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Transcript

IR training slide

Tréner kft.

Why to learn IR?

  • Gives professionality for pilots
  • Necessary for an airline (AWO)
  • increases safety

Professionality

https://www.youtube.com/watch?v=0rDdnJp0NEQ

Professionality

All Weather Operations

  • Airline must operate on schedule
  • Avoiding delays
  • maitaining flight safety on high level
  • increases available airborne time
  • closing up for high demand of passangers

AWO

AWO

History of instrument flying

"It is possible to fly without motors, but not witho...

"It is possible to fly without motors, but not without knowledge and skill."

Wilbur Wright

Wright Brothers

First flight with powered heavier-than-air aircraft: 1903.12.17. Wright Brothers

https://www.youtube.com/watch?v=RriKI7u72Xs

Wright Brothers

Lt. James Doolittle

1929.09.24.

First flight based on instruments

Lt. James Doolittle

1929.09.24.

Lt. James Doolittle and NY-2

Lt. James Doolittle and NY-2

Albert Francis Hegenberger

1932.05.09.

Albert Francis Hegenberger

Albert Francis Hegenberger

  • McCook Field, Ohio
  • Very first solo instrument approach and landing, using a system which he had developed
  • Hegenberger system: used a series of non-directional beacons (NDB)
  • Was awarded an oak leaf cluster
  • greatest achievement in aeronautics in America.

First landing using ILS system:

1938.01.26.

Pittsbugh airport

Pennsylvania Central Airlines

https://www.youtube.com/watch?v=mgBf4QJK73Y

First landing using ILS system:

1938.01.26.

First VHF Omniderectional Range transmitter

1946

First VHF Omniderectional Range transmitt...

First fully automatic landing using ILS system

1964 March

Bradford Airport UK

First fully automatic landing using ILS syst...

https://www.youtube.com/watch?v=tqRXtFObrxI

Global Positioning System

1978

Stand-alone GPS approaches

1994

https://www.youtube.com/watch?v=mTdwYvDHY00

Stand-alone GPS approaches

1994

GPS approaches

GPS approaches

Flight Rules

To put instrument flight rules into context, a brief overview of visual flight rules is neccessary!

Visual Flight Rules

Except special VFR flight, VFR flights shall be conducted so that the aircraft is flown in conditions of visiblity and distance from clouds equal to or greater than those specified in: (VMC)

Visual Meteorological Conitions

Visual Meteorological Conitions

Visual Meteorological Conitions

Lower flight visiblity to 1500m may be permitted for flights operating:

  • at speeds, which will give adequate opportunity to observe the other traffic or any obstacles in time to avoid collision, or

  • in circumstances in which the probability of encourters with other traffic would normally be low e. g. in areas of low volume traffic and for aerial work at low levels.

Visual Meteorological Conitions

Except when a clearance is obtained from an ATC unit, VFR flights shall not take-off or land at an aerodrome within a control zone, or enter the aerodrome traffic zone or traffic pattern:

  • when the ceiling is less than 1500ft
  • when the ground visiblity is less than 5km

Visual Meteorological Conitions

VFR flights shall not be flown:

  • over settlements less than 300m/1000ft above the highest obstacle within a radius of 600m
  • Elsewhere above at a height less than an 150m/500ft

Visual Meteorological Conitions

Special visual flight rules:

  • The ICAO definition of Special VFR flight is a VFR flight cleared by air traffic control to operate within a control zone in meteorological conditions below visual meteorological conditions.
  • Flight under SVFR is only allowed in control zones, and always requires clearance from air traffic control (ATC).

Visual Meteorological Conitions

Special visual flight rules:

  • The aircraft need not necessarily be equipped for flight under IFR, and the aircraft must remain clear of clouds with the surface in sight, and maintain a certain flight visibility minimum (1,500 metres according to ICAO, in sight of surface and clear of cloud in Europe). The pilot continues to be responsible for obstacle and terrain clearance.

Instrument Flight Rules

Instrument Flight Rules

  • When operation of an aircraft under VFR is not safe, because the visual cues outside the aircraft are obscured by weather or darkness, instrument flight rules must be used instead.
  • IFR permits an aircraft to operate in instrument meteorological conditions (IMC), which is essentially any weather condition less than VMC but in which aircraft can still operate safely.
  • Use of instrument flight rules are also required when flying in "Class A" airspace regardless of weather conditions.

Human Factors

One purpose in instrument training and in maintaining instrument proficiency is to prevent us from being misled by several types of hazardous illusions that are peculiar to flight.

Introduction

Knowledge, good judgment, and proficient instrument flying skills are needed to improve statistics and help insure safe flying.

Illusions

In general an illusion or false impression occurs when information provided by our sensory organs is misinterpreted or inadequate.

https://www.youtube.com/watch?v=Rhw9BxBDvzk

Many illusions in flight can be created by compl...

Many illusions in flight can be created by complex motions and certain visual senes that we encounter under adverse weather conditions and at night.

Some illusions may lead to spatial disorientation or the inability to determine accurately the attitude or motion of the aircraft in relation to the Earth's surface. Other illusions may lead to landing errors.

Spatial Disorientation

Spatial disorientation as a result of continued VFR flight into adverse weather conditions is regularly near the top of the cause/factor list in annual statistics on fatal aircraft accidents.

Sensory Systems for Orientation

Parts of the sensory system and the visual system

Parts of the sensory system and the visual system

We use three sensory systems for orientation:

  • the visual system
  • the motion sensing system in the inner ear
  • the position sensing system involving nerves in the skin, muscles, and joints

These systems work together so effectively when we are on the ground that we seldom have any difficulty with orientation.

The visual system

  • Vision is obviously our major sensory organ for orientation while moving about on the ground and during VFR flight.

The visual system

  • Under VFR conditions, aircraft attitude can be determined by observing the Earth's surface, which usually provides accurate and believable visual information.

