Sensory Systems for Orientation

Orientation is the awareness of the position of the aircraft and of oneself in relation to a specific reference point. Disorientation is the lack of orientation, and spatial disorientation specifically refers to the lack of orientation with regard to position in space and to other objects.

Orientation is maintained through the body's sensory organs in three areas: visual, vestibular, and postural. The eyes maintain visual orientation; the motion sensing system in the inner ear maintains vestibular orientation; and the nerves in the skin, joints, and muscles of the body maintain postural orientation. When human beings are in their natural environment, these three systems work well. However, when the human body is subjected to the forces of flight, these senses can provide misleading information. It is this misleading information that causes pilots to become disoriented.

Orientation: Awareness of the position of the aircraft and of oneself in relation to a specific reference point.

Spatial disorientation: The state of confusion due to misleading information being sent to the brain from various sensory organs, resulting in a lack of awareness of the aircraft position in relation to a specific reference point.

ELEMENTS OF HUMAN FACTORS ON FLYING INSTRUMENTS

Human factors is a broad field that studies the interaction between people and machines for the purpose of improving performance and reducing errors. As aircraft became more reliable and less prone to mechanical failure, the percentage of accidents related to human factors increased. Some aspect of human factors now accounts for over 80 percent of all accidents. Pilots who have a good understanding of human factors are better equipped to plan and execute a safe and uneventful flight.

Flying in instrument meteorological conditions (IMC) can result in sensations that are misleading to the body's sensory system. A safe pilot needs to understand these sensations and effectively counteract them. Instrument flying requires a pilot to make decisions using all available resources.

The elements of human factors covered in this chapter include sensory systems used for orientation, illusions in flight, physiological and psychological factors, medical factors, aeronautical decision making, and crew/cockpit resource management.

Human factors: A multidisciplinary field encompassing the behavioral and social sciences, engineering, and physiology, to consider the variables that influence individual and crew performance for the purpose of reducing errors.

AERONAUTICAL GLOSSARY : SPATIAL DISORIENTATION - STABILITY

SPATIAL DISORIENTATION— Specifically refers to the lack of orientation with regard to the position, attitude, or movement of the airplane in space.

SPECIAL FLIGHT PERMIT—A flight permit issued to an aircraft that does not meet airworthiness requirements but is capable of safe flight. A special flight permit can be issued to move an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, or customer demonstration. Also referred to as a ferry permit.

SPECIAL USE AIRSPACE— Airspace that exists where activities must be confined because of their nature.

SPECIFIC FUEL CONSUMPTION—The amount of fuel in pounds per hour consumed or required by an engine per brake horsepower or per pound of thrust.

SPEED—The distance traveled in a given time.

SPIN—An aggravated stall that results in an airplane descending in a helical, or corkscrew path.

SPIRAL INSTABILITY—A condition that exists when the static directional stability of the airplane is very strong as compared to the effect of its dihedral in maintaining lateral equilibrium.

SPIRALING SLIPSTREAM—The slipstream of a propeller-driven airplane rotates around the airplane. This slipstream strikes the left side of the vertical fin, causing the aircraft to yaw slightly. Rudder offset is sometimes used by aircraft designers to counteract this tendency.

SPOILERS—High-drag devices that can be raised into the air flowing over an airfoil, reducing lift and increasing drag. Spoilers are used for roll control on some aircraft. Deploying spoilers on both wings at the same time allows the aircraft to descend without gaining speed. Spoilers are also used to shorten the ground roll after landing.

STABILATOR—A single-piece horizontal tail surface on an airplane that pivots around a central hinge point. A stabilator serves the purposes of both the horizontal stabilizer and the elevators.

STABILITY—The inherent quality of an airplane to correct for conditions that may disturb its equilibrium, and to return or to continue on the original flightpath. It is primarily an airplane design characteristic.

AERONAUTICAL GLOSSARY : RUNWAY END IDENTIFIER LIGHTS (REIL) - SKILLS AND PROCEDURES

RUNWAY END IDENTIFIER LIGHTS (REIL)—One component of the runway lighting system. These lights are installed at many airfields to provide rapid and positive identification of the approach end of a particular runway.

