Glider Flying

Risk Management

Risk management, a formalized way of dealing with hazards, is the logical process of weighing the potential costs of risks against the possible benefits of allowing those risks to stand uncontrolled. In order to better understand risk management, the terms “hazard” and “risk” needs to be understood.

Hazard identification is a process used to identify all possible situations where people may be exposed to injury, illness, or disease. Typical hazards are weather, mountains, obstacles, and operational and equipment failure.

Risk is the chance of a hazard actually causing damage and/or injury. Risk is measured in terms of consequences and likelihood. Risk management is the overall process of risk identification, risk analysis, control of risks, and risk evaluation. Risk control is part of risk management that involves the implementation of policies, standards, procedures, and physical changes to eliminate or minimize adverse risks. For example, the pilot understands the risk of a tow line break during launch. An acceptable risk that he or she can mitigate by understanding the risk and having a plan of actions to follow after a tow line breaks.

Safety Management System (SMS)

The Safety Management System (SMS) is a formal, top-down business approach to managing safety risk, which includes a systemic approach to managing safety, including the necessary organizational structures, accountabilities, policies and procedures. SMS is becoming a worldwide standard throughout the aviation industry integrating risk management, occupational safety, health, security, environment, and other concepts for the management of a complete safety program. SMS is a comprehensive program designed for a formal organization. The individual pilot can learn from the process and apply the concept for his or her own personal safety considerations, such as:

Risk management decision-making.
Management capabilities before a system failure
Risk controls through safety assurance
Knowledge sharing between regulations and the pilot
Promoting a safety framework by having a sound safety culture or attitude

Aeronautical Decision-Making (ADM)

Aeronautical decision-making (ADM) is a mental process used by pilots (systematically) to determine a course of action in response to a given set of circumstances.

Circumstance: My oxygen system has a slow leak. Soaring conditions are prefect and I do not need oxygen for today.
Circumstance: High winds are forecast later today, but I should return before the wind changes.
Circumstance: My batteries are low, but I am only planning a short flight.

Learning effective ADM skills cannot be overemphasized. As advancement in training methods, airplane equipment and systems, and services continue for pilots, incidents and accidents still occur. Despite all the changes in technology to improve flight safety, the human factor is the same. The human factor is still involved in a high percent of all aviation accidents.

Circumstances as mundane as a “slow oxygen leak,” a “high wind forecast,” or “low batteries” are parts of a decision chain leading to an incident or accident. The term “pilot error” has been used to describe the causes of these accidents meaning that an action or decision made by the pilot was the cause or a contributing factor that led to the accident. In the previous circumstances, the chain is broken if the pilot—has the “slow oxygen leak” repaired—respects the “high wind forecast” and delays the flight—charges the “low batteries” before the next flight. The pilot error definition also includes the pilot’s failure to make a decision or take action. Human factor-related accidents are accidents that did not involve a single decision but a chain of decision and factors leading to the accident. A “poor judgment chain,” referred to as the error chain, describe the concept of contributing factors in a human factors-related accident. Breaking one link in the chain normally is all that is necessary to change the outcome of the sequence of events.

Advisory Circular (AC) 60-22, “Aeronautical Decision Making,” provides introductory material, background information, and reference material on ADM. The material in this AC provides a systematic approach to risk assessment and stress management in aviation, illustrates how personal attitudes can influence decision-making, and how those attitudes can be modified to enhance safety in the cockpit. This AC also provides instructors with methods for teaching ADM techniques and skills in conjunction with conventional flight instruction.

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Transponder Code

Filed Under: Human Factors - Gliders

The Federal Aviation Administration (FAA) has assigned transponder code 1202 for use by gliders not in contact with an air traffic control (ATC) facility with an effective date of March 7, 2012. The notice was published in JO 7110.577, a copy of which is available on the FAA website at www.faa.gov. Gliders operating in areas where there is an agreement with local ATC to use a different code should contact the agreement sponsor for guidance on which code to use.

Definitions

SQUAWK: The 4-digit code set in the transponder, such as 1202.
IDENT or SQUAWK IDENT: A controller may ask you to “ident” or “squawk ident” to verify your location on the radar screen. Do NOT push the ident button unless they ask you to. When asked, push the button on the transponder marked IDENT. This causes the target on the controllers radar screen to change, identifying your transponder location.
Tow planes are to Squawk 1200, as normal.

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Cockpit Management

Filed Under: Human Factors - Gliders

Prior to launch, passengers should be briefed on the use of safety belts, shoulder harnesses, and emergency procedures. If ballast is used, it must be properly secured. Organize the cockpit so items needed in flight are accessible. All other items must be securely stowed. The necessary charts and cross-country aids should be stowed within easy reach of the pilot.

Personal Equipment

If a parachute of the approved type is to be available for emergencies, Title 14 of the Code of Federal Regulations (14 CFR) part 91 requires that a certificated and appropriately rated parachute rigger repack it within the preceding 180 days if it is made of nylon. The packing date information is usually found on a card contained in a small pocket on the body of the parachute.