The visual system

  • However, under IFR conditions, aircraft attitude can only be determined accurately by observing and interpreting the flight instruments.

The motion sensing system

The motion sensing system

https://www.youtube.com/watch?v=dSHnGO9qGsE

The vestibular system:

  • is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance

The motion sensing system

As movements consist of rotations and translations, the vestibular system comprises two components:

  • the semicircular canals, which indicate rotational movements
  • otoliths, which indicate linear accelerations

The motion sensing system

The semicircular canals:

The semicircular canals consist of three tubes at approximate right angles to each other, each located on one of three axes: pitch, roll, or yaw

The motion sensing system

  • Each canal is filled with a fluid called endolymph fluid the center of the canal is the cupola, a gelatinous structure that rests upon sensory hairs located at the end of the vestibular nerves.
  • It is the movement of these hairs within the fluid that causes sensations of motion.

The motion sensing system

Because of the friction between the fluid and the canal, it may take about 15–20 seconds for the fluid in the ear canal to reach the same speed as the canal’s motion.

To illustrate what happens during a turn, visualize the aircraft in straight-and-level flight. With no acceleration of the aircraft, the hair cells are upright, and the body senses that no turn has occurred. Therefore, the position of the hair cells and the actual sensation correspond.

The motion sensing system

  • Placing the aircraft into a turn puts the semicircular canal and its fluid into motion, with the fluid within the semicircular canal lagging behind the accelerated canal walls.
  • This lag creates a relative movement of the fluid within the canal. The canal wall and the cupula move in the opposite direction from the motion of the fluid.

The motion sensing system

  • The brain interprets the movement of the hairs to be a turn in the same direction as the canal wall.
  • The body correctly senses that a turn is being made.
  • If the turn continues at a constant rate for several seconds or longer, the motion of the fluid in the canals catches up with the canal walls.

The motion sensing system

  • The hairs are no longer bent, and the brain receives the false impression that turning has stopped.
  • Thus, the position of the hair cells and the resulting sensation during a prolonged, constant turn in either direction results in the false sensation of no turn!

The motion sensing system

  • When the aircraft returns to straight-and-level flight, the fluid in the canal moves briefly in the opposite direction.
  • This sends a signal to the brain that is falsely interpreted as movement in the opposite direction.
  • In an attempt to correct the falsely perceived turn, the pilot may reenter the turn placing the aircraft in an out-of-control situation.

The motion sensing system

The otolith organs:

  • The otolith organs detect linear acceleration and gravity in a similar way.
  • Instead of being filled with a fluid, a gelatinous membrane containing chalk-like crystals covers the sensory hairs.

The motion sensing system

  • When the pilot tilts his or her head, the weight of these crystals causes this membrane to shift due to gravity, and the sensory hairs detect this shift.
  • The brain orients this new position to what it perceives as vertical. Acceleration and deceleration also cause the membrane to shift in a similar manner.

The motion sensing system

Forward acceleration gives the illusion of the head tilting backward.

As a result, during takeoff and while accelerating, the pilot may sense a steeper than normal climb resulting in a tendency to nose-down.

The position sensing system

The position sensing system

The position sensing system

  • Nerves in the body’s skin, muscles, and joints constantly

send signals to the brain, which signals the body’s relation to

gravity.

  • These signals tell the pilot his or her current position.
  • Acceleration is felt as the pilot is pushed back into the seat
  • https://www.youtube.com/watch?v=S1LA34BYMNo

The position sensing system

  • Forces, created in turns, can lead to false sensations of the true direction of gravity and may give the pilot a false sense of which way is up.
  • Uncoordinated turns, especially climbing turns, can cause misleading signals to be sent to the brain.

The position sensing system

  • Skids and slips give the sensation of banking or tilting. Turbulence can create motions that confuse the brain as well.
  • Pilots need to be aware that fatigue or illness can exacerbate these sensations and ultimately lead to subtle incapacitation.

Illusions Leading to Spatial

Disorientation

Vestibular Illusions

The Leans

The Leans

  • The Leans is the most common type of spatial disorientation for aviators.
  • Through stabilization of the fluid in the semicircular canals, a pilot may perceive straight and level flight when in actuality the plane will be in a balanced turn – Banked turn.
  • This is caused by a quick return to level flight after a gradual, prolonged turn that the pilot failed to notice.

The Leans

  • This illusion is often associated with a vestibulospinal reflex that results in the pilot actually leaning in the direction of the falsely perceived vertical.
  • Other common explanations of the leans are due to deficiencies of both otolith-organ and semicircular-duct sensory mechanisms

The Leans

A condition called “the leans” can result when a banked attitude, to the left for example, may be entered too slowly to set in motion the fluid in the “roll” semicircular tubes.

An abrupt correction of this attitude sets the fluid in motion, creating the illusion of a banked attitude to the right.

The disoriented pilot may make the error of rolling the aircraft into the original left banked attitude, or if level flight is maintained, feel compelled to lean in the perceived vertical plane until this illusion subsides.

Coriolis Illusion

Coriolis Illusion

  • The coriolis illusion occurs when a pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal.
  • A movement of the head in a different plane, such as looking at something in a different part of the flight deck, may set the fluid moving and create the illusion of turning or accelerating on an entirely different axis.

Coriolis Illusion

  • This action causes the pilot to think the aircraft is doing a maneuver that it is not.
  • The disoriented pilot may maneuver the aircraft into a dangerous attitude in an attempt to correct the aircraft’s perceived attitude.

Coriolis Illusion

  • For this reason, it is important that pilots develop an instrument cross-check or scan that involves minimal head movement.
  • Take care when retrieving charts and other objects in the flight deck if something is dropped, retrieve it with minimal head movement and be alert for the coriolis illusion.

Graveyard Spiral

Graveyard Spiral

  • As in other illusions, a pilot in a prolonged coordinated, constant-rate turn, will have the illusion of not turning.
  • During the recovery to level flight, the pilot experiences the sensation of turning in the opposite direction.

