. He pulled the power, slowed the plane
and entered into a stall. He held the stall until the left wing dipped and the
right wing flipped up for the spin entry. A deliberate entry into a maneuver
from which no one had previously recovered and few had survived. A maximum
test of accountability and courage.
The fragile airframe was held together by a maze of wires and struts that
maximized a power off vertical speed of about 90 mph. Lindemann held the spin,
intentionally or otherwise, until it was fully established and then he
initiated his unique recovery. A planned application of control forces never
before applied. He put in full opposite rudder. Nothing happened. He waited.
Still nothing happened. He applied forward control pressure.
He had already fallen thousands of feet with no control effect discernible.
Was his theory going to fail at this critical moment? But the rudder was
starting to have an effect. The spin was slowing and finally stopped. From the
vertical, but without the spin Lindemann now had to complete a recovery.
Survival demanded that the pull out would not remove the wings from the
fuselage. Slowly, carefully the nose rose and as it rose the aircraft slowed
thus easing the stress on its components. The first intentional spin and
recovery. All that and survival. Enough?
One such experiment and proof would have satisfied most people, but not
Lindemann. He climbed back up to altitude and did the spin and recovery in the
other direction. A theory twice applied and proven to be a life saver. From
that day on, a pilot's education has not been deemed complete without spin
training. (Except, of course, in the U.S. by the FAA)
The British had a military secret. It combined two of the very best qualities
of military combat. Deception and skill'. Imagine their chagrin when the
British plane would level out close to the ground and scoot to safety. Indeed,
the spin was often used in WWI as a deliberate escape maneuver. It wasn't long
before the Germans discovered the deception and began to follow spinning
planes all the way to the ground. It is not known how the Germans gained the
secret of spin recovery. Pilots like to talk flying with other pilots.
Most great aircraft flights recorded in aviation history are about distances,
speeds and kills. Why not a special "save" category for Lineman along with Immelman? But again, wouldn't your entering his name into your
memory and applying his theory and practice to your own "Lindemann"
spin recovery be sufficient.
The Airplanes
Normal category aircraft that are placarded against spins must be considered
as being non-recoverable from spins. Certification today does not include
ability to recover from a fully developed stabilized spin. The required one turn
recovery is only the incipient stage of the spin. Aerobatic aircraft have not
been tested beyond six turns.
There are legitimate concerns as to just how effective having an aircraft
placarded against spins will be in preventing distraction caused spins. Aircraft
design, pilot knowledge, enforced training standards, and pilot proficiency are
historic causes and corrective factors.
The design of an aircraft rudder section that remains clear of the shielded air
that occurs over the horizontal stabilizer and elevator makes for positive spin
recoveries. If the empennage extends below the tail if gives a preferred nose
down spin. The intent of the T-tail was to provide this desirable clearance but
it sacrificed pre-stall buffet. Horizontal stabilizer fillets and a long dorsal
fin improve recovery characteristics. One two-place trainer may not recover if
loaded over over-maximum gross weight.
Some four-place aircraft rotate so rapidly that the rudder cannot stop it.
Requires a parachute. Other aircraft the recovery is too quick when the ailerons
are turned into the yaw direction. The resulting secondary stall precipitates a
spin in the other direction. The full, abrupt forward elevator control can
create an inverted flat spin. There is no place where a pilot can find the names
of the aircraft involved.
The normal category of aircraft is certified for a one-turn spin followed by normal recovery. One turn is still in the incipient phase with weak rotational forces and un-stabilized condition. Spinning an aircraft placarded against spins means the pilot is aware that any spin may be uncontrollable and unrecoverable. There are those who would blame the stall/spin accident prior to 1949 on aircraft design. There are those who would say the problem is lack of training, since in that 1949 period solo in less than ten hours was very common.
Spin Training
The Department of Commerce in 1926 had airworthiness requirements for an
aircraft to be recoverable from a spin. Ten years later the manufacturers were
expected to include standard procedures for spin recovery. To obtain a private
or commercial license an applicant was expected to be proficient in precision
spin recoveries. About 1950 the government made a major change by requiring
stall awareness instead of spin recovery. Flight instruction was required to
include power-on/off stall recoveries from normal flight conditions.
Since a spin cannot occur without its initiating stall, it was thought that
recognition and recovery along with manufacturing improvements would lower the
stall/spin accident rate. Spins were required only from flight instructor
applicants. In the late '80s the accelerated stall was removed as a test
requirement. In the mid-nineties full stalls have been eliminated. Stall
recognition is now the prime requirement.
The government, not recognizing that the average age of an aircraft is now over
twenty-nine years, has presumed that improved airworthiness requirements for
spin resistance has eliminated all stall requirements beyond recognition of the
stall and situations leading to the stall. Any pilot who learns to fly in a Part
23 certified aircraft is likely to become a statistic if caught flying an
aircraft certified prior to Part 23 certification.
The essence of spin instruction is not entering the spin or even to make a
recovery. It is that you become aware of those situations and conditions that
are conducive to the initiation of spins. Avoidance is the key. The untrained
pilot will always try to recover with incorrect control input.
Fatalities are not from intentional spins, but from those where an accidental
stall leads to a spin. Safety is a matter of choice. As a pilot you have a
choice in the avoidance of controllable risk factors. The more competent pilot
is more likely to choose a path of lower risk.
Teaching Spins
The student must first become acquainted with full power-off stalls
maintained with yoke all the way back and up while rudder is used to pick-up any
wing drop. Rudder turns may be practiced. Next the power-on stalls much the same
way but rudder applications must be more in anticipation of any drop. Should a
break occur, let the wing get well down before initiating the recovery from the
incipient spin.
When you are ready for the spin just continue to hold the yoke back during the 'break'. If you relax during the break you may enter a spiral. Always get the power off and the flaps up when in a spin.
Spin Accidents
It is most likely that any decrease in the stall/spin accident rate has
nothing to do with whether or not spins are being taught in training. Figures
show that nearly 50% of aircraft accidents were caused by the stall spin. Now
such accidents are a little more than 10% blamed on the stall spin. The
stall/spin accident rate of pre-1949 aircraft remains over 40%. Having an
instructor aboard is not assurance that a stall/spin accident will not occur
even in modern aircraft.
12% of small plane accidents result from spins and comprise 25% of the
fatalities. 20% of spin accidents had an instructor aboard. 95% of the
stall-spin accidents are initiated below pattern altitude. Some aircraft,
training procedures, and decision-making training contribute to these
statistics. Descending turns from downwind to base and base to final are the
most likely encounter points. A relatively high power setting or an increase in
power during these turns will make the aircraft easier to stall/spin because of
the increased airflow over the tail surfaces. In these turns only a small amount
of rudder is required to initiate the spin. Full elevator is not required and
any buffet may not be detected. No recovery with flaps was successful.
The only recovery that has a chance is full reversal of the rudder application.
