Soaring myths, stalls and landings
To teach your kids to read requires a four-year college education. To teach your kids to fly requires very little training.
Schoolteachers must take a competency test from time to time. The test questions are embarrassingly simple, yet even with an extensive education, fully 25% fail. Glider flight instructors are no better and often worse.
Assuming stalls are a prime problem in aviation safety, I once gave a test to 80 glider CFI’s where not a single person got the question correct.
The test question? “What are the signs of a stall?”
The FAA states when teaching stalls, “The real objective is not to teach how to stall an aircraft, but to teach the signs of a stall.”
Emphasis in training is supposed to be stall prevention and recognition, yet even CFIs don’t know the basic knowledge to the minimum FAA standard that can allow pilots to fly safely.
One of the major persistent myths is “75% of aviation fatalities are the result of stall/spins. I’ll address this myth later.
The basic, provable problem associated with glider safety, is glider pilots do not have the fundamental knowledge to allow them to fly safely.
Many years ago, I gave a ten question, multiple-choice test including questions every pilot should know to glider pilots at the Hartford SSA convention. (During a turn on aerotow, which side of the towplane should you see?) The average score was 36%.
Similar tests given over the years produced similar results. No improvement despite efforts of the SSA, FAA, AOPA and others. It is the same in other countries.
Who are these pilots?
Demographically, glider pilots are well educated, above average intelligence, older people who are often the movers and shakers of society. They have experienced the educational system on a higher level.
Yet, they will seek out the easiest way to obtain their glider license and permit; even seek out, sub-standard flight training.
We routinely see this at our school. A person will call and want to obtain their rating the minimum time possible. Transition pilots are the worst. They can go to another school and make the transition from a private or commercial power rating to a similar rating in gliders in as little as three days.
If you review the government training requirements, it is impossible to do the required training and flight test in three days. We have trained some of the most skilled pilots from astronauts, military and airline pilots. Even the very best of the best take several days to accomplish a transition course.
Otherwise intelligent people will seek out the easiest path to a rating, which results in substandard pilot skills and knowledge. As long as this substandard training/knowledge/testing is the standard, the accidents will continue.
A simple test
I first gave this test some 25 years ago, and have given similar tests over the years at club meetings, CFI classes, and similar to prove the point that pilots do not know the simplest essential facts.
The questions were designed to be as simple as possible, subject matter that was un-arguable, subjects and answers everyone should know. You can, and should make up your own test questions and present them to your club members.
Here are a few:
Why does an aircraft have a rudder? What is “angle of attack?” What turns a glider? What causes a glider to be stable in pitch?
Try it with your own group, and you will discover few can correctly answer even the most basic questions.
These and many other questions (and answers) are included in my popular (English language) first flight-training textbook, “Glider Basics From First Flight To Solo.”
More tests are included in my “Glider Flight Instructor Manual” including the pre-solo test.
As an instructor, and especially as a flight school, it is our responsibility to ensure we comply with the Federal Regulations. One way we prove this is with a series of written tests each student takes during training. We can prove students knew the information at one time during their training. As a matter of discipline, we will not accept anything other than absolutely correct answers.
As an instructor or student pilot, you should know the answers to these questions without hesitation. If not, you need to dig into the textbooks for the answers to these and many other facts.
I have stated many times, the only reason I am alive today is because of a wonderful individual who became a close friend many years ago, Wolfgang Langewiesche, who wrote the seminal book, Stick And Rudder, in 1944. Everything I know about how an aircraft works stems from this book.
Every pilot needs to develop a small library of texts to be a competent, safe, pilot. If you purchased everything ever written on the subject, it wouldn’t occupy a single shelf. Without this knowledge, you are a hazard to yourself and everyone else.
If you are a CFI, you should know how people learn. Fully 80% of all knowledge comes through the sense of sight, while only 13% comes though hearing. It is only a small stretch to state if you tell a student some fact, they only have a 13% chance to remember, while if they read it or visualize in some other way, they will have a better chance of remembering over a much longer period of time.
The basic problem
So, there is a demonstrable, fundamental lack of knowledge, which makes glider pilots particularly susceptible to accidents. This lack of knowledge stems from a societal problem created by intelligent people who are willing to accept minimal training while learning a dangerous activity, accompanied by poorly trained, uneducated instructors.