Graveyard Spiral

  • The disoriented pilot may return the aircraft to its original turn. Because an aircraft tends to lose altitude in turns unless the pilot compensates for the loss in lift, the pilot may notice a loss of altitude.
  • The absence of any sensation of turning creates the illusion of being in a level descent.

Graveyard Spiral

  • The pilot may pull back on the controls in an attempt to climb or stop the descent.
  • This action tightens the spiral and increases the loss of altitude; hence, this illusion is referred to as a graveyard spiral.
  • At some point, this could lead to a loss of control by the pilot.

Somatogravic Illusion

Somatogravic Illusion

  • A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards.
  • This action creates the somatogravic illusion of being in a nose-up attitude, especially in situations without good visual references.

Somatogravic Illusion

  • The disoriented pilot may push the aircraft into a nose-low or dive attitude.
  • A rapid deceleration by quick reduction of the throttle(s) can have the opposite effect with the disoriented pilot pulling the aircraft into a nose-up or stall attitude.
  • https://www.youtube.com/watch?v=S1LA34BYMNo&t=4s

Inversion Illusion

Inversion Illusion

  • An abrupt change from climb to straight-and-level flight can stimulate the otolith organs enough to create the illusion of tumbling backwards or inversion illusion.
  • The disoriented pilot may push the aircraft abruptly into a nose-low attitude, possibly intensifying this illusion.

Elevator Illusion

Elevator Illusion

  • An abrupt upward vertical acceleration, as can occur in an updraft, can stimulate the otolith organs to create the illusion of being in a climb. This is called elevator illusion.
  • The disoriented pilot may push the aircraft into a nose-low attitude. An abrupt downward vertical acceleration, usually in a downdraft, has the opposite effect with the disoriented pilot pulling the aircraft into a nose-up attitude.

Visual Illusions

  • Visual illusions are especially hazardous because pilots rely on their eyes for correct information.
  • Two illusions that lead to spatial disorientation, false horizon and autokinesis, are concerned with only the visual system.

False Horizon

False Horizon

  • A sloping cloud formation, an obscured horizon, an aurora borealis, a dark scene spread with ground lights and stars, and certain geometric patterns of ground lights can provide inaccurate visual information, or false horizon, for aligning the aircraft correctly with the actual horizon.
  • The disoriented pilot may place the aircraft in a dangerous attitude.

Autokinesis

Autokinesis

  • In the dark, a stationary light will appear to move about when stared at for many seconds.
  • The disoriented pilot could lose control of the aircraft in attempting to align it with the false movements of this light called autokinesis.

Postural Considerations

Postural Considerations

  • The postural system sends signals from the skin, joints, and muscles to the brain that are interpreted in relation to the Earth’s gravitational pull.
  • These signals determine posture. Inputs from each movement update the body’s position to the brain on a constant basis.
  • “Seat of the pants” flying is largely dependent upon these signals.

Postural Considerations

  • Used in conjunction with visual and vestibular clues, these sensations can be fairly reliable.
  • However, because of the forces acting upon the body in certain flight situations, many false sensations can occur due to acceleration forces overpowering gravity.
  • These situations include uncoordinated turns, climbing turns, and turbulence.

Coping with Spatial Disorientation

Coping with Spatial Disorientation

To prevent illusions and their potentially disastrous consequences, pilots can:

  • Understand the causes of these illusions and remain constantly alert for them. Take the opportunity to understand and then experience spatial disorientation illusions in a device, such as a Barany chair, a Vertigon, or a Virtual Reality Spatial Disorientation Demonstrator.
  • Always obtain and understand preflight weather briefings.

Coping with Spatial Disorientation

  • Before flying in marginal visibility (less than 3 miles) or where a visible horizon is not evident such as flight over open water during the night, obtain training and maintain proficiency in airplane control by reference to instruments.
  • Do not continue flight into adverse weather conditions or into dusk or darkness unless proficient in the use of flight instruments. If intending to fly at night, maintain night-flight currency and proficiency. Include cross- country and local operations at various airfields.

Coping with Spatial Disorientation

  • Ensure that when outside visual references are used, they are reliable, fixed points on the Earth’s surface.
  • Avoid sudden head movement, particularly during takeoffs, turns, and approaches to landing.
  • Be physically tuned for flight into reduced visibility. Ensure proper rest, adequate diet, and, if flying at night, allow for night adaptation. Remember that illness, medication, alcohol, fatigue, sleep loss, and mild hypoxia are likely to increase susceptibility to spatial disorientation.

Coping with Spatial Disorientation

  • Most importantly, become proficient in the use of flight instruments and rely upon them. Trust the instruments and disregard your sensory perceptions.

Coping with Spatial Disorientation

The sensations that lead to illusions during instrument flight conditions are normal perceptions experienced by pilots. These undesirable sensations cannot be completely prevented, but through training and awareness, pilots can ignore or suppress them by developing absolute reliance on the flight instruments. As pilots gain proficiency in instrument flying, they become less susceptible to these illusions and their effects.

Optical Illusions

Introduction

Introduction

  • Of the senses, vision is the most important for safe flight.
  • However, various terrain features and atmospheric conditions can create optical illusions.
  • These illusions are primarily associated with landing.
  • Since pilots must transition from reliance on instruments to visual cues outside the flight deck for landing at the end of an instrument approach, it is imperative they be aware of the potential problems associated with these illusions and take appropriate corrective action.

Runway Width Illusion

Runway Width Illusion

  • A narrower-than-usual runway can create an illusion the aircraft is at a higher altitude than it actually is, especially when runway length-to-width relationships are comparable.
  • The pilot who does not recognize this illusion will fly a lower approach with the risk of striking objects along the approach path or landing short.

Runway Width Illusion

  • A wider-than-usual runway can have the opposite effect with the risk of leveling out high and landing hard or overshooting the runway.

