• Myth number 1: If you encounter an accidental spin, unload angle of attack and hold the control wheel/stick full forward.
• Myth number 2: If you snap out of control accidentally, hold full throttle to keep the air flowing over the tail and drive it out with power.
• Myth number 3: Weight and balance is not a problem as long as only one or two people are aboard.
• Myth number 4: I know the airplane is not certified for spins but I spin mine all the time so it must be safe.
• Myth number 5: In an accidental spin, use standard light plane spin recovery procedures.
Myth numbers 1 and 2 are alive and well. Consider the following mishaps:
The NTSB preliminary report was terse and to the point. On December 14, 2000, a Pitts S-2B crashed in the Everglades near Weston, Fla. Both pilots were killed. The Hollywood North Perry Airport control tower received a radio transmission saying Mayday, Mayday, Mayday: Pitts 269DB in an unrecoverable flat spin at 3,500 feet.
In another case, the pilot of a Pitts S-2A was killed while practicing his airshow routine. The airplane made a high speed pass across the field from east to west at an estimated altitude of 200 feet. This was followed by a near vertical climb to approximately 2,000 feet. The airplane then rolled inverted on a westerly heading and rolled upright. This was followed immediately by a snap roll to the right. At this point the airplane entered a spin. One witness, an aerobatic judge, said the snap roll was entered at too low an airspeed.
Perhaps the most significant information in the preliminary report was a witness statement that the engine was operating at a high power setting and the propeller was turning during the airplanes descent. During a badly delayed recovery, he crashed at high speed between the runway and parallel taxiway in a near-level attitude.
Some years ago another veteran aerobatic pilot, flying a Pitts S-1, was practicing for an airshow at a southern California airport. In this case he was attempting a tail slide maneuver wherein the aircraft stalls vertically and falls backward tail first, then eventually reverses itself. In this case the pilot was slightly off in vertical pitch. As his airspeed decayed and the airplane stalled, an amateur movie photographer captured his subsequent errors.
To correct his near vertical attitude the pilot applied aileron and rudder along with a hefty amount of forward (nose down) elevator. As his airspeed decayed the control inputs were apparently ineffective and the deflection angle increased. The aircraft stalled and fell backward through its own smoke trail. Then, still at full power and with what appeared to be full aileron deflection and full nose down elevator deflection, the aircraft immediately entered an inverted flat spin. The airplane crashed, still at full power and full nose down elevators, in an inverted flat spin.
These accidents were reminiscent of the problem the Air Force once had at the prestigious Fighter Weapons School at Nellis AFB, Nev. During mock dog-fights, or air combat maneuvering, it had become vogue by some instructors with no combat experience to allow an encounter to degenerate into a slow speed contest. (In combat you never slow down to near stall speed unless you have a death wish.)
The airplane was the F-100 Super Sabre. It had very strong adverse yaw when ailerons were deflected. At a slow airspeed, an abrupt aileron input would quickly snap the aircraft into an over-the-top spin. For example, a hard right control input caused adverse yaw from the down going left aileron to precipitate a snap over the top to the left.
It was easily recoverable, again by using adverse yaw. For example, when spinning to the left, place the control stick full left, or with the direction of rotation. Adverse yaw from the downward deflected right aileron was more powerful than rudder and recovery occurred quickly.
During this period many of the new generation fighter pilots were coming from Air Training Command and had extensive experience flying the Cessna T-37. The Tweet, as it was called, had entirely different spin recovery characteristics and procedures from any of the Century series fighters. The Tweets emergency recovery procedure was to slam the control stick full forward and hold it there. Add opposite rudder if you could determine the direction of rotation, but the airplanes rotation rate was extremely fast and sometimes disorienting.
While reducing or unloading angle of attack is obviously necessary in any stall or spin situation, the emergency recovery being taught at the FWS required that, with a snap out of control, the pilot was to slam the control stick full forward and hold it there. Naturally it was expected that the pilot would recognize the moment of recovery and pull out of the resulting dive.
Yet, like the aerobatic pilots in the accidents described, these fighter pilots were not correctly recognizing the moment of recovery. This procedure led to a long series of major spin accidents. The unload procedure quickly spread throughout the Air Force and inevitably led to several inverted flat spin crashes.
Compounding the problem was that the heavy fuselage-loaded fighters required a spin recovery procedure that was exactly opposite the wing-loaded T-37. This, combined with a lack of spin training in like type aircraft, prevented the aircrews from recognizing the moment of recovery. One particular super-eager FWS instructor had a student crash in an inverted flat spin on each of two back to back instructional flights. Upon departing each one held full nose down elevator past the recovery point. This caused the airplane to go from an upright to an inverted spin.