The instructors are allowed to become instructors and to maintain their instructor ratings by an equally uneducated government bureaucracy (the FAA.) Ultimately, the FAA is responsible for failing to maintain even minimal standards, so the entire teaching system breaks down. Few FAA inspectors who have the responsibility to issue original CFI ratings have even minimal training in gliders. The FAA examiners loosely supervise designated Pilot Examiners, so the ignorant are supervising the ignorant – thus creating a circle of sustained ignorance.
The problem is further exacerbated by instructors and pilot candidates who seek out the worst of the examiners (otherwise known as “Santa Claus examiners”) to present easy flight tests that fails to test to the implied standard. The result is self-generated, persistent ignorance. This ignorance generates new CFIs who learn to this low standard and then teach not only to this low standard, but also due to forgetting, generates a new group of pilots who are even less knowledgeable than the prior generation.
Many accidents begin with improper assembly and improper preflight inspections. It is not my intent to review how to perform an assembly or preflight inspection. You will find this information in several well-written textbooks by recognized experts.
There are common endemic errors you will observe by almost every pilot performing these simple tasks. The most common is failure to use a written checklist as prescribed by the FAA. Without a written checklist, the pilot performs the assembly, preflight and pre-takeoff checklists in a haphazard, incomplete manner. The result is numerous accidents traceable to this simple, easy, life-saving practice.
Sidebar: Several years ago, I was invited to an international CFI conference in Sweden. Twenty-two countries were represented. The purpose of the conference was to standardize flight-training practices. These conferences are held every other year or so, but the SSA has traditionally not publicized them so few USA instructors are aware of the benefits they could derive from such conferences.
The result of this conference was with very few minor differences, we all agreed. Those of us who are recognized as the most experienced, basically agreed on all manner of flight training practices and procedures.
So, the common practice of assembling a glider, performing a preflight inspection and pre-takeoff checklist with the use of written checklists can result in safer flying. Without CFI supervision and insistence, pilots will continue to have easily preventable accidents.
Here is one idea you may want to carefully use in your training program.
There are few emergencies we can simulate without undue risk. In our school, every pilot receives a minimum of three rope breaks – one straight ahead, two at 200 feet (aerotow only.) We also perform a too-low power launch where the tow pilot accelerates to a speed that allows the glider to takeoff, but the tow plane never leaves the ground.
So far, no one (no one!) has recognized there is a problem and released. If this was a real scenario, the tow plane might have run off the end of the runway with the glider still on tow!
The lesson is valid. Fatal accidents have occurred when there was something wrong with the glider (tailplane installed improperly) and the glider rolled along the ground for more than 3,000 feet before crashing, killing the pilot.
The towpilot and glider instructor must be extremely careful to not allow the training situation to get out of hand.
Stalls & Myths
It’s fun to do. I was standing in front of an audience of 250 flight instructors and said, “You can all finish this statement: “An aircraft can be stalled at any ________ and any _________.”
In one voice, they recant the axiom printed in every training manual. The FAA endorses it as well as AOPA and every instructor and pilot. It has been drummed into us from the beginning of our flight training in the hope we will somehow be safer pilots by simply knowing this one “fact.”
You filled in the blanks just as every pilot does.
“An aircraft can be stalled at any airspeed and any attitude.”
More pilots know this one “fact” than any other.
And, it is not true!
Further, it is great fun to demonstrate it is not true.
You and I will take a glider up and I will pick the attitude and airspeed. You are expecting some goofy, weird, never-to-be-seen-again, strange attitude/airspeed combination. But no. I tell you to fly 60 knots, wings level, with the nose below the horizon.
Now stall the aircraft at this attitude and airspeed.
There is always a delay. I wait for a response. Some pilots will start to pull the stick back. The attitude changes, violating the premise.
The well known “fact” is wrong.
In fact, if you simply keep the nose of the glider below the horizon at a reasonable attitude, the glider cannot be stalled!
OK, somebody always brings up some kind of violent turbulence, but we don’t fly in these extreme conditions.
Bingo! The end of stall accidents. Emphasize the importance of a proper, nose below the horizon attitude at all times, but especially in the landing pattern, and you have eliminated the so-called major problem causing more aviation deaths than any other factor.
A glider stalls easier in a steep bank than a shallow turn. Everyone knows this “fact.”
Most pilots even know the formula for the increase in stall speed vs. angle of bank/G forces. The stall speed goes up 41% in a 60-degree bank angle. A very high percentage of pilots know this “fact.”