Any use of the elevator or ailerons will be counter productive. The more flaps
the greater the tail download due to airflow; this causes the aircraft to pitch
up without the usual stall warnings. The sequence of control inputs is first in
importance but this is closely followed by the timing of control input. The
awareness, recognition and prevention of stalls are essential at low altitudes
since the spin is not likely to be recoverable. The initial entry into this
situation is caused by a distraction. The NTSB says that 40% of these accidents
are initiated by a distraction. To get this statistic they must have been
talking to a goodly proportion of dead pilots.
Pattern distractions are of several types. The most likely will be some form of
radio communication. In cockpit distractions come next. The implied or real
presence of other aircraft even if seen peripherally can result in instinctive
control inputs conductive to the stall spin.
The avoidance of distraction requires some emotional and intellectual control.
The pilot workload is heavy. The addition of a distraction can be the final
straw that takes the pilot's mind off the flying of the plane. Out the window go
all the planning and the checklist. The distraction becomes the focus of
attention to the elimination of everything else. This only has to happen long
enough for the initiation of an unrecoverable spin. I have found the best way to
minimize the influence of distraction is to create as many as possible. Actual
or created makes no difference, just expose the trainee to as many as possible.
No amount of training in spin recognition or recovery will be effective for the
low altitude stall spin. Only training in maintaining the angle of attack, bank
angle, and airspeed can be effective. More importantly the training program must
rely on the development of judgment. The best decisions a pilot can make
regarding the pattern size, making the base turn, adjusting the base leg,
turning final just right for runway alignment, making approach adjustments of
flaps, power and airspeed, entering the flare and holding on to the touchdown
are all a matter of good judgment. It's all a matter of judgment training. Do it
right and the presence of a distraction becomes a non-factor. Remove the
distractions and you abolish the stall/spin and the accident.
In the process of building judgment I structure my lessons to expose the student
to adverse situations likely to be encountered. The use of trim, yoke and power
is an art. Every flight situation can be varies by an infinite combination of
each. I try to reduce the options by having the student set as many constants
and use only one variable at a time. I emphasize constant power until the
landing configuration is established. Then power becomes a variable. I want to
minimize the workload by setting constants where possible.
Preliminary Instruction
--No spin without a stall.
--Aggravated stall gives spin.
--Wing with greater angle of attack stalls, drops while nose yaws.
--Descent is helical (like a coiled spring)
--Only in approved aircraft
--Begin with stall practice
--Spin avoidance from stalls and slow flight by making immediate recovery
--Incipient spin recovery with immediate use of rudder and lowering angle of
attack
--Configure for power on/off stalls
--Rudder at stall
Release control pressure, opposite rudder, forward elevator pressure
Spin Causes
Turning with excessive/insufficient rudder
Instrument readings become unreliable
Immediate recovery or enter spin
Skidding turn spin direction goes with controls
Slipping turn spin opposite to aileron
(L-R reading on turn coordinator is best indicator.)
The Stages of the Spin:
1. The stall
2. Conventional
3. Accelerated
4. Inverted flat
Any one of the stages can lead to any of the subsequent levels.
Spins in Brief
Stalls do not cause spins. Once a stall occurs and the pilot misuses rudder,
aileron, or power individually or in combination auto rotation occurs from the
resulting asymmetrical stall and a sideslip.
There is an abrupt loss of control when leaving the stall and entering the spin.
The untrained pilot will always react instinctively and apply controls
incorrectly thus aggravating the spin entry.
An incipient phase occurs when the foregoing stall is accompanied by
uncoordinated yawing. The yaw induces a roll due to increased asymmetric lift on
the wing opposite to the applied rudder. The aerodynamic differences from
uncoordinated stalled flight causes the nose to drop.
In a spin both wings may be stalled but the one on the outside of the spin has a
higher speed and a slightly lower AOA than the inside wing. It is this
difference in the two wings AOA and its companion induced drag that causes the
turning of the aircraft.
The autorotation to follow is quite varied as long as the dynamic and inertial
forces are unbalanced. Airspeed will be changing but the faster the entry the
longer it takes to stabilize the spin. By the second turn we may be in a
developed (stabilized) spin. IAS will be pegged a few miles above 1G stall
speed. Descent will vary but can reach 7500' fpm.
If the center of gravity of the aircraft is aft, with any adverse control
application can lead to an unrecoverable flat spin. The 'blanking' of the
vertical tail surfaces by a low mounted horizontal tail can prevent the
rudder from becoming effective against the spin. Aircraft tend to recover
quickly if the power is off and controls moved to neutral.
Spin Structure
Spins have three phases:
--Incipient
Know how to recognize the beginning of a spin. Quickly apply the proper control
input. Get out of the incipient spin before it has a chance to develop. In a
developed spin an aircraft prohibited for spins may be unrecoverable. To prevent
this from occurring, the recognition and recovery from an incipient spin is a
desirable training goal. The first turn of a spin causes the greatest loss of
altitude, as much as 800' to 1000'. High-density altitude causes faster rate of
spin and greater loss of altitude.
Recovery: Immediately, power off, opposite rudder, forward on yoke always in
this sequence. If rudder is effective yoke forward may not be necessary.
Otherwise, hold full application of controls until recovery. Check turn
coordinator for direction if in doubt. The proper recovery from the incipient
spin must be initiated at once or the yaw rate will become faster and the nose
more toward the vertical.
--Developed
Spins are fully developed after four turns. Spins are low stress maneuvers for
airplanes. When the incipient state stabilizes the dynamic and inertial forces
become balanced. They become both equal and opposite. The turn rate, airspeed
and vertical speed are constant. Some engines quit during spins. The engine of a
C-150 may quit after 8 turns due to unporting of fuel tanks. A 152 takes 12
turns. The size of the rudder determines efficiency of spin recovery. Power
makes the spin faster, flatter and makes recovery take longer.
Recovery: The developed phase of the developed spin has two possible outcomes.
a. The recovery, from which the ensuing dive can pull a wing off. Be gentle.
b. The crunch.
(No recovery is possible of a flat spin with rotation about center of gravity
except by moving C. G. forward.) Undo your harness and get on windshield panel.
Unintentional Spin Entry Situations
Some of the following situations are pilot/instructor created. The pilot who
does not trim for each stabilized flight situation may react to distraction by
misapplication of the controls. The pilot who does not fly the airport pattern
to maintain a size and shape commensurate to wind conditions is creating a
stall/spin situation. The pilot who fails to make flying the aircraft the first
priority is looking for a stall spin accident.
I have often contended that the pilot or instructor who does a high percentage
of his landing practice at one airport is greatly reducing the opportunity to
develop judgment skills in pattern operations. A student needs to rely on a
developed skill and judgment for flying a pattern without reliance on geographic
terrain indicators. I make a practice of having students 'read' the windsock
before getting into the aircraft. The 'read' is always compared to the ATIS or
AWOS. As 'reading' skills improve the student can make 'readings' from the air
so that patterns are sized to wind conditions. Ground 'walk-throughs' clarify
the how, why, when, what, and where for pattern adjustments.