A subsequent study found that only one of the Top Gun instructors could accomplish the correct spin recovery control input on the first try, and that one botched all subsequent attempts. Thus a spin training program was recommended.
It was considered too dangerous, however, and was never implemented. Meanwhile the fighter spin accident rate continued at a breath-taking rate. An annual accident rate of 12 to 15 mishaps per 100,000 flight hours was common. Modern trainers and fighters have improved aerodynamic designs and computer protected flight controls, and the spin accident rate is less than two per 100,000 hours.
Just Ancient History?
The value of the history lesson is apparent when you consider that the same erroneous T-37 thought process seems to have been perpetuated among modern non-spin trained civilian pilots.
Many pilots subscribe to the notion that, in an accidental spin, unloading angle of attack by placing the control wheel/stick full nose down and holding it is the total solution to a loss of control or departure. While unloading is, in fact, the necessary first step, there is no one-size-fits-all magic control input that, if held to infinity, guarantees recovery in every airplane.
The pilot must still consciously fly the airplane and use control inputs appropriate to the circumstances. Above all, he must be able to recognize the moment a stall is broken and promptly return the controls to normal.
The simple answer is that spin awareness training is necessary – but the problem with that conclusion is that it does not explain the inappropriate recovery of highly experienced aerobatic pilots. The answer must be a lack of complete understanding of the dynamics involved, combined with a momentary element of panic.
These spin accidents, in our view, illustrate how a misunderstanding of emergency spin recovery procedures has permeated general aviation. The accident record documents what we consider a dire need for spin awareness training, regardless of the FAAs position on the matter.
Certification standards require that all single-engine airplanes must be recoverable from a one-turn spin. In reality, a one-turn spin is a delayed stall recovery and the spin is actually in its incipient phase.
The incipient phase is defined as the transient period between loss of control and a fully developed spin wherein the aerodynamic and inertial forces have not yet balanced. If the spin occurs at slow speed, normally the incipient phase requires about two full turns before entering the steady state phase. At higher speeds the incipient stage is longer since there is more energy to dissipate.
For example, a snap roll is a high energy incipient stage spin. During this phase virtually all the single-engine GA airplanes recover if the pilot simply neutralizes the flight controls while simultaneously bringing the power to idle (assuming the elevator trim is not full nose up). Consequently, pushing the stick full nose-down and holding it can be hazardous. As the elevators go past neutral – assuming a normal CG – most aircraft recover quite rapidly. If full nose-down elevator is held past that point, the aircraft goes to an inverted stall/spin position.
The Tomahawk POH provides good advice: As the rudder hits the stop, (opposite the direction of rotation) rapidly move the control wheel full forward and be ready to relax the forward pressure as the stall is broken. … In all spin recoveries the control column should be moved forward briskly, continuing to the forward stop if necessary. This is vitally important because the steep spin attitude may inhibit pilots from moving the control column forward positively. The key words here are be ready to relax forward pressure as the stall is broken.
In all single-engine GA aircraft I know of, recovery is quite rapid if power is reduced to idle and controls are neutralized. In the Tomahawk, an accidental departure requires full anti-spin controls.
Weight and Balance
Myth number 3 says weight and balance is not a problem with stalls and spins as long as only one or two people are aboard. Yet what many pilots and flight instructors dont realize is that when practicing slow flight, stalls and especially spins, the weight and balance is critically important.
A Cessna Pilot Safety and Warning Supplement states, An airplane loaded to the rear limit of its permissible center of gravity range responds differently than when loaded near the forward limit. The stall characteristics of an airplane change as the airplanes load changes. The publication notes that the stall characteristics become progressively better as the center of gravity moves forward.
To be approved for spins, an aircraft must be certified in either the Utility or Aerobatic category. Most airplanes certified in the Normal category have a relatively wide CG envelope, yet in the Utility or Aerobatic category the CG range is very limited. The Pitts S-2A/B is a good example. The airplane has an expansive CG envelope when operating in the Normal category. But in aerobatic category the CG range is quite limited.
Thus two heavy pilots and a full gas tank can limit the airplane to Normal category maneuvers only. And if you should spin it, recovery will take much longer or require much more nose down elevator. Then, too, as the examples show, in some cases it may not recover.
Some years back, two Piper Cherokee 140 Cruisers, both with a student and instructor, crashed in unrecoverable spins. Both were found to be victims of only a very slight violation of the Utility category CG envelope.