SEA BREEZE—A coastal breeze blowing from sea to land caused by the temperature difference when the land surface is warmer than the sea surface. The sea breeze usually occurs during the day and alternates with the land breeze that blows in the opposite direction at night.

SEA-LEVEL ENGINE—A reciprocating aircraft engine having a rated takeoff power that is producible only at sea level.

SECTIONAL AERONAUTICAL CHARTS (1:500,000)—Designed for visual navigation of slow or medium speed aircraft. Topographic information on these charts features the portrayal of relief, and a judicious selection of visual check points for VFR flight. Aeronautical information includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.

SEMI-MONOCOQUE—A fuselage design that includes a substructure of bulkheads and/or formers, along with stringers, to support flight loads and stresses imposed on the fuselage.

SERVICE CEILING—The maximum density altitude where the best rate-of-climb airspeed will produce a 100 feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.

SERVO—A motor or other form of actuator which receives a small signal from the control device and exerts a large force to accomplish the desired work.

SERVO TAB—An auxiliary control mounted on a primary control surface, which automatically moves in the direction opposite the primary control to provide an aerodynamic assist in the movement of the control.

SIGMET—An in-flight weather advisory that is considered significant to all aircraft. SIGMET criteria include severe icing, severe and extreme turbulence, duststorms, sandstorms, volcanic eruptions, and volcanic ash that lower visibility to less than 3 miles.

SIGNIFICANT WEATHER PROGNOSTIC CHART—Presents four panels showing forecast significant weather and forecast surface weather.

SITUATIONAL AWARENESS— The accurate perception and understanding of all the factors and conditions within the four fundamental risk elements that affect safety before, during, and after the flight.

SKILLS AND PROCEDURES— The procedural, psychomotor, and perceptual skills used to control a specific aircraft or its systems. They are the airmanship abilities that are gained through conventional training, are perfected, and become almost automatic through experience.

AERONAUTICAL GLOSSARY : RELATIVE BEARING - RUNWAY EDGE LIGHTS

RELATIVE BEARING—An angular relationship between two objects measured in degrees clockwise from the twelve o'clock position of the first object.

RELATIVE HUMIDITY — The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature; usually expressed in percent.

RELATIVE WIND—The direction of the airflow with respect to the wing. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flightpath of the airplane.

RESTRICTED AREAS—Areas that denote the existence of unusual, often invisible hazards to aircraft such as artillery firing, aerial gunnery, or guided missiles. An aircraft may not enter a restricted area unless permission has been obtained from the controlling agency.

RIGGING—The final adjustment and alignment of an aircraft and its flight control system that provides the proper aerodynamic characteristics.

RIGIDITY IN SPACE—The principle that a wheel with a heavily weighted rim spun rapidly will remain in a fixed position in the plane in which it is spinning.

RISK ELEMENTS—There are four fundamental risk elements: the pilot, the aircraft, the environment, and the type of operation that comprise any given aviation situation.

RISK MANAGEMENT—The part of the decision making process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated with each flight.

RNAV—See AREA NAVIGATION.

RUDDER—The movable primary control surface mounted on the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis.

RUDDERVATOR—A pair of control surfaces on the tail of an aircraft arranged in the form of a V. These surfaces, when moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve as a rudder.

RUNWAY CENTERLINE LIGHTS—Runway lighting which consists of flush centerline lights spaced at 50-foot intervals beginning 75 feet from the landing threshold.

RUNWAY EDGE LIGHTS—A component of the runway lighting system that is used to outline the edges of runways at night or during low visibility conditions. These lights are classified according to the intensity they are capable of producing.

AERONAUTICAL GLOSSARY : PRESSURE DEMAND OXYGEN SYSTEM - REGION OF REVERSE COMMAND

PRESSURE DEMAND OXYGEN SYSTEM—Ademand oxygen system that supplies 100 percent oxygen at sufficient pressure above the altitude where normal breathing is adequate. Also referred to as a pressure breathing system.

PREVENTIVE MAINTENANCE—Simple or minor preservative operations and the replacement of small standard parts not involving complex assembly operation as listed in Appendix A of 14 CFR part 43. Certificated pilots may perform preventive maintenance on any aircraft that is owned or operated by them provided that the aircraft is not used in air carrier service.