Oxygen System

14 CFR part 91 also requires that the pilot in command (PIC) use supplemental oxygen for flights more than 30 minutes in duration above 12,500 feet and at all times during a flight above 14,000 feet. If supplemental oxygen is used, the system should be checked for flow, availability, and the PRICE checklist should be used:

P = Pressure
R = Regulator
I = Indicator
C = Connections
E = Emergency bail-out bottle

The importance of understanding the need for oxygen equipment in gliders has been heightened in recent years by a considerable increase in the number of high-altitude soaring flights. The exploration of mountain waves has led to numerous flights at altitudes in excess of 30,000 feet with several record flights in excess of 40,000 feet. In some parts of the country, it is frequently possible to soar to a 16,000- to 18,000-foot cloud base in thermals. In almost all parts of the United States such altitudes are attainable in cumulonimbus clouds.

At 18,000 feet, air density is only one-half that at sea level. The purpose of breathing is to supply oxygen to the blood and remove carbon dioxide. In each breath at 18,000 feet, the pilot breathes in only half as much oxygen as at sea level. This is not enough to deliver an adequate supply of oxygen to the blood, and the situation worsens as altitude increases. The automatic reaction is to breathe twice as fast. This hyperventilation, or overbreathing, is almost worse than going up without oxygen in the first place because it results in eliminating too much carbon dioxide from the blood. The immediate effects of hyperventilation are:

Spots before the eyes
Dizzy feeling
Numbing of fingers and toes, followed by possible unconsciousness

The dangers of oxygen deprivation should not be taken lightly. At around 20,000 feet MSL, pilots might have only 10 minutes of “useful consciousness.” By 30,000 feet MSL, the time frame for “useful consciousness” decreases to 1 minute or less. For planned flights above 25,000 feet MSL, an emergency oxygen backup or bailout bottle should be carried.

The U.S. Air Force in cooperation with the Federal Aviation Administration (FAA) provides a 1-day, high-altitude orientation and chamber ride for civilian pilots. The experience is invaluable for any pilot contemplating high-altitude soaring and is even required by many clubs and operations as a prerequisite.

Aviation Oxygen Systems

Aviation oxygen systems are designed for airborne aviation applications. Unlike a medical-type oxygen system, an aviation system is generally much lighter, compact, and calibrated to deliver oxygen based on extensive research in human flight physiology. Prior to purchasing any type of oxygen system, pilots should research the different options and choose an oxygen system that is appropriate for the type of flying that they do because there are many manufacturers and types of system available. Two common types of systems used today are the Continuous-Flow System and the Electronic Pulse Demand Oxygen System (EDS).

Figure 13-9. Continuous-flow oxygen system.

Continuous-Flow System

The continuous-flow system uses a high-pressure storage tank and a pressure-reducing regulating valve that reduces the pressure in the cylinder to approximately atmospheric pressure at the mask. [Figure 13-9] The oxygen flow is continuous as long as the system is turned on. In some installations, it is possible to adjust the amount of oxygen flow manually for low, intermediate, and high altitudes; automatic regulators adjust the oxygen flow by means of a bellows, which varies the flow according to altitude. When using the continuous-flow oxygen system, the pilot can use either an oxygen mask or a nasal cannula. [Figures 13-10 and 13-11]

Electronic Pulse Demand Oxygen System (EDS)

The EDS is the lightest, smallest, and most capable on-demand oxygen system available that delivers altitude-compensated pulses of oxygen only as you inhale, using as little as 1⁄8, typically 1⁄6 the amount of oxygen at 1⁄4 the weight and volume over conventional constant-flow systems that deliver one liter per minute per 10,000 feet. [Figure 13-12] The EDS has a precision micro-electronic pressure altitude barometer that automatically determines the volume for each oxygen pulse up to pressure altitudes of 32,000 feet and higher altitudes are compensated with pulses of greater volume. The EDS automatically goes to a 100 percent pulse-demand mode at pressure altitudes above 32,000 feet.

The EDS can be set to one of three D (day or delayed) modes and delays, responding with oxygen until it senses pressure altitudes of approximately 5,000 or 10,000 feet, conserving oxygen when it is not needed. It can also be set to N (night or now) mode for night flying where it responds from sea-level and up. Both modes provide the same amount of oxygen, automatically tracking pressure altitude changes. The EDS limits its response to a maximum respiration rate of about 20 breaths per minute, virtually eliminating hyperventilation usually encountered in stressful situations. There are no scales to observe or knobs to turn as you climb or descend. Adjusting (zeroing) for new barometric pressures is not needed because the EDS responds directly to pressure altitude, as do the physiological properties of your body.