Things to Know about Spins:
--Spin training has not proven effective in preventing or even decreasing
the statistical numbers related to stall/spin accidents.
--Over the years, spins have been responsible for about 12% of the accidents and
one-fourth of the fatalities.
--Only 5% of all stall/spin accident occurrences happen at altitudes where a
recovery would be possible.
--Over 40% of the accidents affecting aircraft certified prior to 1945 are
stall/spin accidents.
--Thousands of unreported recoveries from unanticipated spins occur for every
spin accident.
-- The lowering of the stall/spin accident rate is more due to improved aircraft
design than any regulation or training.
-- 40% of unintentional stall/spin accidents are caused by pilot distraction
when buzzing' at low altitude. Positive full elevator ........forward is your
best chance of recovery.
--The stall/spin accident rate would increase if spin training were required.
--Human error causes 95% of all stall/spin accidents. The untrained pilot will
always apply the controls incorrectly.
--73% of stall/spin accidents result in fatalities.
--Nearly one out of three stall/spin accidents now involve homebuilt aircraft.
--20% of stall/spin accidents result when the pilot perceives a problem and
becomes distracted.
Spin Out of a Skid
The spin from a skid can be entered from a left turn in a shallow bank. Pull
the power and slow as though making a power-off stall. Just before the stall put
in full bottom rudder. This tightens the turn much as might happen in the
downwind base to final turn to a runway. The wing will drop and you should apply
full right aileron. Recovery from the spin is normal.
Avoiding the Base to Final Spin.
--Short and easy out is to level the wings and execute a go-around
--Continue the turn, make a teardrop back to the centerline. Keep a
constant-angle bank and airspeed.
Use power to control your altitude during the turn. ,
--Increase the angle of bank to tighten the turn. Use coordinated controls with
attention to keeping the ball centered for every change in bank. You won’t
spin unless yaw occurs. Release rudder pressure once a bank has been reached.
Increased bank increases stall speed. Lower the nose accordingly regardless of
ground proximity. Being close to the ground is not a problem unless you hit it.
Use power as necessary. Do not attempt to increase your bank angle with rudder
first. If you don’t like a steep turn close to the ground don’t do it.
--The illusion of making the turn quicker with use of rudder is increased by its
ability to lower the nose...Close proximity to the ground will cause the nose
lowering to trigger the instinctive reaction of pulling back on the yoke. This
will not stop the skid but will decrease you airspeed. The angle of attack will
increase and any yaw caused by the rudder creates a spin. Recovery totally
depends on having sufficient altitude.
By picking an imaginary airport at least five thousand feet AGL and pretending to make a downwind base to final turn in the above manner, you will get a spin that will quickly take you below your imaginary ground level.
Spin Out of a Slip
A spin out of a slip is a "spin over the top". You must to force
it into the spin. Enter a steep climbing turn to the left until you stall. Keep
the power on. When the stall breaks and the high wing begins to drop hold the
yoke all the way back and up while putting in full top rudder. Hold the controls
to the stops while the airplane rolls inverted and the nose will drop down into
the spin. Recovery is normal.
Spin Entry:
Teach spins by entry in a stall aggravated by a skid.
At stall, full rudder, full back elevator
At full turn recover never reaching Vne
The smoothest positive spin entry is when rudder is applied just above the
normal stall entry speed. The yoke must be held full back and up. Power can help
avoid a spiral and create a positive spin entry but should be off after entry. A
spin occurs when directional control is lost in a stalled condition. At or near
the stall, the opposite to rudder and aileron rolls and yaws the aircraft into
the spin. Thus we precipitate a spin by purposely doing a stall from
uncoordinated flight.
Skid: Too much rudder and not enough aileron.
Slip: Too much aileron and not enough rudder.
If you have too much right rudder, in a bank to the right that's a skid. Too
little right rudder or any left rudder gives a slip. Generally, any slip will
require opposite stick and rudder.
A spin can be entered from a skidding turn. Excessive "inside" rudder
causes the ball to move towards the outside of the turn. Another entry to a spin
is from a wings-level condition. To do this you use heavy rudder to cause yawing
while holding full back and up yoke. The position of the ball will always be to
the outside in a spin. It moves to the outside regardless of spin direction.
Spins have both roll and yaw.
The standard spin entry and recovery of a one turn spin begins by making a
straight ahead stall, put in full rudder, after one turn put in opposite rudder
and forward yoke to break the stall. Recover from the dive quickly before the
speed increases. Moving the stick forward without reversing the rudder input
puts you into an accelerated stall. Putting the yoke forward will increase the
rotation speed.
The hands off recovery requires that you release the yoke but hold the rudder.
The yoke will remain full back. Apply full opposite rudder and when the spin
stops the yoke will move forward and break the stall without the pilot's input.
Recovery
Power off
Flaps up (not mentioned by FAA)
Opposite rudder until rotation slows
Positive forward elevator to break stall.
Neutral rudder and return to level (climb)
All spin recovery methods presume the aircraft is within utility category weight
and balance. Prior to attempting recovery the throttle should be retarded, the
flaps removed and the ailerons neutralized. Since the rudder yaw began the spin
it is the usual main course of action for recovery. Full opposite rudder is the
primary first move made very quickly to full deflection. Slow applications will
delay recovery. Depending on circumstances the full opposite rudder may take
from 1/2 turn to several turns to effect recovery. The recovery sequence always
begins with opposite rudder (Step on the high wing of the turn coordinator--step
on the heavy rudder pedal). Second, after the rudder starts to become effective,
move yoke full forward. Spin may speed up momentarily. The recovery actions do
not agree with your natural instincts. Spin recovery must be a learned response.
Moving the ailerons against the spin will delay recovery.
When the spin is broken we must once again use the rudder and yoke to return to
level flight. Speed will increase rapidly. These inputs must occur partially to
recovery stable flight without over-stressing the aircraft. A precision one-turn
spin should lose 5-600 feet and recovery at 2.5 to 3 Gs.
Spin Rebuttal
I was just looking through your website. You have a lot of good information
on there. Being an aerobatic pilot I was especially interested in the spin
awareness section. There's one statement in there that could get some pilots in
trouble if they don't recognize what's happening. It's in the recovery part
where your website states: "Recovery: Immediately, power off, opposite
rudder, forward on yoke always in this sequence. If rudder is effective yoke
forward may not be necessary. Otherwise, hold full application of controls until
recovery". Many people would read that and think they should push the
yoke all the way forward to recover. This would be a big mistake. The yoke
should go to neutral on recovery. If you push in full opposite rudder and full
forward yoke the rotation of the spin would first increase and then the plane
would cross over into an inverted spin.
The untrained pilot might not even notice the change because the rotation of the aircraft over the ground would be the same as it was before the attempted recovery. Just thought I should point that out. Someone might read that and go try it with no training and get themselves in trouble.