Runway and Terrain Slopes Illusion

Runway and Terrain Slopes Illusion

  • An upsloping runway, upsloping terrain, or both can create an illusion the aircraft is at a higher altitude than it actually is.
  • The pilot who does not recognize this illusion will fly a lower approach.

Runway and Terrain Slopes Illusion

  • Downsloping runways and downsloping approach terrain can have the opposite effect. Downsloping runways can create an illusion the aircraft is a lower altitude than it actually is.
  • The pilot who does not recognize this illusion will fly a higher approach.

Further type of illusions

Further type of illusions

1, Featureless Terrain Illusion:

  • An absence of surrounding ground features, as in an overwater approach, over darkened areas, or terrain made featureless by snow, can create an illusion the aircraft is at a higher altitude than it actually is.
  • This illusion, sometimes referred to as the “black hole approach,” causes pilots to fly a lower approach than is desired.

Featureless Terrain Illusion

Further type of illusions

2, Water Refraction:

  • Rain on the windscreen can create an illusion of being at a higher altitude due to the horizon appearing lower than it is.
  • This can result in the pilot flying a lower approach.

Further type of illusions

3, Haze:

  • Atmospheric haze can create an illusion of being at a greater distance and height from the runway.
  • As a result, the pilot has a tendency to be low on the approach. Conversely, extremely clear air (clear bright conditions of a high attitude airport) can give the pilot the illusion of being closer than he or she actually is, resulting in a high approach that may cause an overshoot or go around.

Haze

  • The diffusion of light due to water particles on the windshield can adversely affect depth perception.
  • The lights and terrain features normally used to gauge height during landing become less effective for the pilot.

Further type of illusions

4, Fog:

  • Flying into fog can create an illusion of pitching up. Pilots who do not recognize this illusion often steepen the approach quite abruptly.

Further type of illusions

5, Ground Lighting Illusions:

  • Lights along a straight path, such as a road or lights on moving trains, can be mistaken for runway and approach lights.
  • Bright runway and approach lighting systems, especially where few lights illuminate the surrounding terrain, may create the illusion of less distance to the runway.
  • The pilot who does not recognize this illusion will often fly a higher approach.

Ground Lighting Illusions

How To Prevent Landing Errors Due to Optical Illusions

To prevent these illusions and their potentially hazardous consequences, pilots can:

How To Prevent Landing Errors Due to Optical Illusions

How To Prevent Landing Errors Due to Optical Illusions

How To Prevent Landing Errors Due to Optical Illusions

  • Anticipate the possibility of visual illusions during approaches to unfamiliar airports, particularly at night or in adverse weather conditions. Consult airport diagrams and the Airport/Facility Directory (A/FD) for information on runway slope, terrain, and lighting.
  • Make frequent reference to the altimeter, especially during all approaches, day and night.
  • If possible, conduct aerial visual inspection of unfamiliar airports before landing.

How To Prevent Landing Errors Due to Optical Illusions

  • Use Visual Approach Slope Indicator (VASI) or Precision Approach Path Indicator (PAPI) systems for a visual reference or an electronic glideslope, whenever they are available.
  • Utilize the visual descent point (VDP) found on many nonprecision instrument approach procedure charts.
  • Recognize that the chances of being involved in an approach accident increase when some emergency or other activity distracts from usual procedures.
  • Maintain optimum proficiency in landing procedures.

Aerodynamic Factors

Introduction

Introduction

  • Several factors affect aircraft performance including the atmosphere, aerodynamics, and aircraft icing.
  • Pilots need an understanding of these factors for a sound basis for prediction of aircraft response to control inputs, especially with regard to instrument approaches, while holding, and when operating at reduced airspeed in instrument meteorological conditions (IMC).

Introduction

  • Although these factors are important to the pilot flying visual flight rules (VFR), they must be even more thoroughly understood by the pilot operating under instrument flight rules (IFR).
  • Instrument pilots rely strictly on instrument indications to precisely control the aircraft; therefore, they must have a solid understanding of basic aerodynamic principles in order to make accurate judgments regarding aircraft control inputs.

Review of basic aerodnamics

Definitions and Laws

Definitions and Laws

  • The instrument pilot must understand the relationship and differences between several factors that affect the performance of an aircraft in flight. Also, it is crucial to understand how the aircraft reacts to various control and power changes, because the environment in which instrument pilots fly has inherent hazards not found in visual flying.
  • The basis for this understanding is found in the four forces acting on an aircraft and Newton’s Three Laws of Motion.

Angle of attack and relative wind

  • Relative Wind is the direction of the airflow with respect to an airfoil.
  • Angle of Attack (AOA) is the acute angle measured between the relative wind, or flightpath and the chord of the airfoil.
  • Flightpath is the course or track along which the aircraft is

flying or is intended to be flown.

The Four Forces

The four basic forces acting upon an aircraft in flight are lift, weight, thrust, and drag.

Lift

  • Lift is a component of the total aerodynamic force on an airfoil and acts perpendicular to the relative wind.
  • Relative wind is the direction of the airflow with respect to an airfoil.
  • This force acts straight up from the average (called mean) center of pressure (CP), which is called the center of lift.
  • It should be noted that it is a point along the chord line of an airfoil through which all aerodynamic forces are considered to act.
  • The magnitude of lift varies proportionately with speed, air density, shape and size of the airfoil, and AOA. During straight-and-level flight, lift and weight are equal.

Weight

  • Weight is the force exerted by an aircraft from the pull of gravity. It acts on an aircraft through its center of gravity (CG) and is straight down.
  • This should not be confused with the center of lift, which can be significantly different from the CG. As an aircraft is descending, weight is greater than lift.

Thrust

  • Thrust is the forward force produced by the powerplant/ propeller or rotor. It opposes or overcomes the force of drag.
  • As a general rule, it acts parallel to the longitudinal axis.

Drag

Drag is the net aerodynamic force parallel to the relative wind and is generally a sum of two components: induced drag and parasite drag.