You guessed it. It is not true. Try it.
If a wing, or both wings stall, there can only be two results. Either one wing stalls, causing a rolling motion, or both wings stall causing a pitching motion. (So far you all agree.)
The next time you fly your glider, roll into a bank of 45 degrees. (More is better.) Pull back on the stick and bring the nose of the glider well above the horizon. Hold the stick full back and watch what happens.
The glider does not roll. The nose does not pitch. What you see is the nose of the glider yawing through the horizon. (You really must try this.)
Why does it yaw? Before it reaches a stalling angle of attack, the speed reduces and the lift diminishes so there is not enough lift to hold the glider up. It falls . . . Sideways. And the relative airflow pressing against the side of the fuselage/tail causes the nose to yaw through the horizon long before the wing stalls.
Why is this important?
If the wing has not stalled, all of the controls work normally. Your instinctive reactions are correct. Applying opposite aileron to recover from the steep bank will result in the wings rolling level.
And, it does not have to be a very steep turn. Try it from a 30-degree bank. Try to aggravate the situation by applying full, abrupt opposite aileron. The glider rolls level.
There is one provision: This applies to normally type certificated gliders flying within weight and balance limitations. There may be exceptions such as the Puchaz, which should not have been certificated in the normal category. (A serious FAA mistake.)
(Power planes have the additional factor of torque and P-factor caused by the engine and propeller during power-on stalls beyond the scope of this article.)
Flight training must place special emphasis on flying an appropriate airspeed by monitoring pitch attitude. During the landing pattern or performing the 180 degree turn after a low level rope break, the pilot must be taught to assume, and monitor an appropriate pitch attitude at all times, and to plan and use a landing pattern that permits the safer, steeper angles of bank.
Accompany these two disciplines along with keeping the yaw string straight, and you have eliminated what has been declared to be the major contributor to fatal glider accidents, the stall/spin.
Accident statistics clearly show pitch attitude / airspeed control, and flying in a coordinated manner during any maneuver close to the ground is paramount to pilot safety. CFI’s should accept nothing other than superior performance and discipline from pilots they teach or give BFR’s to.
What the FAA means
The FAA states, “An aircraft can be stalled at any attitude and any airspeed.” This is obviously wrong, and wording should be, “An aircraft can be in a stalled condition at any attitude and any airspeed.”
This correction would state the facts as they really are and help pilots and CFIs understand and teach the simple flying skills needed to fly safely.
More about stalls.
What is the minimum stall speed of the glider you fly?
Most pilots will answer incorrectly, quoting the glider’s flight manual.
I don’t make this an issue with private glider candidates, but CFIs should know the answer is always the same. The minimum stall speed is always zero, which applies when the glider is experiencing zero G forces.
Push the nose down. Increase the speed slightly; pull back on the stick to raise the nose above the horizon, slow to a minimum airspeed, and then aggressively push forward to produce reduced Gs.
The glider travels ‘over the top’, at a low airspeed, with reduced G forces then, with the nose below the horizon, aggressively pull back on the stick and the glider stalls, with the nose below the horizon.
Granted, this takes a lot of maneuvering not normally experienced by most glider pilots, however, it is a scenario during ground launch (winch/car tow) emergencies, and less common on aggressive thermal entries.
The rope breaks with the glider in nose-high attitude. The glider pilot may attempt to gain or hold altitude with back stick pressure and the airspeed slows. The glider pilot then pushes forward on the stick to recover. When the nose lowers below the horizon, the pilot may aggressively pull back on the stick, creating a stall. If a turn is also initiated, to return to the landing pattern, a spin can result.
So this scenario is an exception to my statement that a glider cannot be stalled with the nose below the horizon, and must be covered during ground launch training. The premise of the nose below the horizon in a normal gliding attitude and airspeed being a prime stall preventing practice is still valid and must be emphasized (demanded) during training.
Another scenario where a pilot can cause a stall with the nose below the horizon, is on a high speed contest style finish with a steep pull-up to a low speed, followed by a push over to get the nose down, followed still by an aggressive back stick to prevent the nose from going down too far.
Preventing landing accidents.
If the accident statistics are correct, and most fatalities (75% quoted) are caused by stall/spins while landing, then we have solved the problem.
Using the premises stated, it is nearly impossible to stall a glider flying at an appropriate, stable, nose below the horizon, pitch attitude (airspeed.) If you must use the exceptions, add the words, “without violent control motions and excluding extreme turbulence.”
