with internal heating elements and rechargeable lithium batteries that the pilot can turn on and regulate. These make a great
addition to a glider pilot’s wardrobe.
Low temperatures can cause other unpleasant or hazardous conditions. Pilot or passenger exhaled moisture can condense
and then freeze or deposit directly as frost on the inside of the canopy. The pilot can use a clean piece of cloth that does
not damage the canopy to wipe off condensation or light frost. Allowing fresh air through a vent can clear condensation
and stop frost formation. Unfortunately, this also quickly lowers the inside temperature, and may require adding a layer of
clothing.
The body dehydrates more rapidly in extreme cold and refraining from drinking water can cause dehydration even in cold
conditions. Because cold weather causes the kidneys to excrete liquid at a faster rate, the pilot should make a bathroom
stop before takeoff and consider a relief system for the flight.
Cabin Management & Equipment
Prior to launch, the pilot should brief any passengers on use of safety belts, shoulder harnesses, and emergency procedures.
The pilot should check the security of any trim ballast, organize the items carried onboard, and properly stow and secure
all other items. Placement of charts, tablets, and cross-country aids should allow the pilot to reach them easily.
Parachute
Pilots may use a parachute for emergencies. A certificated and appropriately rated parachute rigger must repack a nylon
parachute within the preceding 180 days. The packing date information is usually found on a card contained in a small
pocket on the body of the parachute. Refer to 14 CFR, part 91, section 91.307 for more information.
Supplemental Oxygen
High-altitude soaring flights require the use of supplemental oxygen. In some parts of the country, soaring routinely occurs
to a 16,000- to 18,000-foot cloud base in thermals. Flight using mountain waves may lead to flight at altitudes more than
30,000 feet in the United States.
Breathing supplies oxygen to the blood and removes carbon dioxide. In each breath at 18,000 feet, the pilot breathes in only
half as much oxygen as at sea level. The pilot’s automatic reaction without an adequate supply of oxygen would involve
breathing twice as fast. This hyperventilation, or over-breathing, would result in eliminating too much carbon dioxide from
the blood.
14 CFR, part 91, section 91.211, dictates time and altitude requirements for use of supplemental oxygen. Prior to use
of supplemental oxygen, the system should be checked for oxygen availability and flow. The pilot can use the PRICE
checklist:
• P = Pressure
• R = Regulator
• I = Indicator
• C = Connections
• E = Emergency bail-out bottle
Aviation Oxygen Systems
A portable aviation oxygen system delivers oxygen using lightweight and compact components. It delivers a calibrated
amount of oxygen based on extensive research in human flight physiology. Prior to purchasing any type of oxygen
system, pilots should consider the type of flying they do. Two different common types of systems used today include
the Continuous-Flow System and the Electronic Pulse Demand Oxygen System (EDS). Pilots should only use aviator’s
oxygen supplied in a green bottle with these systems and never use medical oxygen. Medical oxygen may contain water
and could render a pilot’s oxygen system unworkable.
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 flows continuously
when the system is turned on provided the bottle contains sufficient oxygen. In some installations, the pilot can 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]
Figure 13-9. Continuous-flow oxygen system.
Figure 13-10. Oxygen mask.
Figure 13-11. Nasal cannula.
Electronic Pulse Demand Oxygen System (EDS)
The EDS delivers altitude-compensated pulses of oxygen only when the pilot inhales. It typically uses 1⁄6 the amount
of oxygen at 1⁄4 the weight and volume of conventional constant-flow systems. [ Figure 13-12] The EDS has a micro-
electronic pressure altitude barometer that automatically determines the volume for each oxygen pulse up to pressure
altitudes of 32,000 feet. The EDS automatically goes to a 100 percent pulse-demand mode at pressure altitudes above
32,000 feet.
Figure 13-12. Electronic Pulse Demand Oxygen System (EDS).
The pilot can set an EDS to different modes and delays. For example, it can respond with oxygen at altitudes where needed
and conserve oxygen at lower altitudes. It can also be set to night or now mode where it responds from sea-level and
up. The EDS limits its response to a maximum respiration rate of about 20 breaths per minute, virtually eliminating any
hyperventilation. The pilot turns it on and does not need to read scales or adjust any knobs when climbing or descending.
These devices need no local altimeter setting since they respond directly to pressure altitude, just as the body does.
Risk Management
Risk management for pilots includes identification of hazards that pose a flight risk, assessment of the level of risk
associated with each hazard, and decision making to manage and mitigate any unacceptable risks.