In one mishap the instructor had advised approach control they would practice spins between 4,500 feet and 2,000 feet. Shortly thereafter one of the pilots transmitted, It still wont come out. Mayday, mayday.
Post-crash investigation showed that at 1,902 pounds gross weight, they were below the maximum gross weight of 1,950 pounds for Utility category maneuvering. But unfortunately, because of 11 gallons too much fuel, they were a half-inch aft of the CG limit.
In the Normal category, the Cruisers CG range is 10.1 inches. However in the Utility category the CG envelope range is only 0.7 inch. The accident report said the pilots had conscientiously limited their fuel weight, but it wasnt enough. In the Cruiser the occupants sit within 0.3 inches of the empty weight CG. Meanwhile the fuel tank is 9.2 inches aft of the empty weight CG. Thus every drop of fuel aboard moves the balance point rearward. Therefore with 32 gallons aboard at the time of their crash, they were 0.5 inch aft of the 86.5 inch aft datum limit.
In the other mishap, which was virtually identical, the pilots were operating with the CG 0.3 inches aft of the limit.
These two examples point to another problem. The pilots busted the CG envelope despite their conscious attempts to comply with the limitations. One problem can be traced to the use of the sample weight and balance found in most Pilot Operating Handbooks. The sample is, of necessity, based on so-called standard weights. So a standard male pilot is shown at 170 pounds. The problem is, many pilots dont account for the fact that they or their passengers weigh-in at more.
In some aircraft, including the Cruiser, even the seat position is a factor. For example, Piper subsequently issued Service Bulletin 753, which warned pilots that only the center seat track position would provide the 85.5 inches shown in the POHs sample weight and balance problem. For a long-legged pilot, each seat track hole aft of center moves the arm 1.25 inches farther aft.
Some years ago I was aboard when a Pitts S-2A crashed because of this same weight and balance problem. It was my first flight in the airplane, and a weight and balance calculation never occurred to either of us. My host had just acquired the magnificent machine from the factory. It was so new the Hobbs meter showed only 15 hours.
The owner/pilot was an experienced and highly qualified aerobatic pilot. However, with a second person aboard he typically would not do spins or maneuvers involving negative gs.
In this case, however, he offered to make an exception because of my previous studies of the Air Force fighter stall/spin problem. He pulled up to the 3,500 foot overcast and put it into a left turn spin. After four fast rotations he applied recovery controls, but there was no noticeable effect.
The airplanes attitude during the spin was very nose low, so I assumed his recovery, with the control stick slightly aft of neutral, was correct and would prevent accelerating the already fast rotation rate. His previous experience using this technique with only one person aboard produced a quick recovery. But with my 200 pounds in the front cockpit and a full gas tank between my knees, it had no effect on the spin.
Just before impact the pilot added full power. The gyroscopic effect caused the airplane to snap upright and pause, then slowly begin the first rotation of a flat spin to the left.
We hit the ground during the initial transition to the flat spin mode and fortunately both of us survived. During later calculations we discovered that our CG was about one inch aft of the aerobatic category envelope but well within Normal category loading. It would have been worse if my friend had weighed more than 165 pounds. In this case full nose-down elevator probably would have resulted in recovery.
The problem is also common in aircraft such as the pre-1992 Citabrias, which can carry extremely limited fuel with two people aboard. For example, two 190-pound pilots can carry only 17 gallons of fuel in a lightly equipped 7GCAA. The 190 pounds per person would include the weight of parachutes and flight gear and would be reduced by any optional installed equipment.
As you can see, your weight and the amount of fuel aboard is critically important when maneuvering in the Utility or Aerobatic category.
Myth number 4 is that you can safely spin airplanes not certified for spins.
A classic example of this so – called playing test pilot occurred several years ago in a Grumman American Tiger. The aircraft was not spin-certified, and this was stated in the POH. Yet according to the pilot/owners 12-year-old son, a frequent passenger, Dad spun the airplane all the time. He enjoyed doing spins.
One Sunday he took his much heavier son-in-law flying and flew over their house. With his family watching he kicked the airplane into a spin and during recovery it went flat. Both occupants were killed.
In another instance a Cessna 185 owner tells of a practical joke that almost backfired. He was returning at dusk from a Colorado ski vacation with his wife in the seat beside him and his daughter in the back. Both passengers were asleep. In the baggage area he had suitcases and all manner of outdoor equipment.