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Human and Physiological Factors that Affect Flight

Filed Under: Human Factors - Gliders

Fatigue

Fatigue is a major human factor that has contributed to many maintenance errors resulting in accidents. Fatigue can be mental or physical in nature. Emotional fatigue also exists and effects mental and physical performance. A person is said to be fatigued when a reduction or impairment in any of the following occurs: cognitive ability, decision-making, reaction time, coordination, speed, strength, and balance. Fatigue reduces alertness and often reduces a person’s ability to focus and hold attention on the task being performed. [Figure 13-4]

Symptoms of fatigue may also include short-term memory problems, channeled concentration on unimportant issues while neglecting other factors that may be more important, and failure to maintain a situational overview. A fatigued person may be easily distracted or may be nearly impossible to distract. He or she may experience abnormal mood swings. Fatigue results in an increase in mistakes, poor judgment, and poor decisions or perhaps no decisions at all. A fatigued person may also lower his or her standards.

Tiredness is a symptom of fatigue. However, sometimes a fatigued person may feel wide awake and engaged in a task. The primary cause of fatigue is a lack of sleep. Good restful sleep free from drugs or alcohol is a human necessity to prevent fatigue. Fatigue can also be caused by stress and by overworking. A person’s mental and physical state also naturally cycles through various levels of performance each day. Variables such as body temperature, blood pressure, heart rate, blood chemistry, alertness, and attention rise and fall in a pattern daily. This is known as one’s circadian rhythm. [Figure 13-5] A person’s ability to work (and rest) rises and falls during this cycle. Performance counter to circadian rhythm can be difficult. Until it becomes extreme, a person may be unaware that he or she is fatigued. It is easier recognized by another person or in the results of tasks being performed. Flying alone when fatigued is particularly dangerous.

Figure 13-5. Many human variables rise and fall daily due to one’s natural circadian rhythm.

The best remedy for fatigue is to get enough sleep on a regular basis. Pilots must be aware of the amount and quality of sleep obtained. Countermeasures to fatigue are often used. Effectiveness can be short lived and many countermeasures may make fatigue worse. Caffeine is a common fatigue countermeasure. Pseudoephedrine found in sinus medicine and amphetamines are also used. While effective for short periods, a fatigued person remains fatigued and may have trouble getting the rest needed once they try to sleep.

If you find yourself suffering from acute fatigue, stay on the ground. Glider pilots often become fatigued while flying due to soaring in close proximity to other gliders in areas of lift or because of the constant requirement to see and avoid other traffic. Getting adequate rest is the only way to prevent fatigue from occurring. You should avoid flying when you have not had a full night’s rest, when you have been working excessive hours, or have had an especially exhausting or stressful day. If you suspect you are suffering from chronic fatigue, consult your doctor.

Hyperventilation

Hyperventilation occurs when you are experiencing emotional stress, fright, or pain, and your breathing rate and depth increase, although the carbon dioxide is already at a reduced level in the blood. This can happen to both the experienced and novice pilot. Hyperventilation causes an excessive loss of carbon dioxide from your body, which can lead to unconsciousness due to the respiratory system’s overriding mechanism to regain control of breathing.

Glider pilots who encounter extreme or unexpected turbulence or strong areas of sink over rough terrain or water may unconsciously increase their breathing rate. When flying at higher altitudes, either with or without oxygen, a tendency to breathe more rapidly than normal may occur, which can lead to hyperventilation.

It is important to know the symptoms of hyperventilation and correctly treat for it. [Figure 13-6] Treatment for hyperventilation involves restoring the proper carbon dioxide level back in the body. Breathing normally is both the best prevention and the best cure for hyperventilation. In addition to slowing the breathing rate, you also can breathe into a paper bag or talk aloud to over-come hyperventilation. Recovery is usually rapid once the breathing rate is returned to normal.

Figure 13-6. Common symptoms of hyperventilation.

Inner Ear Discomfort

Gliders are not pressurized, therefore, pressure changes can affect glider pilots that are flying at high altitudes. Inner ear pain and a temporary reduction in ability to hear are caused by the ascents and descents of the glider. The physiological explanation for this discomfort is a difference between the pressure of the air outside the body and the air inside the middle ear. The middle ear cavity is small and located in the bone of the skull. While the external ear canal is always at the same pressure as the outside air, the pressure in the middle ear often changes more slowly. Even a slight difference between external pressure and middle ear pressure can cause discomfort.

When a glider ascends, middle ear air pressure may exceed the pressure of the air in the external ear canal, causing the eardrum to bulge outward. This pressure change becomes apparent when you experience alternate sensations of “fullness” and “clearing.” During a descent, the reverse happens. While the pressure of the air in the external ear canal increases, the middle ear cavity, which equalized with the lower pressure at altitude, is at lower pressure than the external ear canal. The result is higher outside pressure, causing the eardrum to bulge inward.

This condition can be more difficult to relieve due to the fact that air must be introduced into the middle ear through the eustachian tube to equalize the pressure. The inner ear is a partial vacuum and tends to constrict the walls of the eustachian tube. To correct this often painful condition, which causes temporary reduction in hearing sensitivity, pinch your nostrils, close your mouth and lips, and blow slowly and gently in the mouth and nose. This procedure, called the valsalva maneuver, forces air up the eustachian tube into the middle ear.