Hazards include any condition that can foreseeably cause or contribute to an aircraft accident. Typical hazards include
pilot condition or lack of proficiency, aircraft or equipment malfunctions or shortcomings, and environmental conditions
that include weather, mountains, obstacles, other aircraft, wires, and high-altitude flight. Any external pressure to take a
particular flight can create an additional hazard. These items form part of the PA VE checklist (Pilot, Aircraft, enVironment,
External pressure) that pilots can use to consider and manage common flight risks.
The composite of predicted severity and likelihood of the potential effect of a hazard constitutes the risk. The level of
risk associated with a hazard depends on the likelihood of an accident and the severity of damage or injury that could
occur. Risk mitigation involves an analysis and implementation of changes the pilot can make to lower the level of risk.
For example, a glider pilot recognizes the risk associated with a tow line break. The pilot lowers the level of this risk by
training for this possibility. Before each tow, the pilot should also consider a plan of action in the event of a rope break. If
that consideration does not adequately mitigate that risk for the given set of conditions on a particular day, the pilot might
decide to wait for the winds to change, ask for a different direction of tow, or postpone or cancel the operation.
Safety Management System (SMS)
This Handbook focuses on the individual and not on safety management systems (SMS). SMS addresses risk management
from an organizational perspective as an ongoing activity. Interested persons may obtain information about SMS from the
Risk Management Handbook (FAA-H-8083-2).
Aeronautical Decision-Making (ADM)
A pilot makes numerous aeronautical decisions involving risk management before a flight begins. One structured
means involves using a Flight Risk Assessment Tool or FRAT. Pilots can check the FAA Risk Management Handbook
(FAA-H-8083-2) for a sample FRAT and can use one to enhance the safety of flight.
FAA regulations set up specific minimum safety requirements for some conditions, but that does not mean every pilot has
the capability to fly in those conditions. As previously mentioned, pilots can establish their own more stringent rules for
the personal, equipment, and environmental conditions that might lead them to decide not to fly on a given day. The FAA
Risk Management Handbook (FAA-H-8083-2) has a chapter explaining the rationale for personal minimums in more detail
and how to establish and maintain these minimums.
Aeronautical decision-making (ADM) in flight usually involves a systematic mental process pilots use to determine a
course of action in response to a given set of circumstances. Pilots should perceive any hazards that threaten the safety
of flight, determine a course of action that will lead to a successful outcome, and then perform the steps expected to lead
to that successful outcome. The process of hazard perception, situation processing, and performance should repeat as the
flight progresses. At the conclusion of a flight the pilot can self-assess on the quality of decision making.
Despite advancement in training methods, airplane equipment and systems, and services for pilots, incidents and accidents
still occur. Despite all the changes in technology to improve flight safety, the human factor plays a role in a high percentage
of all aviation accidents.
Human factor-related accidents usually do not involve a single decision but result from a chain of decisions and factors
that might lead to an accident. An error chain describes the sequence of several events in a human factors-related accident.
Breaking one link in the chain would normally change the outcome of the sequence of events.
This list presents different hazards and pilot responses. Did these pilots carefully consider the consequences of their
decisions?
• Circumstance: My oxygen system has a slow leak. Decision: Soaring conditions are perfect, and I will not need
oxygen for today.
• Circumstance: High winds are forecast later today. Decision: I can fly and make it back before the wind changes.
• Circumstance: My aircraft or radio batteries are low. Decision: I am only planning a short flight, so I’ll go.
Circumstances as mundane as a slow oxygen leak, a high wind forecast, or low batteries become part of a decision chain
that can lead to an incident or accident. In the previous circumstances, the pilot might interrupt an accident chain by having
the slow oxygen leak repaired, respecting the high wind forecast and postponing the flight, or recharging the low batteries
before the flight.
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. This AC also provides instructors with methods for teaching ADM techniques and skills
in conjunction with conventional flight instruction. Individuals learning to fly gliders should seek out instructors who
integrate ADM training. The FAA Risk Management Handbook (FAA-H-8083-2) provides an overview and examples of
what pilots do to make their flights safe and enjoyable.
Analysis of Previous Accidents
The National Transportation Safety Board (NTSB) compiles an accident report any time a reportable glider accident
occurs. Interested persons can find this public information at www.ntsb.gov.
An individual using the NTSB’s accident database, can use their supplied query tool to perform a simple search using
the term “glider” (and other optional elements) to retrieve accident reports involving gliders. The detail in these reports
provides a narrative of circumstances and events that led to each accident. Since pilot decisions before and during flight
may have prevented these accidents, a review can illustrate the concept of an accident chain. That understanding should
prompt pilots to make safety and risk mitigation a high priority. Figure 13-13 contains a summary of several glider accident
final reports from the past several years.