If you additionally include: Develop the discipline of keeping the yaw string straight, and using steeper bank angles during the turns in a landing pattern, you have practically eliminated the problem of stall/spins in the landing pattern.
A pilot who has developed the discipline of coordinated flight, stable, appropriate airspeed, and a proper landing pattern with steeper turns is extremely unlikely to be a victim of the dreaded stall-spin accident.
The instructor or pilot examiner who demands these disciplines will generate safe pilots. To accept anything less is unacceptable. From an instructor’s viewpoint it is not difficult to do. From the student pilot’s standpoint, as long as they know what the standard is, they will perform to that standard. If they are unable, or refuse to have the necessary knowledge or skills, they should not be permitted to proceed.
Few of you will disagree with the basic thesis that if pilots can be trained to fly at a proper, constant pitch attitude/airspeed coupled with a straight yaw string, (especially while landing) stalls are nearly impossible.
Flying with an appropriate pitch attitude, and monitoring the airspeed frequently, developing the skill of flying a constant, correct airspeed is paramount to safe flight.
When teaching people to fly, three general areas are covered: The Aircraft, The Pilot, and the Environment. Add “Situations” and you have an appropriate acronym when teaching some students. “APES”
Understanding how the aircraft operates, how we as human beings operate (very predictably) and how the environment affects our behavior, helps us fly better and safer.
Environment means not only the weather, but also the situational environment. Flying in a crowded thermal, is an environment. A winch launch is an environment, an off field landing is an environment.
As it applies to the most common of all glider fatality environments, the manner in which we fly landing patterns is an environment we need to discuss.
There are several common-practice landing patterns used in general aviation. Rectangular is the most common. It can consist of five legs, upwind, crosswind, downwind, base and final, (360 degree pattern) or any part of this list 270, 180, 90 degree pattern) finishing with a straight in approach.
Some aircraft have especially poor visibility straight ahead, so the aircraft carrier landing approach with a curved base leg is appropriate, and is used as a standard method by the Navy and others.
The circling approach is also a viable technique, where a pilot descends overhead in a spiral to the downwind leg.
For gliders, we need to teach and use a landing pattern that best prepares the pilot for the hazards of a potential off field landing. This is the full 360-degree pattern that gives us the best view of the landing area for hazards such as Slope, Length, Obstructions, & Wind. (SLOW)
As it applies to our discussion on preventing stalls during landings, we must investigate the three areas – plane, pilot, and environment and apply what we know to the landing pattern.
Teaching the landing process is performed to a strict discipline using predictable, standard events, spacing, descent rates and checklists. The methodology we use does not rely on key altitudes, or landmarks; instead on easy to learn and identify angles and the use of defined judgmental tools including relative sizes of familiar things, and depth perception.
My recent article, printed in many magazines around the world, titled, “How Far Can You Spit?” explains how people learn and remember angles very easily and this tool can be used to teach pilots to land safely in a strange environment (off field landings.) A copy of this article can be found on our web site: www.eglider.org.
If you look at landing fatalities, the investigators often blame the stall/spin. My theory is that few of these are really stall/spins.
The most common error.
One of the most common errors shared by most glider pilots, is flying the downwind leg too close to the landing area. You will see this on any soaring day at your local gliderport.
The result is a base leg that is too short, with many pilots simply performing a 180 degree turn from downwind to final with no base leg at all or perhaps a very brief one.
If we had some way to inspect a landing pattern before the “stall/spin” accident, I believe we would reveal this common piloting error. (Data loggers now make this possible in some cases.)
The Foxhole Syndrome
Soldiers in a WWII foxhole during a bombardment commonly think of being at home. Pilots under the stress of an off-field, or low altitude landing, also exhibit the foxhole syndrome by flying too close to “home,” and thus fly too close to the landing area during the downwind leg.
In addition, they are often lower than desired because they delayed the inevitable.
So, you will see for yourself at your local gliderport, a pilot who is lower than desired will also be closer than desired on the downwind leg.
This results in not being able to perform the extremely important base leg.
A pilot who flies the landing pattern too low and too slow will turn from the downwind leg lower than desired, and usually requires a steeper angle of bank than normally practiced by the pilot.
Interestingly, the pilot still wants to land near the end of the runway where landings are normally made, but to do this, a lot of dive brakes are required during the resulting 180 degree turn from downwind to final, so the glider is found in a turn, with lots of dive brakes at low altitude.