Drag

Induced Drag:

  • Induced drag is caused from the creation of lift and increases with AOA.
  • Therefore, if the wing is not producing lift, induced drag is zero. Conversely, induced drag decreases with airspeed.

Drag

Parasite Drag:

  • Parasite drag is all drag not caused from the production of lift.
  • Parasite drag is created by displacement of air by the aircraft, turbulence generated by the airfoil, and the hindrance of airflow as it passes over the surface of the aircraft or components.
  • All of these forces create drag not from the production of lift but the movement of an object through an air mass.
  • Parasite drag increases with speed and includes skin friction drag, interference drag, and form drag.

Newton's Laws

Newton’s First Law, the Law of Inertia

  • Newton’s First Law of Motion is the Law of Inertia.
  • It states that a body at rest will remain at rest, and a body in motion will remain in motion, at the same speed and in the same direction until affected by an outside force.
  • The force with which a body offers resistance to change is called the force of inertia.

Newton’s First Law

  • Two outside forces are always present on an aircraft in flight: gravity and drag.
  • The pilot uses pitch and thrust controls to counter or change these forces to maintain the desired flightpath.
  • If a pilot reduces power while in straight- and-level flight, the aircraft will slow due to drag.
  • However, as the aircraft slows there is a reduction of lift, which causes the aircraft to begin a descent due to gravity.

Newton's Laws

Newton’s Second Law, the Law of Momentum

  • Newton’s Second Law of Motion is the Law of Momentum, which states that a body will accelerate in the same direction as the force acting upon that body, and the acceleration will be directly proportional to the net force and inversely proportional to the mass of the body.
  • Acceleration refers either to an increase or decrease in velocity, although deceleration is commonly used to indicate a decrease. This law governs the aircraft’s ability to change flightpath and speed, which are controlled by attitude (both pitch and bank) and thrust inputs.
  • Speeding up, slowing down, entering climbs or descents, and turning are examples of accelerations that the pilot controls in everyday flight.

Newton’s Second Law, the Law of Momentum

Newton’s Third Law, the Law of Reaction

  • Newton’s Third Law of Motion is the Law of Reaction, which states that for every action there is an equal and opposite reaction.
  • As shown in, the action of the jet engine’s thrust or the pull of the propeller lead to the reaction of the aircraft’s forward motion.
  • This law is also responsible for a portion of the lift that is produced by a wing, from the downward deflection of the airflow around it. This downward force of the relative wind results in an equal but opposite (upward) lifting force created by the airflow over the wing.

Atmosphere

Atmosphere

  • The atmosphere is the envelope of air which surrounds the Earth.
  • A given volume of dry air contains about 78 percent nitrogen, 21 percent oxygen, and about 1 percent other gases such as argon, carbon dioxide, and others to a lesser degree.

Atmosphere

  • Air density is a result of the relationship between temperature and pressure.
  • Air density is inversely related to temperature and directly related to pressure.
  • For a constant pressure to be maintained as temperature increases, density must decrease, and vice versa.
  • For a constant temperature to be maintained as pressure increases, density must increase, and vice versa.
  • These relationships provide a basis for understanding instrument indications and aircraft performance.

Layers of the Atmosphere

  • There are several layers to the atmosphere with the troposphere being closest to the Earth’s surface extending to about 60,000 feet at the equator.
  • Following is the stratosphere, mesosphere, ionosphere, thermosphere, and finally the exosphere.
  • The tropopause is the thin layer between the troposphere and the stratosphere.
  • It varies in both thickness and altitude but is generally defined where the standard lapse (generally accepted at 2 °C per 1,000 feet) decreases significantly (usually down to 1 °C or less).

International Standard Atmosphere (ISA)

  • The International Civil Aviation Organization (ICAO) established the ICAO Standard Atmosphere as a way of creating an international standard for reference and performance computations.
  • Instrument indications and aircraft performance specifications are derived using this standard as a reference.
  • Because the standard atmosphere is a derived set of conditions that rarely exist in reality, pilots need to understand how deviations from the standard affect both instrument indications and aircraft performance.

International Standard Atmosphere

  • In the standard atmosphere, sea level pressure is 1013,25 hPa and the temperature is 15 °C. The standard lapse rate for pressure is approximately a 1 Hg/33,86 hPa decrease per 1,000 feet increase in altitude.
  • The standard lapse rate for temperature is a 2 °C decrease per 1,000 feet increase, up to the top of the stratosphere.
  • Since all aircraft performance is compared and evaluated in the environment of the standard atmosphere, all aircraft performance instrumentation is calibrated for the standard atmosphere.
  • Because the actual operating conditions rarely, if ever, fit the standard atmosphere, certain corrections must apply to the instrumentation and aircraft performance.

International Standard Atmosphere

  • If the temperature or the pressure is different than the International Standard Atmosphere (ISA) prediction an adjustment must be made to performance predictions and various instrument indications.

Pressure Altitude

  • Pressure altitude is the height above the standard datum plane (SDP). The aircraft altimeter is essentially a sensitive barometer calibrated to indicate altitude in the standard atmosphere.
  • If the altimeter is set for 1013,25 hPa SDP, the altitude indicated is the standard pressure altitude (FL) the altitude in the standard atmosphere corresponding to the sensed pressure.

Density Altitude

  • Density altitude is pressure altitude corrected for nonstandard temperature. As the density of the air increases (lower density altitude), aircraft performance increases.
  • Conversely, as air density decreases (higher density altitude), aircraft performance decreases.
  • A decrease in air density means a high density altitude; an increase in air density means a lower density altitude.
  • Density altitude is used in calculating aircraft performance. Under standard atmospheric conditions, air at each level in the atmosphere has a specific density; under standard conditions, pressure altitude and density altitude identify the same level.
  • Density altitude, then, is the vertical distance above sea level in the standard atmosphere at which a given density is to be found.