Despite the POH statement that Intentional spins are prohibited in this airplane, he, like the Tiger pilot, was proud to say he practiced spins regularly. As he flew over the Mojave desert and reached his descent point he thought it would be funny to spin down to lower altitude and give the ladies a thrill. But he ended up scaring himself when the Skywagon was reluctant to recover.
He hadnt read Cessnas Safety Warning supplement that states clearly extremely aft CG locations will tend to promote lengthened recoveries since a more complete stall can be achieved. Changes in airplane weight and distribution can have an effect on spin behavior since increases in weight will increase inertia.
Because certification in the Normal category includes only demonstration from a one-turn spin, the pilot has no idea what the airplane will do as the spin develops more fully.
Truth be told, you are not playing test pilot when you spin it anyway. A true test pilot would have an anti-spin recovery chute in the tail and would have reviewed wind tunnel studies of the airplanes behavior.
Some years ago a NASA test pilot rented a Tomahawk from a local FBO and accomplished an unofficial series of spins. Each spin was recorded on videotape. On the 11th spin he recovered early because the spin seemed to be flattening. Since the undertaking was unofficial, further testing was stopped because they were not funded to purchase the airplane and install a spin recovery chute in the tail.
The Tomahawks history of odd spin behavior and unrecoverable spins is well known in flying circles and has been documented in Aviation Safety. Following one flat spin incident, the FAAs Eastern Region chief test pilot recommended a study of the possibly adverse effects moving the pilots seats to the aft stops. The FAA says it has no record of any action on this recommendation. Meanwhile, despite its certification for spins, the accident/incident record shows that the Tomahawk has an unrecoverable flat spin mode.
Standard Spin Recovery
By now, its probably obvious there is no such thing as a standard spin recovery that fits all general aviation airplanes.
In the late 1930s NACA devised a so-called standard recovery using an open cockpit Waco biplane. That original recovery required opposite rudder and control stick full nose down.
In the late 1940s the agency published a modified recovery that called for opposite rudder and the control wheel/stick neutral or just forward of neutral.
Current wisdom is that the recovery published in the Tomahawk POH may be the closest thing to a standard spin recovery, since it advises to rapidly move the control wheel full forward and be ready to relax the forward pressure as the stall is broken. Another POH advises to begin moving the control wheel/stick toward the forward stop but relax the nose down pressure if and when recovery occurs. Yet as the Air Force study showed, someone without spin training is unlikely to get it right the first time and recover.
As further documentation of the need for spin avoidance training, an FAA inspector tells of a Private Pilot flight test wherein the student failed to use any rudder during a power-on stall. Because she had been countering torque and P factor with ailerons only, the Cessna 150 snapped over the top to the left when it stalled. At that point, the student applied full power and pulled the control wheel full aft; then screamed I dont know what to do.
The inspector retarded power and asked her, What are you going to do? She then released the controls and the airplane recovered immediately. Further questioning revealed she had never heard of torque or P factor, nor had she been taught to use rudder in controlling the airplane.
The moral to this story is if you accidentally depart, simply chop power and release the controls. (This assumes you havent trimmed full nose-up elevator.)
It is extremely important that you chop the power and have the ailerons in the neutral position. Then if the aircraft doesnt recover immediately begin moving the control wheel/stick nose-down until it does recover. If you get to the full nose-down position and it still hasnt recovered, then it just wasnt your lucky day. You were probably overloaded and out of the CG envelope. Under these circumstances all light planes will recover from the incipient phase of a spin.
As for the direction of rotation the turn needle in the turn-and-slip indicator or the small airplane in the turn coordinator will always indicate a full tilt in the direction of rotation. Your job is to simply stomp on the opposite rudder. Without spin awareness training youll probably be so petrified that youll just sit there trying to think of the proper procedure – perhaps animated by a practice scream.
During a spin, airspeed will be stabilized at some IAS other than power off stall, but at the moment of recovery the airspeed jumps and begins moving. Upon recovery, in some aircraft, the rotation may continue. But an increasing airspeed indicates the stall/spin is broken and you are now in a spiral dive.
Because of recovery dive-out speeds, landing gear and flaps are not recommended. In fact in some aircraft flaps can delay spin recovery.
The main point of this discussion is to convey the notion that, regardless your total flying time, you must be thoroughly trained in stall and spin awareness. Otherwise during an accidental departure studies show that you are very unlikely to apply proper control inputs to recover.
You simply must know how to fly the airplane. And that takes training.
-by John Lowery
John Lowery is a former Air Force pilot, accident investigator and corporate pilot.