Bill Clute http://billcluteairshows.com
Spin Types
Inverted Stall
Requires inverted flight so you roll inverted, reduce the power, apply yoke full
forward to stall before rudder kicked in. Nose will drop out of the stall and
power is applied to continue inverted level flight.
Inverted flat spin
From inverted flight stall the airplane. Apply full rudder at the stall.
The nose indicates spin direction. Things are moving and sliding. To flatten the
spin, apply full aileron in the same direction as the rudder and apply full
power. To recover from an inverted spin use opposite rudder and hold yoke back.
It is possible to recover from a spin with full opposite aileron. It is also
possible to recovery by putting your hands over your head. It takes four full
turns so have plenty of altitude.
Flat
Entry into the upright flat spin is to first enter a conventional spin and hold
it until it stabilizes, two turns should be enough. Apply full opposite aileron
and add full power. You must force yourself to hold in the aileron. The aircraft
turns around its vertical axis at an deceptive high speed as it pivots about the
down aileron. Recovery begins with reduction of power. Lift both hands into the
air. Push full opposite rudder. It will take two turns to recover. Release the
rudder only when the turning stops but before it begins in the other direction.
Yoke will break the stall by itself. Recover from dive before speed builds up.
When yaw exceeds roll a flat spin exists. If in a flat spin with the nose within
45 degrees of horizon apply full aileron in direction of spin to reduce
autorotational effect of the retreating wing. You are in a flat spin when
release of back control pressure does not result in an additional lowering of
the nose. This is the only spin in which the use of ailerons is recommended.
You can do both upright and inverted flat spins entered from any attitude. A
standard spin entry to the left (upright) or right (inverted) from any attitude
with power or add power at after the break and outside aileron and away she
goes. Recovery requires 1/4 to 1/2 turn after power off.
Intentional flat spins are (almost?) always done inverted. That way, the rudder
is in clear air and not blanked out by the horizontal stabilizer. There are few
planes that can do them safely. For these planes, it is entered as a 'normal'
inverted spin. Then power is added. This brings the nose up to the horizon, and
the rotation is now almost pure yaw, with very little bank. Recovery is by
reducing power, which allows the spin to go 'normal' This is not the usual
response for an average plane! The few that can safely do flat spins have this
unusual characteristic!) For an upright flat spin, take any conventional twin,
and stall it with full power on one engine & full in-spin rudder. Unknown if
you can recover from it! Just that you can get in to it, without an 'aerobatic'
maneuver.
Accidental (incomplete)
Inadvertent spins can be differentiated from spirals since a spin has a rapid
descent with a low airspeed, while a spiral has a rapid descent with a high
airspeed. Inadvertent spirals are more likely than spins under IFR conditions.
Over the Top
Caused by top rudder in a tight climbing turn
Over the Top spin
It sounds to me like the instructor demonstrated a "spin over the
top" where you enter the spin from an accelerated stall with excessive top
rudder. In this spin entry you do indeed come around so that it appears to be
inverted going over the top. When you settle into the spin it is pretty well
developed. The airspeed will NOT increase significantly while you are spinning.
During your recovery you first stop the spin with full rudder against the yaw.
That leaves you in a fairly steep nose down attitude and stalled. A firm forward
pressure on the yoke will put you into a position where the airspeed can be
increasing quite rapidly. Of course you are then pulling back to return to level
flight. You do
not want to pull back so hard you bend the airframe with excess G forces, so you
ease the yoke back as the airspeed increases, treading the balance between
excess G force in the pullout and excess airspeed during the pullout. If you
keep the G force on the pullout below about 2 1/2 or 3 G's the airspeed can
easily build up close to Vne. You do want to be gentle on the pullout if your
airspeed is above Va! :-)
That description is fully consistent with a spin over the top followed by a
textbook recovery and a gentle pull out to level flight. That is a spin I always
enjoyed because it DOES appear to go inverted over the top! Much more fun than
spinning out the bottom of a turn or the standard prosaic straight ahead stall
and kick a rudder as it breaks to initiate a spin. When I learned to fly, one
was required to demonstrate all of the different spin entries with appropriate
recovery.
HighFlyer
Entry into an over-the-top spin:
--Enter stall from full power climbing turn
--At the stall apply full top rudder.
--Aircraft will abruptly go inverted in the opposite direction and into a
normal spin.
--Inadvertent entry likely during departure stall.
--By avoiding yaw (keeping ball in the middle) you avoid inadvertent entry.
Entry into an under-the-bottom spin
--Enter a stall from a gliding turn
--Add full bottom rudder and opposite aileron
--Nose will drop and lazily enter a spin
--Inadvertent entry likely during base to final turn
--By avoiding yaw (keeping ball in the middle) you avoid inadvertent entry.
Instructional Spin
--Not source of inadvertent spins
--Power off full stall with application of rudder
Unrecoverable/Uncontrollable
Spin
An uncontrollable spin is apt to occur when near aft C.G. Use of aileron to
try to raise the down wing can aggravate such a spin. If yoke is applied
before rudder an inverted spin may result. Because of higher stall speeds or
misapplication of rudder, inadvertent spins are more apt to occur out of
turns. Never demonstrate spins with an aft C. G., even at altitude.
Deliberate
A normal spin can be entered accidentally. A botched stall where the pilot
applies instinctive backpressure and aileron opposite to the direction of
rotation is the classic inadvertent entry. The instinct is to regain straight
and level without breaking the stalled condition. Every flyer should be
capable of safely entering and recovering from a spin. Spins, because they can
be accidental, should not be considered aerobatic. Rather, they are an event
that occurs in flying and should be a part of a flyer's experience.
Underneath
Caused by excess bottom rudder used to speed up the turn as when turning from
base to final.
Killer
Recoverable conditions leading to spins that kill every year. Recovery skills
depend on practice. The key to stall recovery is recognition followed by
promptly corrective control action. Every aircraft, even same type and model
will stall ever so slightly in a different manner. The inadvertent stall, as
its title states, does not occur unless you are distracted and unsuspecting.
You don't need to enjoy or fear stalls to practice. Go with an instructor.
Have the instructor set you up for an accelerated stall. (No longer an FAA
requirement but worth learning to do and make a recovery.) This is similar to
the stall that would occur on a tight turn from base to final. If possible get
an aerobatic instructor to take you through a spin series caused from
inadvertent stall situations.
More Spin Types
Accelerated spins with ailerons
Accelerated spins with elevator
Flat spins
Inverted spins
Inverted spins accelerated with elevator (these hurt!)
Inverted flat spins
Knife edge spins.
Other Recoveries
Spins to the uninitiated should only be introduced if and when the student
mentions the spins. Quarter or half turns are sufficient to demonstrate both
cause and recovery techniques. Spins, in and of themselves, do not seem to
improve flying skills. Accidental spins usually occur so close to the ground
that no recovery is possible.