Spatial Disorientation

For glider pilots, prevention is the best remedy for spatial disorientation. If the glider you are flying is not equipped for instrument flight, and you do not have many hours of training in controlling the glider by reference to instruments, it is best to avoid flight in reduced visibility or at night when the horizon is not visible. Susceptibility to disorienting illusions can be reduced through training, awareness, and learning to rely totally on your flight instruments. [Figure 13-7]

Figure 13-7. Learning to rely totally on flight instruments to fly will reduce the likelihood of experiencing a disorienting illusion while in flight.

Dehydration

Dehydration is the term given to a critical loss of water from the body. The first noticeable effect of dehydration is fatigue, which in turn makes top physical and mental performance difficult, if not impossible. Glider pilots often fly for a long period of time in hot summer temperatures or at high altitudes. This makes dehydration very likely for two reasons: the gliders clear canopy offers no protection from the sun and, at high altitudes, there are fewer air pollutants to diffuse the sun’s rays. The result is continual exposure to heat that the body attempts to regulate by perspiration. If this fluid is not replaced, fatigue progresses to dizziness, weakness, nausea, tingling of hands and feet, abdominal cramps, and extreme thirst. [Figure 13-8]

Water should be taken on every flight to prevent dehydration. The effects of dehydration on a pilot’s performance are subtle, but can be dangerous and are especially a factor in warmer climates. Some glider pilots wear a hat to block the sun from distracting their ability to fly and see the instruments. Pilots should ensure that the brim of the hat is not too large, which can interfere with the ability to scan for other gliders and air traffic.

Heatstroke

Heatstroke is a condition caused by any inability of the body to control its temperature. Onset of this condition may be recognized by the symptoms of dehydration, but also has been known to be recognized only by complete collapse. To prevent these symptoms, it is recommended that you carry an ample supply of water and use it at frequent intervals on any long flight, whether you are thirsty or not. Wearing light colored, porous clothing and a hat provides protection from the sun. It is also helpful to keep the cockpit well ventilated, which aids in dispelling excess heat.

Cold Weather

When flying at higher altitudes, the inside of the glider can get cold. Proper clothing is a must since temperatures of –30° to –60 °C may be encountered at altitude. Proper preparation for the cold is especially difficult since temperatures on the ground are often pleasant on wave soaring days. Sunshine through the canopy keeps the upper body amazingly warm for a time, but shaded legs and feet quickly become cold. Frostbite is a very real threat. After an hour or two at such temperatures, even the upper body can become quite cold. Layered, loose-fitting clothing helps insulate body heat. Either wool gloves or light, fitted gloves with mittens over them work best for the hands. Mittens make tasks such as turning radio knobs difficult. For the feet, two or three pairs of socks (inner, silk; outer, wool) with an insulated boot are recommended.

In addition, the low temperatures can cause two other symptoms: it frosts your exhaled breath on the inside of the canopy and it causes the kidneys to excrete liquid at an accelerated rate.

A clean piece of cloth (that will not damage the canopy) can be used to wipe the condensation or frost from the canopy, if needed, but the best way to clear the canopy is a little fresh air through the side or front vent to help delay the buildup of frost. Unfortunately, this also quickly lowers the inside temperature, so it is best to wear clothing in layers so that you can easily take off or put on what is needed. There is little that can be done for the kidneys excreting liquid at an accelerated rate. The best course of action is to plan for it in advance by making a bathroom stop before you take off. Remember that the body is dehydrating more rapidly because of the cold and always be looking for signs of dehydration.

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Learning from Past Mistakes

Filed Under: Human Factors - Gliders

The National Transportation Safety Board (NTSB) generates accident reports any time a reportable glider accident occurs. This information is open to the public and can be found at www.ntsb.gov/ntsb. Once on the accident query page, enter the term “glider,” which retrieves all reports pertaining to gliders to include tow plane accidents. It is important for pilots to review NTSB accident reports and learn what the common errors and hazards are that apply to glider operations. Learning from others mistakes helps reduce future accident rates.

An NTSB query from November 1, 2010, through October 31, 2011, shows 27 glider accidents. Shown in Figure 13-2 are some of the accidents reported during that time to include the type of aircraft, injuries, and the probable cause of the accident (if given).

Figure 13-2. Some accidents reported by the National Transportation Safety Board (NTSB) from November 1, 2011 through October 31, 2012.

Recognizing Hazardous Attitudes

It is important that pilots ensure their flight is safe by following procedures and checklists rather than hope for a safe flight and doing things they know are not right. As technological advances have contributed to fewer mechanical failures, which in turn has created a much safer air space, human error remains a constant factor in aviation accidents. There is a wealth of information available that focuses on unsafe behaviors and attitudes. For the purpose of this chapter, three common behaviors are addressed: complacency, indiscipline, and overconfidence. While complacency, indiscipline, and overconfidence share a common theme (each stem from experience), it is necessary to further delineate on the contributions of attitude-behavior linkage. To do so, we must further explore each term respectively.