PROHIBITED AREAS—Areas that are established for security or other reasons associated with the national welfare.

PROPELLER—A device for propelling an aircraft that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes the control components normally supplied by its manufacturer.

RADAR SERVICES—Radar is a method whereby radio waves are transmitted into the air and are then received when they have been reflected by an object in the path of the beam. Range is determined by measuring the time it takes (at the speed of light) for the radio wave to go out to the object and then return to the receiving antenna. The direction of a detected object from a radar site is determined by the position of the rotating antenna when the reflected portion of the radio wave is received.

RADAR SUMMARY CHART—A weather product derived from the national radar network that graphically displays a summary of radar weather reports.

RADAR WEATHER REPORT (SD)—A report issued by radar stations at 35 minutes after the hour, and special reports as needed. Provides information on the type, intensity, and location of the echo tops of the precipitation.

RADIOSONDE—Aweather instrument that observes and reports meteorological conditions from the upper atmosphere. This instrument is typically carried into the atmosphere by some form of weather balloon.

RAM RECOVERY—The increase in thrust as a result of ram air pressures and density on the front of the engine caused by air velocity.

RAPID DECOMPRESSION—The almost instantaneous loss of cabin pressure in aircraft with a pressurized cockpit or cabin.

REGION OF REVERSE COMMAND —Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.

AERONAUTICAL GLOSSARY : PILOTAGE - PRESSURE ALTITUDE

PILOTAGE—Navigation by visual reference to landmarks.

PILOT'S OPERATING HANDBOOK (POH)—A document developed by the airplane manufacturer and contains the FAA-approved Airplane Flight Manual (AFM) information.

PILOT WEATHER REPORT (PIREP)A report, generated by pilots, concerning meteorological phenomena encountered in flight.

PLANFORM—The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.

PNEUMATIC—Operation by the use of compressed air.

POOR JUDGMENT CHAIN—A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of a poor judgment chain are: (1) One bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. ADM is intended to break the poor judgment chain before it can cause an accident or incident.

POSITIVE STATIC STABILITY— The initial tendency to return to a state of equilibrium when disturbed from that state.

POWER—Implies work rate or units of work per unit of time, and as such, it is a function of the speed at which the force is developed. The term, power required, is generally associated with reciprocating engines.

POWERPLANT—A complete engine and propeller combination with accessories.

PRECESSION—The tilting or turning of a gyro in response to deflective forces causing slow drifting and erroneous indications in gyroscopic instruments.

PRECIPITATION—Any or all forms of water particles (rain, sleet, hail, or snow), that fall from the atmosphere and reach the surface.

PREIGNITION—Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel-air mixture.

PRESSURE ALTITUDE—The altitude indicated when the altimeter setting window (barometric scale) is adjusted to 29.92. This is the altitude above the standard datum plane, which is a theoretical plane where air pressure (corrected to 15ºC) equals 29.92 in. Hg. Pressure altitude is used to compute density altitude, true altitude, true airspeed, and other performance data.

AERONAUTICAL GLOSSARY : NOTICES TO AIRMEN (NOTAM) - PHUGOID OSCILLATIONS

NOTICES TO AIRMEN (NOTAM)—A notice containing time-critical information that is either of a temporary nature or is not known far enough in advance to permit publication on aeronautical charts or other operation publications. This can include the establishment, condition, or change in any facility, service, procedure, or hazard in the National Airspace System.

OBSTRUCTION LIGHTS—Lights that can be found both on and off an airport to identify obstructions.

OCCLUDED FRONT—A frontal occlusion occurs when a fast-moving cold front catches up with a slowmoving warm front. The difference in temperature within each frontal system is a major factor in determining whether a cold or warm front occlusion occurs.

OUTSIDE AIR TEMPERATURE (OAT)—The measured or indicated air temperature (IAT) corrected for compression and friction heating. Also referred to as true air temperature.

OVERBOOST—A condition in which a reciprocating engine has exceeded the maximum manifold pressure allowed by the manufacturer. Can cause damage to engine components.

PARALLELS—Lines of latitude.

PARASITE DRAG—That part of total drag created by the form or shape of airplane parts. Parasite drag increases with an increase in airspeed.

PAYLOAD (GAMA)—The weight of occupants, cargo, and baggage.