Generic Spin
Recovery,
1. Power to idle
2. Ailerons neutral
3. Full opposite rudder
4. Yoke abruptly forward
This will work for practically every aircraft. However, older aircraft with
larger rudders and inherently more unstable were both easier to spin and easier
to make recover. The C-150/172 is engineered to be more stable and hence more
difficult to spin and more difficult to recover.
If
You Don't Use Procedures Recommended?
Power to idle or ...
Spin characteristics are accentuated with power on. The spin entry is faster,
the spin develops full rotation speed sooner and the angle of attack of the most
stalled wing will be higher. A recovery with power on may exceed the structural
limits of the aircraft.
Ailerons neutral or...
If the wing stalls at the tip rather than the root the drop will be abrupt and
without warning, causing instinctive application of aileron and further
aggravation. Trying to raise the stalled descending wing with aileron will
increase lift thereby increasing the drag inducing adverse yaw or yaw toward the
down wing. The increase in drag causes the stall to become more severe producing
even more roll. The spin can be prevented only if rudder/aileron inputs prevent
any slipping or turning at the point of stall.
Use of ailerons, even away from the spin direction, may again cause the spin
entry to be more abrupt, speed up attaining full rotation speed, give a higher
angle of attack, cause more difficulty in making recovery, and cause any
'recovery' to be merely the entry into another spin.
Full opposite rudder or...
When the rudder is applied so that the tail is not behind the nose there is a
span wise flow of air that causes the tip to stall before the wing root. Thus,
we have the no warning spin entry. This is more likely if the spin is done away
from the stall warning device. The rudder is actually the only effective control
you have. It is the only one that works against both the yaw and rotation.
Anything less than full application will be proportionately less effective. The
relatively small rudders of modern aircraft make even more important the full
correct application both in entry and recovery. (Note: The turn coordinator is
the best way to be sure of the direction of turn.) Rudder alone will not give a
recovery. As soon as rotation begins to slow the yoke must be moved abruptly and
fully forward.
Yoke abruptly forward or...
A slow or slight forward yoke may actually serve to aggravate the spin. As soon
as you first feel the negative G of the recovery release the yoke pressure.
Spins and recoveries should be learned and practiced so that there are just as
many recoveries as there are spins, unless you mastered swimming by going under
twice and coming up once.
Historic Spin Requirements
Early private pilot test allowed 15-degree error on recovery. Commercial after 2
or 3 turns allowed 10-degree errors. Instructors no error allowed. It is best to
avoid letting the number of spins exceed the number of recoveries.
Recovery
One recovery works for all general aviation aircraft. It requires extreme mental
discipline, however. The process is that as soon as the incipient phase begins,
that is loss of control, wing drop and turn, immediately pull the power off and
remove the flaps. Place your hands on your thighs, feet flat on the floor, and
the airplane will recover by itself.
Current
Spin Requirements
Stall awareness, spin entry, spins and spin recovery technique are now part of
the aeronautical section of the knowledge requirements for the private,
commercial and CFI ratings. The CFI who fails the spin oral will fail and must
demonstrate spins on the CFI flight test.
Endorsements (Instructor)
For Required Spin Knowledge
FAR 61,105 (6)
I have given _________#____ the flight training and ground instruction in stall
awareness, spin entry, spins and spin recovery techniques as requires by FAR
61.105 (6) and find him competent in this area.
Actual spin not required but recommended.
For Spin Awareness
I certify that I have given _____holder of pilot certificate # ________ ground
and flight instruction in stall awareness, spin entry, spins and spin recovery
technique and find that he/she meets the knowledge requirements required under
FAR 61....see above.
Dated...
Signed...
For Spin Training (Required CFIs)
I certify that in accordance with FAR 61.187 (a)(6) I have given ___#_____
flight training in spin entry, spins, and spin recovery techniques and he/she
has demonstrated instructional competency in those maneuvers.
Spin
References
Including AC 61-67B 5/17/91
Recommended reading: FAA-RD-77-26 GA Pilot Stall Awareness Study, AC61-21,
AC91-23,Practical test standards, AOPA Avoiding the Stall/Spin Accident
Spins
Revisited (Opinion)
If you don't want to spin -don't stall-
but if you do stall - keep the ball in the center while recovering-
but if you do spin - power off - full rudder opposing spin -
let go of stick (or follow flight manual procedure with stick) -
recover from dive while- not stalling and spinning again. Whew!!
Klein Gilhousen
Yaw Required to Spin
(Opinion)
In any turn, the inside wing is traveling slower than the outside wing. Not
much, but enough to make a difference in the angle of attack between the two
wings.
As the speed increases the angle of attack decreases. As the speed decreases the
angle of attack increases. You can see this clearly in a propeller. The pitch of
the propeller blade is twisted so that it is much flatter toward the tip, where
it is moving faster. This keeps the entire propeller near its optimum angle of
attack.
To initiate a spin, some yaw is required. The most insidious spin entry is the
"spin out the bottom." To spin out the bottom you make a skidding
turn. A skidding turn occurs when you do not have enough bank for your turn
rate. This is indicated by excessive rudder in the direction of the turn and
usually insufficient bank. This is the most popular spin entry on the base to
final turn and happens when you are trying to hold the bank down to the thirty
degrees you instructor asked for, and tighten the turn to keep from blasting
into the approach for the parallel runway, or at least to keep from going past
the centerline of the runway. You add extra rudder to tighten the turn. This
creates a yaw condition where the outside wing is speeding up, decreasing its
angle of attack, and the inside wing is slowing down, increasing its angle of
attack. This means the inside wing will reach stall AOA first and start to drop,
steepening the bank. Most pilots will react instinctively to this dropping wing
by using aileron to pick it up. That aggravates the stall by increasing AOA of
the dropping wing and decreasing the AOA on the rising wing. You find you cannot
pick up the inside wing, and the next thing you know you are entering a spin. It
tends to sneak up on you.
What should you do when the inside wing starts to drop? Pick it up with the
"top" rudder. That will yaw you back the other way and even out the
AOA on the wings. Then you must get the AOA back down below stall AOA. A little
forward pressure does that, and maybe a touch of power to regain your lost
altitude.
The less common spin entry from a turn is a "spin over the top" which
occurs when you have excess BANK. You now have rudder OUT of the turn. This
causes the inside wing to speed up, decreasing its AOA, while the outside wing
slows down, increasing its AOA and moving the outside wing toward stall first.
What will usually happen is the outside, or higher wing will start to drop. As
it does you will come level. Usually coming back to wings level will get both
wings unstalled and you merely add a little forward pressure to move away from
the stall and perhaps a bit of power to get your altitude back.
If you KEEP the outside rudder in, the yaw can continue past the level flight
attitude and the formerly outside wing will continue to drop entering a spin in
the opposite direction from the turn. You will likely be prepared to swear at
this time that you went through full inverted on the spin entry! This happens as
the wing continues to drop, while the other wing does not. You nose begins to
drop and the rotation starts causing you to roll over the "high" side
into the spin entry. It can be quite dramatic!