Density Altitude

  • It can be computed using a Koch Chart or a flight computer with a density altitude function.
  • If a chart is not available, the density altitude can be estimated by adding 120 feet for every degree Celsius above the ISA.
  • For example, at 3,000 feet PA, the ISA prediction is 9 °C (15 °C – [lapse rate of 2 °C per 1,000 feet x 3 = 6 °C]). However, if the actual temperature is 20 °C (11 °C more than that predicted by ISA) then the difference of 11 °C is multiplied by 120 feet equaling 1,320. Adding this figure to the original 3,000 feet provides a density altitude of 4,320 feet (3,000 feet + 1,320 feet).

Drag Curves

Introduction

Introduction

When induced drag and parasite drag are plotted on a graph, the total drag on the aircraft appears in the form of a “drag curve.”

Introduction

  • Understanding the drag curve can provide valuable insight into the various performance parameters and limitations of the aircraft.
  • Because power must equal drag to maintain a steady airspeed, the curve can be either a drag curve or a power required curve.
  • The power required curve represents the amount of power needed to overcome drag in order to maintain a steady speed in level flight.

Introduction

  • The propellers used on most reciprocating engines achieve peak propeller efficiencies in the range of 80 to 88 percent.
  • As airspeed increases, the propeller efficiency increases until it reaches its maximum.
  • Any airspeed above this maximum point causes a reduction in propeller efficiency.
  • An engine that produces 160 horsepower will have only about 80 percent of that power converted into available horsepower, approximately 128 horsepower.
  • The remainder is lost energy. This is the reason the thrust and power available curves change with speed.

Regions of Command

Regions of Command

  • The drag curve also illustrates the two regions of command: the region of normal command, and the region of reversed command.
  • The term “region of command” refers to the relationship between speed and the power required to maintain or change that speed.
  • “Command” refers to the input the pilot must give in terms of power or thrust to maintain a new speed once reached.

Regions of Command

  • The “region of normal command” occurs where power must be added to increase speed.
  • This region exists at speeds higher than the minimum drag point primarily as a result of parasite drag.

Regions of Command

  • The “region of reversed command” occurs where additional power is needed to maintain a slower airspeed.
  • This region exists at speeds slower than the minimum drag point (L/DMAX on the thrust required curve) and is primarily due to induced drag.

Regions of Command

  • Figure shows how one power setting can yield two speeds, points 1 and 2.
  • This is because at point 1 there is high induced drag and low parasite drag, while at point 2 there is high parasite drag and low induced drag.

Control Characteristics

  • Most flying is conducted in the region of normal command: for example, cruise, climb, and maneuvers.
  • The region of reversed command may be encountered in the slow-speed phases of flight during takeoff and landing; however, for most general aviation aircraft, this region is very small and is below normal approach speeds.

Control Characteristics

  • Flight in the region of normal command is characterized by a relatively strong tendency of the aircraft to maintain the trim speed.
  • Flight in the region of reversed command is characterized by a relatively weak tendency of the aircraft to maintain the trim speed.

Control Characteristics

  • In fact, it is likely the aircraft exhibits no inherent tendency to maintain the trim speed in this area.
  • For this reason, the pilot must give particular attention to precise control of airspeed when operating in the slow-speed phases of the region of reversed command.

Control Characteristics

  • Operation in the region of reversed command does not imply that great control difficulty and dangerous conditions exist.
  • However, it does amplify errors of basic flying technique making proper flying technique and precise control of the aircraft very important.

Speed Stability

Normal Command

Normal Command

  • The characteristics of flight in the region of normal command are illustrated at point A on the curve in the Figure If the aircraft is established in steady, level flight at point A, lift is equal to weight, and the power available is set equal to the power required.

Normal Command

  • If the airspeed is increased with no changes to the power setting, a power deficiency exists.
  • The aircraft has a natural tendency to return to the initial speed to balance power and drag.
  • If the airspeed is reduced with no changes to the power setting, an excess of power exists.
  • The aircraft has a natural tendency to speed up to regain the balance between power and drag.

Normal Command

  • Keeping the aircraft in proper trim enhances this natural tendency.
  • The static longitudinal stability of the aircraft tends to return the aircraft to the original trimmed condition. An aircraft flying in steady, level flight at point C is in equilibrium.
  • If the speed were increased or decreased slightly, the aircraft would tend to remain at that speed.

Normal Command

  • This is because the curve is relatively flat and a slight change in speed does not produce any significant excess or deficiency in power.
  • It has the characteristic of neutral stability (i.e., the aircraft’s tendency is to remain at the new speed).

Reserved Command

Reserved Command

  • The characteristics of flight in the region of reversed command are illustrated at point B on the curve in the Figure.
  • If the aircraft is established in steady, level flight at point B, lift is equal to weight, and the power available is set equal to the power required.

Reserved Command

  • When the airspeed is increased greater than point B, an excess of power exists.
  • This causes the aircraft to accelerate to an even higher speed.
  • When the aircraft is slowed to some airspeed lower than point B, a deficiency of power exists.
  • The natural tendency of the aircraft is to continue to slow to an even lower airspeed.

Reserved Command

  • This tendency toward instability happens because the variation of excess power to either side of point B magnifies the original change in speed.
  • Although the static longitudinal stability of the aircraft tries to maintain the original trimmed condition, this instability is more of an influence because of the increased induced drag due to the higher AOA in slow- speed flight.

Trim

Trim

  • The term trim refers to employing adjustable aerodynamic devices on the aircraft to adjust forces so the pilot does not have to manually hold pressure on the controls.
  • One means is to employ trim tabs.

Trim

  • A trim tab is a small, adjustable hinged surface, located on the trailing edge of the elevator, aileron, or rudder control surfaces. (Some aircraft use adjustable stabilizers instead of trim tabs for pitch trim.)

Trim

  • Trimming is accomplished by deflecting the tab in the direction opposite to that in which the primary control surface must be held.
  • The force of the airflow striking the tab causes the main control surface to be deflected to a position that corrects the unbalanced condition of the aircraft.