In this scenario, the final culprit can be wind gradient or turbulence or perhaps (probably) the pilot is flying uncoordinated, but the glider simply is falling – not stalling- out of the sky.
I’m not sure I am making myself clear, but the culprit is not the stall, but a landing pattern that is too close and too low, requiring a steep turn to get lined up with the landing area.
There is the well known psychological problem associated with low altitude turns of the pilot attempting to hold the glider up with back stick pressure, but the angle of bank is steep enough that the glider simply falls out of the sky, long before a stall/spin can occur.
The recovery process is simple enough. Since the glider is not stalled, the controls work normally. Applying opposite aileron would cause the glider to recover from the steep turn, but to do so would direct the glider in the wrong direction, so the pilot continues using inappropriate control forces until the inevitable occurs.
I contend the primary problem relating to “stall/spin” accidents is not the stall/spin, but a landing pattern flown too close and too low, and gliders therefore more commonly fall rather than stall.
The answer is to teach pilots methods to fly proper spacing, proper airspeeds, proper coordination, and to have a plan of action when things are not proceeding correctly while flying the landing pattern.
The Base leg.
As it turns out, the base leg is extremely important for safe landings, especially in a strange environment such as an off-field landing.
With an appropriately planned base leg, the pilot makes the turn from downwind to base, and during this turn, looks back to the intended touchdown point to make a judgment about how the resulting glide angle looks.
Too high? Simply turn away from the landing area with the dive brakes deployed to essentially extend the downwind leg.
Too low? Abbreviate the base leg and turn towards the landing area with the dive brakes closed.
Flying the downwind leg too close to the landing area eliminates the possibility of these adjustments without excessive (dangerous) maneuvering.
We have been teaching glider pilots to fly safely for more than 40 years, and I believe our attention to this one pilot skill or perhaps set of pilot skills has been the major contributor to our outstanding safety record.
The 45-degree base leg method
A “new” landing pattern has recently been proposed because of a perceived problem a pilot might have while flying the downwind leg. In many gliders, the intended touchdown area disappears under the wing as the glider passes by. We solved this “problem” with a maneuver commonly called a “wing dip.” Dip the wing and take a peak.
I happened to be there when the idea was first proposed and recognized the problem with the 45-degree base leg immediately. I’m surprised how many have embraced this idea.
The 45-degree base leg technique, like any other technique, probably works fine under “normal” conditions and when the pilot flies the prescribed landing pattern. The problem occurs when the pilot is too close on the downwind leg, which predictably occurs whenever the pilot is under stress such as an off field landing, or enters the landing pattern low.
Beginning on the downwind leg, too close to the landing area, the pilot then performs the 45 degree turn which results in no base leg whatsoever, followed by a steep, acute, low altitude 135 degree turn (probably the dangerous button-hook turn) onto the final leg.
I don’t need to tell you how fraught with risk this maneuver has. But, like any other landing pattern gone wrong, it is exactly what will occur when you consider the way we humans behave under stress.
I remember suggesting if you want to cut off the corner of the 90-degree turn onto base leg, (for better visibility of the landing area) then why not two 45-degree turns? Or better yet, four 22.5-degree turns? Keep making more and more small turns and you have re-discovered the 180-degree turn of the Navy aircraft carrier landing.
As I watch visiting pilots fly their version of whatever landing pattern, I am not concerned as long as the spacing/distance is good, airspeed/pitch attitude is appropriate, and the turns are made in a coordinated manner.
CIF’s must demand a disciplined landing pattern, in the hopes that someday, when the pilot is making an off field landing in unfriendly terrain, the glider is flown in a controlled manner. If you don’t fall, or stall, you probably will survive.
Keeping with the myth theme, it is a myth to believe undershooting is a major problem. It is estimated some 80% of off field landing accidents are overshoot.
It is a myth to believe undershooting is more dangerous than overshooting as overshooting also results in a high-speed crash (trying to force the glider down with the elevator.)
You will see it at your gliderport every flying day. In our case after more than 30 years, we have had two landings short of our runway, and thousands of landings well past the intended touchdown zone into the second half of the runway.
Those of you who are not familiar with the TLAR (That Looks About Right) how to teach landings technique, will find it in my popular flight training manuals, “Glider Basics From First Flight To Solo,” “After Solo” and the “Glider Flight Instructor’s Manual.”