Either spin can be easily avoided by maintaining you airspeed at 1.3 Vs or
higher and keeping your banks reasonable and your turn coordinated. Even a
45-degree bank will only increase your stall speed to about 1.14 Vs, which
should still be well below your airspeed of 1.3 Vs at the time. Be aware though,
that a bank steeper than 45 can quickly bring your stall speed up to and above
1.3 Vs.
Once you complete the base to final turn, and are wings level on final then you
can start playing with uncoordinated flight. I recommend flying finals slightly
differently than normal flight. I forget about coordination on final. Use the
ailerons to bank the airplane sufficiently to slip enough to keep the airplane
aligned with the centerline. Use the rudders independently of the ailerons to
keep the nose of the airplane pointed toward the FAR end of the runway. Continue
this to touchdown. You have automatically made the proper correction for any
crosswind that you encounter! :-) If there is NO crosswind, you will maintain
alignment with the centerline with the wings level. It works for me! :-)
HighFlyer
Spin Statistics
January 25, 2001 AVweb's Question of the Week:
Question
"What, if any, benefits did you get if you received spin training?"
956 responses
Answers
--Increased knowledge of what an airplane can and cannot do. (6%)
--Increased confidence in my skills. (5%)
--Increased awareness of the need for precision during critical phases of
flight. (5%)
d. All of the above. (82%)
e. Other (3%)
Question
"Do you feel spin training should be required to become a certificated
pilot?" 1181 responses
a. Yes. (57%)
b. No. (7%)
c. Encouraged, but not required. (36%)
--Stall/spin articles appearing in aviation magazines continue to be well
received by readers, too. And the demand for stall/spin training at established
aerobatic schools is as strong as ever.
The Facts
--One-third of stall/spin accidents in an NTSB study involved pilots with more
than 1,000 hours of flight time.
--The median pilot experience of those involved in stall/spins was 400 hours
--We can profile who is most at risk of an accidental stall/spin as follows:
--It's the pilot who has logged fewer than 1,000 hours
--It’s the pilot who is on a daytime pleasure flight in good weather
--It’s the pilot who is in the traffic pattern
--It’s the pilot who is either turning or climbing.
Leading up to the inadvertent stall/spin
--It’s the pilot who will be distracted into making a critical error in judgment.
--It’s the 1/3 of the pilots who will fixate on the unfolding accident and
will not hear the stall horn.
–It’s the pilots with fewer than either 500 hours total time, or 100 hours
in type
1987 Statistics
--699,653 active pilots who logged an estimated 47.9 million flight hours.
--U.S. pilots averaged 68 hours each that year
--1990s average pilot flight time was only 50 hours.
--Average active flying career of a G. A. pilot is estimated to be 17 years.
--50 hours per year for 17 years pilot will accumulate close to 850 hours total
time.
--Most pilots will be in the of the stall/spin accident zone throughout their aviation careers.
--Mid-airs are statistically of less concern compared to the inadvertent
stall/spin.
--The stall/spin problem is neither like an everlasting rain cloud over the
airport It will get everybody.. .
--No segment of the pilot population is immune the stall/spin cloud over the traffic pattern..
--Average pilots on average flights fit the average stall/spin profile.
--Once entered into the spin the prospects for survival is greatly reduced.:
--One out of four aircraft fatalities are derived from the stall/spin.
--An 80 percent chance of serious or fatal injury in any accident involving the stall/spin..
--There is a 90 % chance that insufficient altitude exists in which to recover.
--19 % of stall/spin accidents are associated with the flight training process.
--A CFI is in the plane 11% of the time that a stall/spin accident occurs...
Expert Opinion
--All pilots will benefit from spin training
beneficial.
--A national spin training requirement for private pilots is not feasible..
--The G. A. infrastructure is not adequate for a safe program.
--There is a need to reinforce valid arguments, clarify the ambiguous ones, and debunk the myths,
--To expand our knowledge so pilots can reasonably improve
their stall/spin awareness.
--Spins place specific demands on pilots and airplanes.
--Spins are unforgiving of incapacity, incompetence or neglect.
AOP Study
–Uses myth that pilots believe aerobatics training makes recovery from
inadvertent spin at traffic pattern altitudes.
--I have yet to come across any pilot whose motivation to learn more about stall/spins was rooted in a belief that it would enable him/her to recover from a spin in the traffic pattern.
I have yet to meet rational proponents of spin training who
claim spin training would allow a pilot to recover from a spin encountered in
the traffic pattern.
--Pilots certainly are smart enough to realize that if a stall is allowed to
progress into a spin at traffic pattern altitudes, the probability of survival
is slim regardless of prior training.
--The primary reason proponents advocate, and pilots seek out,
additional stall and spin training is--surprise!--spin prevention.
–The advertised objective of spin training is to expand a pilot's knowledge,
experience, and skill set to prevent an inadvertent spin departure in the first
place.
--Another myth cited in the AOPA study is "watch your airspeed, or you're
going to stall this airplane!" The study claims that this myth is largely
propagated by flight instructors, …
--This airspeed myth is propagated by CFIs, textbooks and publications.
--Myth not supported by professionals in spin and aerobatics
training.
AOPA Pilot magazine states that FAA dropped the spin
requirement for the private certificate in 1949 because more pilots were killed
in spin training than in actual situations.
--Mandatory spin training was removed in 1949 by requiring stall instruction and
prevention training.
–Belief was that removal of spin and replacement of stall training resulted in
greater air safety.
--Stall was considered to be the most dangerous maneuver to
pilots;
-- Hope was that anti-spin- aircraft would come into use. Never happened.
--A survey in1997 found
--Programs on spin/aerobatics training was 5 to 29 years.
–About 135,000 hours of instruction given:
--Over 250,000 spins. or 12,000 vertical miles of flight.
–No accidents. to this date in 3003.
The New AOPA Study
--The study reinforces the importance stall/spin
awareness and prevention.
--Legitimate spin training is capable of supplying the ability
to avoid spinning.
–Proper spin training will increase the importance of spin avoidance to the
pilot.
--The practical knowledge about mechanisms of spinning, the importance of operating limitations and misapplied controls is a life and death matter to every pilot. Your instinct will kill you.
General
Aviation Pilot Stall Awareness Training Study
FAA-RD-77-26, September 1976, 75 Instructors
--Spins should be required -- 65%
--Pilots who had stall/spin awareness training--without spin training--were 33% less likely to enter a spin from an inadvertent stall.
--Pilots who had stall/spin awareness training with spin training—were 100% less likely to spin from an inadvertent stall..
--This FAA study has fueled the changes made to the training required regarding stall/spin awareness since 1976.
--This FAA study is not a reference used by the anti-spin
training advocates.
Spin-Statistics
--13,680 G.A. accidents 1973-83
--Single-engine airplanes 1 or 2 people on board.
--Student pilots lowest stall/spin fatality rate at 4%
--30 % of private pilot accidents caused by lack of skill or overconfidence..
--ATPs 7.5% of flying population have nearly 10% of spin accidents.