Event Date Glider Type Injury Probable Cause
2/9/2020 Aviastroitel AC 4C Fatal The pilot's exceedance of the glider's critical angle of attack while maneuvering for landing, which
resulted in an aerodynamic stall and subsequent loss of control.
3/1/2020 Let L 23 SUPER BLANIK Serious The pilot's failure to maintain glider control and his exceedance of the glider's critical angle of attack
while maneuvering in gusting wind conditions, which resulted in an aerodynamic stall.
4/7/2020 Schempp Hirth Standard Cirrus Fatal
The pilot's exceedance of the glider's critical angle of attack following his premature termination of the
tow for reasons that could not be determined, which resulted in an aerodynamic stall/spin during a turn
back to the departure airport.
5/11/2020 Schempp Hirth VENTUS 2CT Minor A loss of thermal lift during a motor glider flight, which resulted in an off-airport landing. Contributing to
the accident was the pilot's delayed attempted engine start.
6/4/2020 Gilasflugel Mosquito None The pilot's decision to divert to the private airport and his subsequent failure to maintain directional
control while landing on a turf runway that contained tall grass.
6/13/2020 Pipistrel PIPISTREL SINUS 912 None The pilot's failure to maintain airspeed while landing with a quartering tailwind, which resulted in a loss
of control and a hard landing.
7/11/2020 Schleicher ASW27 Fatal The pilot's loss of glider control while maneuvering near a mountain ridge in downdrafts and dry
microbursts at an altitude that precluded recovery.
8/16/2020 Evektor Aerotechnik L13 Serious The pilot's failure to stow the speed brake prior to attempting takeoff.
9/19/2020 ΡIK PIK-200 Minor
The pilot's failure to maintain directional control during takeoff that resulted in a collision with another
glider that was parked close to the departure runway, and the pilot's improper decision to attempt a
takeoff without ensuring he had safe clearance from the parked glider.
9/29/2020 Schleicher ASK21 None The pilot's improper control input during a bounced landing that resulted in the glider impacting terrain.
11/7/2020 Schleicher ASW20C (A1); Schleicher ASW27 (A2) Serious The failure of both pilots of each glider to see an avoid one another while maneuvering, which resulted
in a mid-air collision.
12/27/2020 Glasflugel CLUB LIBELLE 205 Serious The pilot's failure to maintain adequate clearance from trees during an off-airport landing.
4/22/2021 Schempp Hirth Ventus C Serious Impact with trees during a forced landing in atmospheric lift conditions that were insufficient to maintain
flight. Contributing was the pilot's delayed decision to return to the airport.
5/16/2021 I.C.A. BRASOV (ROMANIA) IS- 2882 Serious
The flight instructor's failure to maintain aircraft control resulting in the exceedance of the glider's critical
angle of attack following the breakage of the weak/safety link during a winch launch, which resulted in
an aerodynamic stall and spin, and subsequent impact with trees and terrain.
5/20/2021 Pilatus 84-PC11 Minor The pilot's misjudged approach angle which resulted in impact with trees and terrain.
6/5/2021 Schweizer SGS 2-33A None The pilot's failure to maintain directional control while landing in gusting wind conditions.
6/6/2021 Schweizer SGS 1-35 Fatal
The pilot's low-altitude release from tow for reasons that could not be determined, and his subsequent
exceedance of the glider's critical angle of attack while returning to the runway, which resulted in an
aerodynamic stall and impact with terrain.
6/13/2021 Schweizer SGS 2-33A Serious The student pilot's failure to maintain an appropriate glide path to the runway.
6/20/2021 Schweizer SGS 1-35 Minor The glider pilot's loss of visual references during the landing approach resulting in an offairport landing
on rough sloping terrain.
7/15/2021 ALEXANDER SCHLEICHER GMBH & CO ASW 27-18 None The pilot's failure to maintain the glider's stability in the roll axis during the takeoff roll, which resulted in
a dragged wingtip and ground loop.
7/25/2021 BURKHART GROB G 103 TWIN Minor The glider's encounter with atmospheric conditions where the lift was not sufficient to maintain flight
which resulted in an off-airport landing and a collision with a fence.
8/15/2021 Schweizer SGS 2-33A None The check pilot's failure to account for the extended departure distance from the airport during a
simulated tow rope break and recovery.