PERSONALITY—The embodiment of personal traits and characteristics of an individual that are set at a very early age and extremely resistant to change.

P-FACTOR—A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft's longitudinal axis is in a climbing attitude in relation to the relative wind. The P factor would be to the right if the aircraft had a counterclockwise rotating propeller.

PHUGOID OSCILLATIONS — Long-period oscillations of an aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle of attack remains constant, and the pilot often corrects for phugoid oscillations without even being aware of them.

AERONAUTICAL GLOSSARY : MOMENT - NONDIRECTIONAL RADIO BEACON (NDB)

MOMENT—The product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (lb-in). Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.

MOMENT ARM—The distance from a datum to the applied force.

MOMENT INDEX (OR INDEX)— A moment divided by a constant such as 100, 1,000, or 10,000. The purpose of using a moment index is to simplify weight and balance computations of airplanes where heavy items and long arms result in large, unmanageable numbers.

MONOCOQUE—A shell-like fuselage design in which the stressed outer skin is used to support the majority of imposed stresses. Monocoque fuselage design may include bulkheads but not stringers.

MONOPLANES—Airplanes with a single set of wings.

MOVABLE SLAT—A movable auxiliary airfoil on the leading edge of a wing. It is closed in normal flight but extends at high angles of attack. This allows air to continue flowing over the top of the wing and delays airflow separation.

N1—Rotational speed of the low pressure compressor in a turbine engine.

N2—Rotational speed of the high pressure compressor in a turbine engine.

NACELLE—A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven airplanes, the nacelle is normally mounted on the leading edge of the wing.

NATIONAL SECURITY AREAS— Airspace that consists of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities.

NDB—See NONDIRECTIONAL RADIO BEACON.

NEGATIVE STATIC STABILITY—The initial tendency of an aircraft to continue away from the original state of equilibrium after being disturbed.

NEUTRAL STATIC STABILITY— The initial tendency of an aircraft to remain in a new condition after its equilibrium has been disturbed.

NONDIRECTIONAL RADIO BEACON (NDB)—An L/MF or UHF radio beacon transmitting non directional signals whereby the pilot of an aircraft equipped with direction finding equipment can determine the bearing to or from the radio beacon and "home" on or track to or from the station. When the radio beacon is installed in conjunction with the Instrument Landing System marker, it is normally called a Compass Locator.

AERONAUTICAL GLOSSARY : MAXIMUM LANDING WEIGHT - MINIMUM EQUIPMENT LIST (MEL)

MAXIMUM LANDING WEIGHT—The greatest weight that an airplane normally is allowed to have at landing.

MAXIMUM RAMP WEIGHT— The total weight of a loaded aircraft, including all fuel. It is greater than the takeoff weight due to the fuel that will be burned during the taxi and run up operations. Ramp weight may also be referred to as taxi weight.

MAXIMUM TAKEOFF WEIGHT—The maximum allowable weight for takeoff.

MAXIMUM WEIGHT—The maximum authorized weight of the aircraft and all of its equipment as specified in the Type Certificate Data Sheets (TCDS) for the aircraft.

MAXIMUM ZERO FUEL WEIGHT (GAMA)—The maximum weight, exclusive of usable fuel.

MEAN AERODYNAMIC CHORD (MAC)—The average distance from the leading edge to the trailing edge of the wing.

MERIDIANS—Lines of longitude.

MESOSPHERE—A layer of the atmosphere directly above the stratosphere.

METAR—See AVIATION ROUTINE WEATHER REPORT.

MICROBURST—A strong downdraft which normally occurs over horizontal distances of 1 NM or less and vertical distances of less than 1,000 feet. In spite of its small horizontal scale, an intense microburst could induce windspeeds greater than 100 knots and downdrafts as strong as 6,000 feet per minute.

MILITARY OPERATION AREAS (MOA)—Airspace that consists of defined vertical and lateral limits established for the purpose of separating certain military training activity from IFR traffic. These are depicted on aeronautical charts.

MILITARY TRAINING ROUTES (MTR)—Routes developed to allow the military to conduct low altitude, high-speed training. These routes are identified on sectional charts.

MINIMUM DRAG—The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag is minimized.