Complacency

Often glider operations can seem less stressful than other modes of flight for no other reason than the “meditative silence” that accompanies gliding through the air. This is why complacency can easily materialize. Complacency is when a person has a sense of security about one’s surrounding yet fails to recognize or lacks awareness of possible danger. As pilots accrue flight time, their experience increases and, while one might view this as positive, their experience complacency may emerge. All too often, with experience comes boredom, a desire to cut corners, distractibility, feelings of content, minimal performance, and intentionally overlooking basic safety precautions (i.e., “I’ve done this a million times, it is not necessary to follow a checklist.”).

A few countermeasures include:

Never assume all facets related to the flight will go smoothly.
Always prepare and expect the unexpected.
Play the “what if” game and offer solutions to the scenarios you create.

The key to preventing complacency is keeping your mind sharp at all times by “being proactive rather than reactive.”

Indiscipline

Much like complacency, as pilots gain experience the failure to comply with certain standards seem to be evident in many aviation accidents. Either they feel their experience has taught them an easier or faster way to do certain tasks, or their attitude is not in alignment with the guidelines set forth by more experienced aviators. Nevertheless, indiscipline can be a very dangerous attitude that can easily lead to unsafe behaviors.

Overconfidence

Similarly to complacency, familiar circumstances or repetition can lead to a state of overconfidence. Developing and maintaining a sense of confidence toward your abilities is acceptable unless it leads to cutting corners and ignoring proper procedure.

Human Error

Human error is defined as a human action with unintended consequences. There is nothing inherently wrong or troublesome with error itself, but when you couple error with aviation and the negative consequences that it produces it becomes extremely troublesome. Training, flight examinations (written or oral), and operational checks should not be restricted to attempt to avoid errors but rather to make them visible and identify them before they produce damaging and regrettable consequences. Simply put, human error is not avoidable but it is manageable. [Figure 13-3]

Types of Errors

Unintentional

An unintentional error is an unintentional wandering or deviation from accuracy. This can include an error in your action (a slip), opinion, or judgment caused by poor reasoning, carelessness or insufficient knowledge (a mistake). For example, a pilot reads the glider performance numbers from the Pilot’s Operating Handbook (POH) and unintentionally transposed the number 62 to 26. He or she did not mean to make that error but unknowingly and unintentionally did.

Intentional

In aviation, an intentional error should really be considered a flight violation. If someone knowingly or intentionally chooses to do something wrong, it is a violation, which means that one has deviated from safe practices, procedures, standards, or regulations.

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Glider Tow Emergencies

Filed Under: Glider Towing

Takeoff Emergencies

The key to ensuring successful emergency management is the development of an emergency plan. Prior to takeoff, an emergency release point should be selected somewhere along the takeoff runway. This release point should leave sufficient room to land straight ahead, using normal stopping techniques, in the event conditions are such that a safe takeoff with the glider in tow cannot be completed.

During the initial climb out, the pilot of the glider will be noting certain altitudes that correspond to actions he or she will take in the event of a low-altitude emergency.

Tow Plane Power Failure on the Runway During Takeoff Roll

The following actions should be taken in the event the tow plane has a power failure on the runway during the takeoff roll:

The glider should release or be released by the tow plane and, if possible, maneuver right of the runway.
The tow plane should maneuver to the left of the runway if space is available. (Realize each individual airfield layout and obstacles may dictate an alternate procedure, so take the time to plan your actions prior to takeoff.)
Survey the abort area carefully and know where you can exit the runway (grass or taxi-way) without causing a hazard. Always have a plan.
Realize the glider will probably be airborne, therefore try and give the glider as much space as possible to land on the remaining runway and brake to a stop.
Know the stopping characteristics of the glider you are towing. Some models have very effective brakes, others do not.

Glider Releases During Takeoff With Tow Plane Operation Normal

The pilot of the tow plane should continue the takeoff eliminating a collision hazard with the glider.

Tow Plane Power Failure or Tow Rope Break After Takeoff but Below 200 Feet Above Ground Level

The pilot of the glider will normally release and descend straight ahead or maneuver using slight turns to make a specific forced landing. Because of airport obstructions in close proximity to the airport, the options available for a tow plane or glider land out may be limited. Discuss these options during the pilot briefing or safety meetings. Again, a plan will go a long way in ensuring a successful land out as a result of a takeoff emergency.

Tow Plane Power Failure or Tow Rope Break After Takeoff Above 200 Feet

The glider can more than likely return to the field in the event of engine failure or rope break. Since the tow plane requires considerably more altitude to return to the field in the event of a power failure, the pilot should have a specific plan in mind that includes pre-selected landing areas for each runway.

Glider Climbs Excessively High During Takeoff

The tail of the tow plane may be lifted if the glider climbs excessively high during takeoff. Should this happen, the application of full-up elevator on the tow plane may not be sufficient to prevent an accident. The tow pilot must be ready to pull the release handle in order to regain control of the tow plane. As a rule of thumb, use of a 200-foot tow line would require the glider to climb to over 20 feet above the altitude of the tow plane to present a danger of upset.