--ATPs have 3.5 %of all fatal and below 3% of non-fatal G.A.
accidents.
–G.A. no more dangerous for ATP than professional flight.
–Overconfidence a greater factor than lack of skill in 60 percent of the
ATPaccidents
--Aerobatics accidents, 13.7 % for ATPs and 6.5 % for private pilots;
--Fatal aerobatics accidents, 50 % ATP and 20% private pilots.
--ATPs to perform aerobatics at unsafe altitudes.
–ATP fatal stall/spin accident component in non-aerobatic phases of flight,
were responsible for 13 percent of the fatalities
--ATPs aerobatics resulted in 38% of spin accidents.
--ATPs do better than average in normal flight
-- ATPs doing aerobatics are overconfident and under trained.
–ATPs are subject to the same human failings as other pilots.
--All pilot classes show deficiencies in training, judgment and stall/spin awareness
--Experienced pilots have 2.5 times as many accidents involving spins than do student pilots.
Flying with
Instructors Can Be Dangerous
--60 percent of stall/spins with an instructor aboard.
--91% of fatal stall/spin accidents with an instructor.
--20% of stall/spin accidents during instructional flight...
--Students have a better record when solo than when with an
instructor
--Students are two times more likely to have a stall/spin accident when with an
instructor.
Instructional Background (1993)
–94% relied on popular literature;
--96%also instructors relied on their own instructors.
--95% failed ever to receive training in spin dynamics or conditions causing an inadvertent spin.
--94% of the instructors didn’t know spin certification
FARs, nor limitations imposed.
--98 percent said training consisted of no ground instruction and a mere two
spins--one in each direction.
--All had logbook endorsements certifying that they were competent to teach spins.
--97% unaware of the FAA spin changes of 1991 included in AC
61-67B.
NTSB
Aerobatics Accidents (1972-1974)
--Stalls and spins were primary accident types in
49 of 105 cases A 47% percent stall/spin accident rate. ----Most stall/spins
were unintentional and were related to other aerobatics maneuvers at unsafe
altitudes.
--A number of the stall/spins were intentional at safe altitudes.
NTSB's Analysis
--Most pilots had some previous spin instruction
--Knowledge and proficiency minimal.
--Not fully aware adverse spin characteristics caused through improper use of the flight or power controls..
--Not aware of need to use a precise technique to achieve the
recovery."
--24% of the accidents involved CFIs/
--Age ranges 11 > 30; 10 > 50; 3 > 50
--Flight time 8 > 3000; 2<600;
--Time in type 14 < 300; and 6 of the 14 <
--CFIs were in 23% of the accidents and 39% of the spins.
--58% of crashing instructors did so in a spin.
Stowell’s Hypothesis
--Pilots spend only 6% of time near airport
--This 6% accounts for 57% of accidents.
--Disproportionate amount of student time spent at airports.
--Airport pattern flying has high percentage of slow-flight
flying.
–Landings per hour is far lower for pilots than for students.
--Student are most experienced in flight region prone to stall spins.
--Best possible rate theoretically is at 2%.
--Student rate of 4% as good as practical.
–Airplanes type-certificated prior to 1950 with 500 registered
--Fatal stalls-plus-spins accident rate for this subset of airplanes was 42%.
--In 1970 the same airplanes were in 48% of the stall/spin
accident rate between 1945 and 1948
--Kit airplanes between 1983 and 1997 of 701 fatal accidents, unintentional stall/spin
preceded ground impact
in 45 percent of the cases.
–It seems that removal of spin training in 1949 had little effect on the
stall/spin accident rate.
--Greatest change in the stall/spin accident rate came about
as a result of the influx of newer designs.
–Appears that previous "spin training" prior to 1949 and "stall
avoidance" were equally effective.
--With the newer designs, the stall/spin accident rate declined.
--The stall/spin accident rate remains the same as does the make up of our flight lines.
POH Stall Altitude Losses
1.Intentional stall tests;
2. Performed at altitude
3. Wings level
4. Held into spin for one turn before recovering
3. Conducted under ideal conditions;
4. Using airplanes finely tuned to exact factory specifications;
5. With FAA-DER Test Pilots at the controls;
6. Without emotional duress.
Real-life Conditions:
--Inadvertent stall/spin
--Loss of twice POH altitude
--Presence of shock and surprise
--Duress due to altitude
--Banked wings
--Stalls can lose as much altitude as spins before recovery
Stall vs Spin
--He who reacts instantly and correctly a stall will recover sooner than he who
enters a spin.
--He who freezes on the controls at the onset of a stall will lose more
altitude than the pilot who spins.
---Any meaningful comparison between the stall and spin must state the
conditions and assumptions.
--Those advocating the anti-spin training agenda always attempt to measure the
advantages of spin training against an hypothesis that is illogical.,
--He who has an incomplete understanding of stall/spin dynamics and improper control is an active participant in creating the event.
--When is the probability of a spin trained pilot encountering an inadvertent
spin departure in the traffic pattern greatest? Think density altitude.
Protecting Yourself
from Stall/Spin Accidents
--Read FAA AC 61-67C, Stall and Spin Awareness Training
–Follow up on AC61-67C recommendations
--Look at AC 61-67B
--Learn about the 30-degree bank
Required Knowledge about
Stalls and Spins
--Stall/spin effects and definitions
--Weight & balance considerations
--Airworthiness and certification standards
--Wing contamination effects
–Distractions
--Human factors
--Vestibule-ocular illusions
--Typical stall/spin accident scenarios
--Warning signs
--Stall recognition
--Types of stalls
--Stall recovery
--Secondary stalls
--Spins
--Primary
--Causes
--Types of spins
--Spin recovery
--Typical recovery errors
--Spiral recovery.
Knowing Stalls
--Stall avoidance practice at slow airspeeds
--Power-on stalls
--Engine failure while in a climb followed by a gliding turn
--Cross-controlled stalls in gliding turns
--Power-off stalls
--Stalls during go-around
--Elevator trim stalls.
Knowing Spins
--Power-on and power-off stalls
--Turning stalls
--Spin avoidance training using realistic distractions
--Intentional incipient spins
--Spin entry, spin, and spin recovery
--Spin-to-spiral transitions
--Aggravated spins
--Inadvertent stall
--Spin departures from unusual attitudes.
--Pilots seek to expand their comfort levels
--Pilots seek to develop additional awareness to prevent a stall/spin departure
close to the ground:
Stepping on the Sky
Questions
I heard it somewhere. What does it mean? It's in relation to spin training..
Does it mean to step on the side of the rudder where you see the most sky?
Answer
It's a term that is part of the most popular unusual attitude recovery
mantra. It deals with rudder use during unusual attitude recovery and is part of
the process:
1. Push. Push the autopilot off and push the yoke to unload any Gs.
2. Power. Increase if nose is high; decrease if nose is low.
3.. Rudder. If nose is low, "Step on the sky".