Trim

  • Because the trim tabs use airflow to function, trim is a function of speed.
  • Any change in speed results in the need to re-trim the aircraft. An aircraft properly trimmed in pitch seeks to return to the original speed before the change.

Trim

  • It is very important for instrument pilots to keep the aircraft in constant trim.
  • This reduces the pilot’s workload significantly, allowing attention to other duties without compromising aircraft control.

http://www.boldmethod.com/learn-to-fly/systems/4-types-of-trim-tabs/

Trim

Trim

Trim

Trim

Slow speed flight

Introduction

Introduction

Anytime an aircraft is flying near the stalling speed or the region of reversed command, such as in final approach for a normal landing, the initial part of a go around, or maneuvering in slow flight, it is operating in what is called slow-speed flight.

Introduction

Because the same lift is required during low speed flight and is characterized by high AOA, flaps or other high lift devices are needed to either change the camber of the airfoil, or delay the boundary level separation.

Cl can be increased by increasing of AOA

Introduction

It should be noted that with the application of flaps, the aircraft will stall at a lower AOA.

  • For example, if the basic wing stalls at 18° without flaps, then with the addition of flaps to the CL-MAX position, the new AOA that the wing will stall is 15°.
  • However, the value of lift (flaps extended to the CL-MAX position) produces more lift than lift at 18° on the basic wing.

Introduction

  • Delaying the boundary layer separation is another way to

increase CL-MAX.

  • Several methods are employed, but the most common device used on general aviation light aircraft is the vortex generator.
  • Small strips of metal placed along the wing (usually in front of the control surfaces) create turbulence.
  • The turbulence in turn mixes high energy air from outside the boundary layer with boundary layer air.
  • The effect is similar to other boundary layer devices.

Small airplanes

Small airplanes

  • Most small airplanes maintain a speed well in excess of 1.3 times VSO on an instrument approach.
  • An airplane with a stall speed of 50 knots (VSO) has a normal approach speed of 65 knots.
  • However, this same airplane may maintain 90 knots (1.8 VSO) while on the final segment of an instrument approach.

Small airplanes

  • The landing gear will most likely be extended at the beginning of the descent to the minimum descent altitude, or upon intercepting the glideslope of the instrument landing system.
  • The pilot may also select an intermediate flap setting for this phase of the approach.
  • The airplane at this speed has good positive speed stability, as represented by point A on the Figure

Small airplanes

  • Flying in this regime permits the pilot to make slight pitch changes without changing power settings, and accept minor speed changes knowing that when the pitch is returned to the initial setting, the speed returns to the original setting.
  • This reduces the pilot’s workload.

Small airplanes

  • Aircraft are usually slowed to a normal landing speed when on the final approach just prior to landing. When slowed to 65 knots, (1.3 VSO), the airplane will be close to point C.
  • At this point, precise control of the pitch and power becomes more crucial for maintaining the correct speed.

Small airplanes

  • Pitch and power coordination is necessary because the speed stability is relatively neutral since the speed tends to remain at the new value and not return to the original setting.
  • In addition to the need for more precise airspeed control, the pilot normally changes the aircraft’s configuration by extending landing flaps.
  • This configuration change means the pilot must be alert to unwanted pitch changes at a low altitude.

Small airplanes

  • If allowed to slow several knots, the airplane could enter the region of reversed command.
  • At this point, the airplane could develop an unsafe sink rate and continue to lose speed unless the pilot takes a prompt corrective action.
  • Proper pitch and power coordination is critical in this region due to speed instability and the tendency of increased divergence from the desired speed.

Large airplanes

Large airplanes

  • Pilots of larger airplanes with higher stall speeds may find the speed they maintain on the instrument approach is near 1.3 VSO, putting them near point the entire time the airplane is on the final approach segment.
  • In this case, precise speed control is necessary throughout the approach.
  • It may be necessary to temporarily select excessive, or deficient thrust in relation to the target thrust setting in order to quickly correct for airspeed deviations.

Large airplanes

  • For example, a pilot is on an instrument approach at 1.3 VSO, a speed near L/DMAX, and knows that a certain power setting maintains that speed.
  • The airplane slows several knots below the desired speed because of a slight reduction in the power setting.
  • The pilot increases the power slightly, and the airplane begins to accelerate, but at a slow rate.

Large airplanes

  • Because the airplane is still in the “flat part” of the drag curve, this slight increase in power will not cause a rapid return to the desired speed.
  • The pilot may need to increase the power higher than normally needed to maintain the new speed, allow the airplane to accelerate, then reduce the power to the setting that maintains the desired speed.

Turns

Introduction

Introduction

  • Like any moving object, an aircraft requires a sideward force to make it turn.
  • In a normal turn, this force is supplied by banking the aircraft in order to exert lift inward, as well as upward.
  • The force of lift is separated into two components at right angles to each other.

Introduction

  • The upward acting lift together with the opposing weight becomes the vertical lift component.
  • The horizontally acting lift and its opposing centrifugal force are the horizontal lift component, or centripetal force.
  • This horizontal lift component is the sideward force that causes an aircraft to turn.
  • The equal and opposite reaction to this sideward force is centrifugal force, which is merely an apparent force as a result of inertia.

Introduction

  • The relationship between the aircraft’s speed and bank angle to the rate and radius of turns is important for instrument pilots to understand.
  • The pilot can use this knowledge to properly estimate bank angles needed for certain rates of turn, or to determine how much to lead when intercepting a course.

Rate of Turn

Rate of Turn

  • The rate of turn, normally measured in degrees per second, is based upon a set bank angle at a set speed.
  • If either one of these elements changes, the rate of turn changes.

Rate of Turn

  • If the aircraft increases its speed without changing the bank angle, the rate of turn decreases.
  • Likewise, if the speed decreases without changing the bank angle, the rate of turn increases.
  • Changing the bank angle without changing speed also causes the rate of turn to change.
  • Increasing the bank angle without changing speed increases the rate of turn, while decreasing the bank angle reduces the rate of turn.