If at any time the nose of the tow plane is pulled uncontrollably by the glider to a dangerously high or low pitch attitude— PULL THE RELEASE.

If a Schweizer tow hitch is being used, it may be possible for the release mechanism to become jammed due to the excessively high position of the glider.

Airborne Emergencies

Glider Release Failure

If the pilot of the glider is unable to release, the tow pilot should be informed by means of the aircraft radio or by the following airborne signal. The glider will move out to the left side of the towplane and rock its wings. [Figure 12-17] Be sure not to mistake the wing rock as the beginning of a normal release. Wait a few seconds to ensure the glider’s wings are rocking. Once the tow pilot has determined the glider cannot release the tow plane should return to the airfield and release the glider at a safe altitude over the field.

Neither the Tow Plane or Glider Can Release

This is an extremely rare event. Although as improbable as this situation may be, you must be prepared. The pilot of the tow plane should inform the pilot of the glider by aircraft radio or airborne signal. The signal is accomplished by yawing the tail of the tow plane.

The glider should move to the low tow position. Then the tow plane should begin a slow descent toward an airfield of suitable length. Fly a wide pattern ending up on an extended final approach. Set up a very stabilized and gradual (200–300 foot per minute (fpm)) descent. Plan on landing long and allowing sufficient altitude while on short final for the glider to avoid approach obstacles.

Since the glider is lower than the tow plane, it lands first. The glider should not apply brakes until the tow plane has touched down. After touchdown, apply brakes gently or not at all, slowly coming to a stop. Remember, most glider brakes are not that effective, so allow the glider plenty of runway to stop.

While not well defined in soaring literature, some glider pilots are taught to attempt to break the tow rope rather than land behind the tow plane. If the glider does attempt to break the rope, maintain the tow plane in a straight and level attitude in an attempt to reduce the total gravity forces of the glider’s maneuver.

Glider Problem

You may notice the glider has a problem that is obviously not being detected by the glider pilot. The most common is the failure of the glider pilot to close and lock the glider’s spoilers/airbrakes prior to takeoff, resulting in an inadvertent undetected deployment of spoilers as the glider accelerates during takeoff. If you notice a problem with the glider, inform the glider pilot via radio and visual signal. The visual signal for “Glider Problem” is waggling the rudder while airborne.

Immediate Release

This situation requires immediate action by the pilot of the glider. Should the tow pilot rock the wings of the tow plane, the pilot of the glider must release immediately. Obviously, this would be appropriate during a time critical tow plane emergency, such as engine-failure or fire. [Figure 12-18]

Figure 12-18. The towplane is telling the glider to release immediately.

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Cross-Country Aerotow

Filed Under: Glider Towing

Planning is the key for a successful and safe cross-county tow. [Figure 12-15] Fuel consumption during any tow operation is high. Plan conservatively, using the maximum fuel consumption for your particular tow plane and also plan for the possibility of a diversion along your route of flight. Study your route of flight on current sectional charts paying particular attention to airspace, both controlled and special use.

Since a tow line break is a constant possibility, always plan your route of flight over landable terrain and, while in flight, strive to keep the glider over landable terrain. Tow and glider pilot fatigue is a real hazard. Make sure you are properly rested and in good medical condition prior to the flight. If the flight is particularly long, plan rest stops along the way, if feasible. Think about water requirements to keep hydrated and the inevitable physiological requirement. Use aircraft trim to ensure the maximum tow speed of the glider is not exceeded and to help reduce pilot fatigue.

Figure 12-16. On a cross-country tow, the tow pilot and glider pilot should have two way communication using portable radios.

Two-way communication between the glider and the tow plane is essential during cross-country tows. Ensure portable radios and glider batteries are fully charged prior to the flight and conduct a radio check as part of your pre-flight activities. [Figure 12-16]

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Tow Positions, Turns, Release, Descent, Approach and Landing

Filed Under: Glider Towing

Tow Positions, Turns, and Release

Glider Tow Positions

The high tow is normally used for glider tow operations. However, a low-tow position may be used in some instances, a cross-country tow for example. The main goal of both positions is to place the glider in a position that avoids the wake of the tow plane. [Figure 12-13]

Turns on Tow

All turns should be performed in a gentle and gradual manner. The pilot of the glider will attempt to fly the exact flightpath of the tow plane. To do this, the pilot points the nose of the glider at the outside wing tip of the tow plane during a turn.

Turns may be initiated upon reaching a safe altitude. Consideration should be given to obstruction clearance, terrain, and wind gradient. Turbulence and differential wing speed of the glider during turns are potential sources of problems.

Due to the length of the wingspan, the roll rate of a glider is typically slower than that of the tow plane. Consequently, the tow pilot should plan all turns with the understanding that the angle of bank determines the turn radius. Since the bank angles of the tow plane and glider must match to fly the same path, normally a maximum of 15–20° of bank is used.