4.. Roll. Roll wings level before pitching up to horizon.
5.. The important thing to remember in all this is to roll to the nearest
horizon.
Dudley Henriques
In Charge of the Spin
Try to really learn the aerodynamics of the spin such as why a
descending stall will spin under the bottom and a climbing stall will spin over
the top. Also try to understand how using rudder to control yaw affects the
angle of attack of each wing and breaks the stall and also why the recovery may
snap into an opposite spin if not performed properly.
Once you understand the why you will remove the uncertainty and confusion and
will
control the fear. You will feel in control of both
your brain and your aircraft.
At this point you will begin to really enjoy spins and will be able to
experiment with variations of throttle and aileron to get a cleaner entry or to
stabilize the spin. Situating over a road or such and counting half rotations
and doing exercises like recovering on a heading will really sharpen your
positional sense and you will need to know how much to lead your recovery in
order to recover on the desired heading. When you get good at that get your instructor to call the heading to recover on after the spin has
developed and you will learn to do the mental calculations during the spin which
will give you great confidence.
Pick an aircraft with good spin characteristics. Using an aerobatic rated
aircraft and parachutes combined with lots of altitude will also help with the
confidence factor.
A Spin Virgin No More
Well as most of you know by now, my Commercial checkride is on hold while we
wait for my FBO's only complex aircraft to get it's replacement engine.
So, last week (when my checkride had to be cancelled due to the Arrow III going
off-line), I asked my CFII if we could work on some of the CFI training. More
specifically, I asked him if we could start with working on the spin
endorsement.
Today was the day! We started with some ground instruction regarding spins,
which included me explaining the mechanics of a spin and being questioned on
what were the specific caveats related to the aircraft we were using (a Cessna
152). My initial 'explanations' missed the mark initially (that is being plain
enough to serve as an apt explanation to a student who had no understanding of
spins), but with my CFII's help I was able to 'rein-in' my explanation so that
it was more clear and concise. We did the weight and balance calculations to
make sure that we would be well within the W & B
'envelope' and we were.
After our ground instruction session together it was time! I told John that I
had only one 'disclaimer', that being - I had never done this before and wasn't
sure how I'd 'be'. Though I went on to say that my level of curiosity had easily
grown to a level that easily out-measured any fear/concerns I may have about
spins. John, told me that often he had heard from his students that the actual
spin was far less ominous/frightening than their (i.e., the students) imaginings
were. I told my CFI that may very well be and the 'proof would be in the
pudding' so-to-speak; that is after I had my first spins.
Took off from Reid-Hillview and headed out to the practice area. John had me
climb to 5,000 feet and then perform some clearing turns. As he mentioned to me
earlier, he reminded me that he would demonstrate the first one (with my hands
and feet on the controls - following with him) and then the second spin, I would
do the entry and recovery with him verbally coaching as necessary.
Here it goes! John reduces the power to idle and just as the plane begins to
stall he steps on the rudder in the direction he wanted to begin the spin (he
picked my side to start with). I was amazed how the 152 responded by immediately
entering the incipient spin and then 'full' spin. I have to tell you, the first
spin was not 'scary' (and this is not male bravado speaking, at all) rather it
was first just a matter of getting my brain to 'comprehend' all the new 'visual
inputs' it was getting. The earth was turning below in my windscreen, I was in a
spin.
Then John smoothly applied opposite rudder (the rotation stopped) and released
the back pressure on the yoke and we were now in a steep dive which he carefully
pulled us out of. .I must say that the worst part (at least for me) of the
maneuver are the 2 to 2.5 G's you pull when coming out of the dive. My head and
the stomach did not enjoy that part, but once we were back to straight and level
and 'normal weight' <g> I felt a bit better. Though I did feel a bit
'heady' (NOT dizzy) more just that my inner ear had been put though a good
workout (specifically the semicircular canals). I remember experiencing
something similar during recovery from unusual attitudes practice from my other
pilot training.
I told my instructor that the spins weren't anywhere what I had imagined them to
be like. I told him too that I felt a little bit heady, but that I wasn't going
to lose any lunch yet, but I would keep him apprised of my status as we went
through the maneuver.
So, now it was my turn. I (though it wasn't necessary) told my instructor that
he might want to follow me through on the controls just in case I had an
unexpected reaction resulting in an incorrect control input. John told me that
if he needed the plane he would say 'my plane' and I would turn it over to him
if necessary; though he went on to say that he really didn't think I was going
to have a problem.
I did some more clearing turns. Brought the power to idle, kept raising the nose
until the wing stalled and then stepped down on the left rudder - over we went -
incipient spin to one full spin and recovery. I was impressed with myself. Not
really a trace of hesitating to enter the maneuver nor delay in recovery - after
all, I had never done this before; just read about spins endlessly <g>.
Head and tummy doing 'decently'. Surprisingly, I was not having any ill feelings
about the spin itself, rather it was that g-pull at the bottom that my
physiology didn't care for in the slightest.
I gave my 'head & tummy' status report to John; all seemed to be okay, for
the most part. So John said he would demonstrate (with me following through on
the controls) an incipient spin, followed by 2 full spins. After he performed
them he had me do the same. At this point I was already to do the spin,,,
actually (except for the head-tummy issues) I was eager to do another spin,
myself. So, in I went,,, recovered and of course; yuck that g-sensation thing.
I told John that I could probably do another but that should probably be 'it'
for the day as far as what my head and stomach would likely tolerate (I was just
being safe, 'cause I haven't gotten sick in a plane yet and I would like to keep
my 'perfect record' <grin>). John said that would be just fine and that he
would end our session demonstrating (with me following through) a 3 turn spin
with recovery. At this point my brain was becoming quite accustomed to the
visual input and I was actually 'casually' (in a manner of speaking <g>)
counting each full turn and then recovery..... We timed the session quite well
as I was stopping just at the point where there would be no 'point-of-no-return'
as far as nausea might go.
Headed back to RHV, landed in the slight crosswind (still got to confess that
the heady-nausea thing hadn't left me yet) and we tied down the plane and
debriefed. I thanked my instructor for making it such a positive experience
(after all, I liked the spins,,, wasn't his fault my nausea 'threshold's needing
a little more exposure).
I drove home, but not before stopping at a local supermarket to pick up a bottle
of ginger ale and some pretzels. Like I told my instructor there was no way I
was going to eat a hamburger right now. So, I sipped on the ginger ale and
carefully nibbled at the pretzels, since it was all I could safely get into me
at the time.
Now it is almost 7:40PM and it wasn't 'till about 40 minutes ago that I started
to feel 'normal' again (finished my flight lesson at 3PM).
Well, I did it! My first spins!!! They weren't the visual 'dragons' that I had
imagined them to be and by the 3rd one I was actually kind of enjoying them
(though I was clearly not enjoying the mild motion sickness issues on the
g-pullout). Regarding the motion sickness issue, I'm not too concerned. As I've
learned from the past; it is just a matter of exposure.
Cecil Chapman
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