9/7/2021 Aeromot AMT-100 None The pilot's failure to extend the landing gear.
10/21/2021 Pipistrel Apis-Bee Serious The pilot's failure to maintain control of the glider during the landing approach, which resulted in an
aerodynamic stall and subsequent impact with the runway.
11/17/2021 PHOENIX AIR U-15 PHOENIX None The pilot's failure to maintain distance with an airport sign while taxiing.
4/8/2022 ALEXANDER SCHLEICHER GMBH & CO ASK 21 None The gliders encounter with atmospheric conditions where the lift was not sufficient to maintain flight and
subsequent impact with mountainous terrain.
6/19/2022 ROLLADEN-SCHNEIDER 15-6 None The glider's encounter with atmospheric conditions where the lift was not sufficient to maintain flight
and subsequent water ditching.
6/22/2022 LET L-23 SUPER BLANIK Serious The pilot's encounter with sinking air conditions that resulted in a loss of lift and a subsequent loss of
control.
6/22/2022 DG FLUGZEUGBAU GMBH DG 10005 None
The glider's encounter with atmospheric conditions where the lift was not sufficient to maintain flight.
Contributing to the accident was the pilot's decision to overfly a suitable landing site which resulted in
an off-field landing in a lake.
7/10/2022 Schleicher ASW-198 None The pilot's misidentification of the runway during the visual approach which resulted in an off runway
landing and impact with a trailer.
Figure 13-13. Glider accident data from the NTSB database.
Chapter Summary
This chapter focuses on the subset of human factors that pilots can control to prevent accidents. Hazardous attitudes play
a role in accidents, and pilot should recognize and avoid them and the types of errors they lead to. The chapter discusses
human physiology related to glider flight. Pilots should know how to take care of their physical needs before and during
flight. The chapter also discusses systems pilots might use during glider flight including oxygen systems. The chapter
discusses risk management and reducing the level of risk to avoid accidents. The NTSB database contains accident reports
that illustrate the concept of an accident chain. While glider flight has inherent associated risk, the principles discussed in
this chapter and throughout this handbook can reduce a glider pilot’s level of exposure to that risk.
Advection. The transport of an atmospheric variable due to mass motion by the wind. Usually the term as used in meteorology
refers only to horizontal transport.
Ailerons. The hinged portion of the trailing edge of the outer wing used to bank or roll around the longitudinal axis.
Air density. The mass of air per unit volume.
Airfoil. The surfaces on a glider that produce lift.
Air mass. A widespread mass of air having similar characteristics (e.g., temperature), that usually helps to identify the
source region of the air. Fronts are distinct boundaries between air masses.
Amplitude. In wave motion, one half the distance between the wave crest and the wave trough.
Angle of attack. The angle formed between the relative wind and the chord line of the wing.
Angle of incidence. The angle between the chord line of the wing and the longitudinal axis of the glider. The angle of
incidence is built into the glider by the manufacturer and cannot be adjusted by the pilot’s movements of the controls.
Aspect ration. The ratio between the wing span and the mean chord of the wing.
Asymmetrical airfoil. One in which the upper camber differs from the lower camber.
Atmospheric sounding. A measure of atmospheric variables aloft, usually pressure, temperature, humidity, and wind.
Atmospheric stability. Describes a state in which an air parcel resists vertical displacement or, once displaced (for instance
by flow over a hill), tends to return to its original level.
Bailout bottle. Small oxygen cylinder connected to the oxygen mask supplying several minutes of oxygen. It can be used
in case of primary oxygen system failure or if an emergency bailout at high altitude became necessary.
Ballast. Term used to describe any system that adds weight to the glider. Performance ballast employed in some gliders
increases wing loading using releasable water in the wings (via integral tanks or water bags). This allows faster average
cross-country speeds. Trim ballast is used to adjust the flying CG, often necessary for light-weight pilots. Some gliders also
have a small water ballast tank in the tail for optimizing flying CG.
Barograph. Instrument for recording pressure as a function of time. Used by glider pilots to verify flight performance for
badge or record flights.
Best glide speed (best L/D speed). The airspeed that results in the least amount of altitude loss over a given distance. This
speed is determined from the performance polar. The manufacturer publishes the best glide (L/D) airspeed for specified
weights and the resulting glide ratio. For example, a glide ratio of 36:1 means that the glider will lose 1 foot of altitude for
every 36 feet of forward movement in still air at this airspeed.
Camber. The curvature of a wing when looking at a cross section. A wing has upper camber on its top surface and lower