Approaching a Thermal

When approaching a thermal, be vigilant of other gliders. Since the first glider in the thermal establishes the direction of turn, any glider joining the thermal is required to circle in the same direction as the first glider. This requires the tow pilot to position the flight in a manner that allows the glider proper and safe entry to the thermal. Be super alert when approaching thermals with circling gliders. Expect other gliders to be inbound to the thermal from all directions. Give the thermal traffic a wide berth. If the thermal appears to be especially crowded, steer clear of the activity.

Release

Standard glider release procedures are as follows [Figure 12-14]:

The pilot of the glider should ensure the tow line is relatively tight, with no excessive slack, prior to release. This allows the tow pilot to feel the release of the glider. If the tow rope is visible in the mirror, look for the wrinkle in the tow rope after the glider has released.
Once it has been confirmed that the glider has released and is clear, the tow pilot should clear the airspace to the left and start a medium bank, descending left turn.
The glider should turn right after release but may proceed straight ahead a few moments before turning right. Always be alert for non-standard maneuvering by the glider.

When the tow pilot has positively observed and confirmed the release of the tow line (assumption of release is not acceptable), the pilot of the tow plane may begin a left turn and initiate the descent. In some instances, the glider will release with slack in the tow line. This soft release may not be detectable by the tow pilot. If there is any doubt of the release status in the mind of the tow pilot, the tow pilot should continue the tow and confirm the release via radio or visually.

Descent, Approach and Landing

Descent

During the descent, proper engine management is essential. Good engine conservation practices require a gradual power reduction and conservative descent airspeeds. In fact, studies indicate that airspeed may be more critical than power reduction. Therefore, every attempt should be made to avoid airspeed acceleration and power reduction for 3 minutes after glider release. Full flaps or slipping turns can be used to obtain a suitable rate of descent. Closing cowl flaps, if available, further reduces the rate of engine cooling. Realize oil temperature is not as reliable as cylinder head temperature for managing temperature change. Each airplane requires slightly different techniques; however, the goal is to keep the engine as warm as possible while descending at a reasonable rate.

Collision avoidance is always a high priority, since descending flight attitudes increase the potential of a mid-air collision. Consider developing and using specific descent corridors that are void of glider and power traffic.

Approach and Landing

A 200-foot tow line hangs down behind the tow plane at a 30 to 40 degree angle. The altitude of the tow plane must be adjusted to ensure the tow line does not become entangled in obstructions at close proximity to the ground.

Ensure you are thoroughly briefed and familiar with the obstructions around the airport, especially obstructions on the approach end of the runway to be used. Briefings should include a minimum above ground level (AGL) obstruction crossing height and any factors that may influence altitude judgment, such as visual illusions or other airport distractions.

Landing with the tow line attached is not prohibited by regulation; however, the following points should be considered:

Obstructions are cleared by more than the tow line length (altimeter lag considered).
The field is well turfed. It is simply inviting early tow line failure from abrasion to land with the tow line on hard ground or paved runways. Landing with the tow line should never be attempted unless the field has clear approaches and is at least 2,500 feet in length.

Other situations require the tow line to be dropped, normally in the glider launch area, during short approach to the runway. If the tow line is to be dropped, the tow pilot must be constantly aware of the launch area situation. The tow line drop area must be defined and ground personnel must be briefed and aware of the drop area. Ground personnel must stay clear of the drop area, and the presence of an individual in the drop area requires an immediate go-around by the pilot of the tow plane without dropping the tow line.

Flight Literacy Recommends

Takeoff and Climb

Filed Under: Glider Towing

The takeoff is done by advancing the throttle smoothly and quickly in one motion. [Figure 12-11] If the tow plane is allowed to accelerate and then slow down, the glider may overrun the tow line. This may result in the tow line becoming tangled in the landing gear of the glider. The glider may then be unable to release. Accelerate to liftoff speed keeping in mind that during the takeoff phase of flight, ground effect produces some important relationships. The tow plane leaving ground effect will:

Require an increase in the angle of attack (AOA) to maintain the same lift coefficient;
Experience an increase in induced drag and thrust required;
Experience a decrease in stability and a nose-up change in moment; and
Produce a reduction in static source pressure and increase in indicated airspeed.

Figure 12-11. The takeoff is done by smoothly and quickly advancing the throttle in one motion so that the glider does not overrun the tow line.

These general effects should point out the possible danger in attempting takeoff prior to achieving the recommended lift-off speed. Due to the reduced drag in ground effect, the tow plane may seem capable of takeoff well below the recommended speed; however, lifting out of ground effect with a lower than normal lift off speed may result in very marginal initial climb performance.

The glider will normally liftoff first. The pilot of the glider should correct for crosswind until the tow plane becomes airborne.

At this point, the tow pilot must remain extra alert. The tail of the tow plane may be lifted if the glider climbs too high. Should this happen, the application of full-up elevator on the tow plane may not be sufficient to prevent an accident from happening. The tow pilot must be ready to pull the release handle, releasing the glider and regaining control. As a rule of thumb, the use of a 200 foot tow line would require the glider to climb to over 20 feet above the altitude of the tow plane to present a danger of upset.