MINIMUM EQUIPMENT LIST (MEL)—A list developed for larger aircraft that outlines equipment that can be inoperative for various types of flight including IFR and icing conditions. This list is based on the master minimum equipment list (MMEL) developed by the FAA and must be approved by the FAA for use. It is specific to an individual aircraft make and model.

AERONAUTICAL GLOSSARY : LONGITUDE - MASS

LONGITUDE—Measurement east or west of the Prime Meridian in degrees, minutes, and seconds. The Prime Meridian is 0° longitude and runs through Greenwich, England. Lines of longitude are also referred to as meridians.

LONGITUDINAL AXIS—An imaginary line through an aircraft from nose to tail, passing through its center of gravity. The longitudinal axis is also called the roll axis of the aircraft. Movement of the ailerons rotates an airplane about its longitudinal axis.

LONGITUDINAL STABILITY (PITCHING)—Stability about the lateral axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.

LORAN-C—A radio navigation system that utilizes master and slave stations transmitting timed pulses. The time difference in reception of pulses from several stations establishes a hyperbolic line of position, which can be identified on a LORAN chart. A fix in position is obtained by utilizing signals from two or more stations.

MAGNETIC BEARING—The magnetic course to go direct to an NDB station.

MAGNETIC COMPASS—A device for determining direction measured from magnetic north.

MAGNETIC DIP—Avertical attraction between a compass needle and the magnetic poles. The closer the aircraft is to the pole, the more severe the effect. In the Northern Hemisphere, a weight is placed on the south-facing end of the compass needle; in the Southern Hemisphere, a weight is placed on the north-facing end of the compass needle to somewhat compensate for this effect.

MAGNETO—A self-contained, engine-driven unit that supplies electrical current to the spark plugs; completely independent of the airplane's electrical system. Normally there are two magnetos per engine.

MAGNUS EFFECT—Lifting force produced when a rotating cylinder produces a pressure differential. This is the same effect that makes a baseball curve or a golf ball slice.

MANEUVERABILITY—Ability of an aircraft to change directions along a flightpath and withstand the stresses imposed upon it.

MANEUVERING SPEED (VA) — The maximum speed where full, abrupt control movement can be used without overstressing the airframe.

MANIFOLD ABSOLUTE PRESSURE (MAP)—The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury.

MASS—The amount of matter in a body.

AERONAUTICAL GLOSSARY : JUDGMENT - LOAD FACTOR

JUDGMENT—The mental process of recognizing and analyzing all pertinent information in a particular situation, a rational evaluation of alternative actions in response to it, and a timely decision on which action to take.

LAND BREEZE—A coastal breeze flowing from land to sea caused by temperature differences when the sea surface is warmer than the adjacent land. The land breeze usually occurs at night and alternates with the sea breeze that blows in the opposite direction by day.

LATERAL AXIS—An imaginary line passing through the center of gravity of an airplane and extending across the airplane from wingtip to wingtip.

LATERAL STABILITY (ROLLING)—The stability about the longitudinal axis of an aircraft. Rolling stability or the ability of an airplane to return to level flight due to a disturbance that causes one of the wings to drop.

LATITUDE—Measurement north or south of the equator in degrees, minutes, and seconds. Lines of latitude are also referred to as parallels.

LEADING EDGE—The part of an airfoil that meets the airflow first.

LEADING EDGE DEVICES — High lift devices which are found on the leading edge of the airfoil. The most common types are fixed slots, movable slats, and leading edge flaps.

LEADING EDGE FLAP—A portion of the leading edge of an airplane wing that folds downward to increase the camber, lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount of aerodynamic lift that is produced at any given airspeed.

LICENSED EMPTY WEIGHT— The empty weight that consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment as specified in the equipment list. Some manufacturers used this term prior to GAMA standardization.

LIFT—One of the four main forces acting on an aircraft. On a fixed-wing aircraft, an upward force created by the effect of airflow as it passes over and under the wing.

LIMIT LOAD FACTOR—Amount of stress, or load factor, that an aircraft can withstand before structural damage or failure occurs.

LOAD FACTOR—The ratio of the load supported by the airplane's wings to the actual weight of the aircraft and its contents. Also referred to as loading.