After liftoff, a constant airspeed climb should be established. The pilot of the glider should establish a position directly behind the tow plane. The pilot of the tow plane should maintain a constant ground track on the initial climb. Upon reaching a safe altitude, a turn may be established to maintain the desired departure path. Bank angle should be limited to a maximum of 15–20°.

Climb at full throttle unless otherwise required by the POH. The fuel/air mixture should be leaned only in accordance with the POH for maximum power. Each specific model of glider has a published maximum aerotow speed, and the tow pilot must be familiar with this speed, which may be very close to the minimum safe speed of the tow plane. [Figure 12-12]

The tow pilot should understand that these are maximum airspeeds. Plan to fly at a speed slower than the maximum while maintaining safe tow plane flying speed. When towing a different model of glider for the first time, obtain a briefing from the glider pilot to ensure compliance with maximum operating speeds. Also note fiberglass gliders, like the ASK- 21, are towed faster than other popular training gliders.

Recommended towing speed is determined by considering stall speed and maximum aerotow speed of the glider, minimum speed for proper engine cooling of the tow plane, and stall speed of the tow plane. Generally speaking, aerotow should be conducted at the slowest speed possible considering these factors and safety. Speed should be at least thirty percent above stall speed of the glider and twenty percent above the stall speed of the tow plane.

Because of the potential for low altitude emergencies, the initial climb must remain upwind and within gliding distance of the airport. If circumstances do not permit an upwind departure, plan the climb to remain in a position that allows the glider to return to the traffic pattern with the existing headwind component.

When towing, expect the glider to practice maneuvers such as “Boxing the Wake,” which is explained and illustrated in Chapter 7 of this handbook. A thoughtful glider pilot communicates the intention to maneuver behind the tow plane. However, the tow pilot should remain alert for unannounced maneuvering. Glider pilot’s normally begin the “Box the Wake” maneuver by descending vertically from high tow position to low tow position. Once a similar maneuver is detected, maintain a constant heading and a wings level attitude. After the “Box the Wake” maneuver is completed and the glider is stabilized in the hig-tow position, turns can be resumed.

During tow, the glider instructor may demonstrate and practice slack rope recovery procedures. This maneuver normally involves a climb to one side or the other followed by a small dive to create the slack in the tow line. The instructor will then have the student take the slack out of the tow line without breaking the rope. Be alert for these maneuvers and do not mistake the climb and dive maneuver as a release. This maneuver is discussed in further detail in Chapter 8 of this handbook.

Flight Literacy Recommends

Ground Signals

Filed Under: Glider Towing

In most cases, the Standard American Soaring Signals are used to communicate between the launch crew and tow plane. In some cases, however, specific local procedures may be in effect. The tow pilot should be thoroughly briefed on any specific local procedures. The tow pilot may be required to observe these signals through the mirror or through an additional signal relay person positioned safely on the side of the runway adjacent to the tow plane. The ground signals are listed below and are also presented as illustrations in Chapters 7 and 8 of this handbook.

Take up slack—the take up slack signal is given by the ground crewmember moving his or her lowered arm from side to side. When you receive this signal, slowly taxi the tow plane forward to take up the slack in the tow line. When all the slack has been taken from the tow line, expect to receive the “hold” signal from the ground crew.
Hold—this signal is given by holding the arms out straight.
Pilot ready, wings level—when the glider pilot is ready for takeoff, a thumbs up signal is given and the wing runner will level the wing to the takeoff position.
Begin takeoff—the glider pilot waggles the rudder with the wings level and the wing runner signals with a circular motion of the arm. When ready for takeoff, the tow pilot should broadcast on the CTAF that a glider launch is about to be initiated. For example, “Tallahasee traffic, N12345 taking off Runway 33, glider in tow, Tallahasee.” Remember, 14 CFR part 91, section 91.309, requires that before conducting towing operations within Class B, C, D, or E airspace designated for an airport, or before making each towing flight within such controlled airspace if required by ATC, the pilot in charge (PIC) must notify the control tower. If a control tower does not exist or is not in operation, the PIC must notify the FAA flight service station (FSS) serving that controlled airspace before conducting any towing operations.
Stop engine/release tow line—this signal is given by moving a hand back and forth across the throat.
Tow plane ready—prior to takeoff, carefully look at the glider to ensure the glider dive brakes are closed and no one is standing in front of the wings or so close to the launch path to create a hazard. It is important to note, however, that some high-performance gliders may make their initial takeoff roll with spoilers open. Know your gliders and if in doubt, do not be ashamed to question the glider pilot. Better to be a bit embarrassed than to end up in the trees at the end of the runway. Additionally, the tow pilot should ensure that the traffic pattern is clear of aircraft. Once assured that the glider is ready and the briefed departure path is clear, the ready for takeoff signal may be given with a waggle of the tow plane rudder.
Stop operation or emergency—this signal is given by a waving motion of the arms above the head.