Rate of Turn

  • The standard rate of turn, 3° per second, is used as the main reference for bank angle.
  • Therefore, the pilot must understand how the angle of bank varies with speed changes, such as slowing down for holding or an instrument approach.

Rate of Turn

  • The Figure shows the turn relationship with reference to a constant bank angle or a constant airspeed, and the effects on rate of turn and radius of turn.
  • A rule of thumb for determining the standard rate turn is to divide the airspeed by ten and add 7. An aircraft with an airspeed of 90 knots takes a bank angle of 16° to maintain a standard rate turn (90 divided by 10 plus 7 equals 16°).

Radius of Turn

Radius of Turn

  • The radius of turn varies with changes in either speed or bank. If the speed is increased without changing the bank angle, the radius of turn increases, and vice versa.
  • If the speed is constant, increasing the bank angle reduces the radius of turn, while decreasing the bank angle increases the radius of turn.

Radius of Turn

  • This means that intercepting a course at a higher speed requires more distance, and therefore, requires a longer lead.
  • If the speed is slowed considerably in preparation for holding or an approach, a shorter lead is needed than that required for cruise flight.

Coordination of Rudder and Aileron Controls

Coordination of Rudder and Aileron Controls

Any time ailerons are used, adverse yaw is produced. Adverse yaw is caused when the ailerons are deflected as a roll motion (as in turn) is initiated.

Coordination of Rudder and Aileron Controls

  • In a right turn, the right aileron is deflected upward while the left is deflected downward.
  • Lift is increased on the left side and reduced on the right, resulting in a bank to the right.
  • However, as a result of producing lift on the left, induced drag is also increased on the left side.

Coordination of Rudder and Aileron Controls

  • The drag causes the left wing to slow down, in turn causing the nose of the aircraft to initially move (left) in the direction opposite of the turn.
  • Correcting for this yaw with rudder, when entering and exiting turns, is necessary for precise control of the airplane when flying on instruments.
  • The pilot can tell if the turn is coordinated by checking the ball in the turn-and- slip indicator or the turn coordinator.

Coordination of Rudder and Aileron Controls

  • As the aircraft banks to enter a turn, a portion of the wing’s vertical lift becomes the horizontal component; therefore, without an increase in back pressure, the aircraft loses altitude during the turn.
  • The loss of vertical lift can be offset by increasing the pitch in one-half bar width increments.
  • Trim may be used to relieve the control pressures; however, if used, it has to be removed once the turn is complete.

Coordination of Rudder and Aileron Controls

  • In a slipping turn, the aircraft is not turning at the rate appropriate to the bank being used, and the aircraft falls to the inside of the turn.
  • The aircraft is banked too much for the rate of turn, so the horizontal lift component is greater than the centrifugal force.
  • A skidding turn results from excess of centrifugal force over the horizontal lift component, pulling the aircraft toward the outside of the turn.
  • The rate of turn is too great for the angle of bank, so the horizontal lift component is less than the centrifugal force.

Coordination of Rudder and Aileron Controls

  • An inclinometer, located in the turn coordinator, or turn and bank indicator indicates the quality of the turn, and should be centered when the wings are banked.
  • If the ball is off of center on the side toward the turn, the aircraft is slipping and rudder pressure should be added on that side to increase the rate of turn or the bank angle should be reduced.
  • If the ball is off of center on the side away from the turn, the aircraft is skidding and rudder pressure toward the turn should be relaxed or the bank angle should be increased.
  • If the aircraft is properly rigged, the ball should be in the center when the wings are level; use rudder and/or aileron trim if available.

Coordination of Rudder and Aileron Controls

Coordination of Rudder and Aileron Controls

The increase in induced drag, caused by the increase in AOA necessary to maintain altitude results in a minor loss of airspeed if the power setting is not changed.

Load Factor

Load Factor

Any force applied to an aircraft to deflect its flight from a straight line produces a stress on its structure; the amount of this force is termed load factor. A load factor is the ratio of the aerodynamic force on the aircraft to the gross weight of the aircraft (e.g., lift/weight).

Load Factor

  • For example, a load factor of 3 means the total load on an aircraft’s structure is three times its gross weight.
  • When designing an aircraft, it is necessary to determine the highest load factors that can be expected in normal operation under various operational situations. These “highest” load factors are called “limit load factors.”

Load Factor

  • The specified load may be expected in terms of aerodynamic forces, as in turns.
  • In level flight in undisturbed air, the wings are supporting not only the weight of the aircraft, but centrifugal force as well.
  • As the bank steepens, the horizontal lift component increases, centrifugal force increases, and the load factor increases.

Load Factor

  • If the load factor becomes so great that an increase in AOA cannot provide enough lift to support the load, the wing stalls.
  • Since the stalling speed increases directly with the square root of the load factor, the pilot should be aware of the flight conditions during which the load factor can become critical.
  • Steep turns at slow airspeed, structural ice accumulation, and vertical gusts in turbulent air can increase the load factor to a critical level.

Icing

Introduction

Introduction

One of the greatest hazards to flight is aircraft icing. The instrument pilot must be aware of the conditions conducive to aircraft icing. These conditions include the types of icing, the effects of icing on aircraft control and performance, effects of icing on aircraft systems, and the use and limitations of aircraft deice and anti-ice equipment.

Introduction

  • Coping with the hazards of icing begins with preflight planning to determine where icing may occur during a flight and ensuring the aircraft is free of ice and frost prior to takeoff.
  • This attention to detail extends to managing deice and anti-ice systems properly during the flight, because weather conditions may change rapidly, and the pilot must be able to recognize when a change of flight plan is required.

Types of Icing

Structural Icing

Structural Icing

  • Structural icing refers to the accumulation of ice on the exterior of the aircraft. Ice forms on aircraft structures and surfaces when super-cooled droplets impinge on them and freeze.
  • Small and/or narrow objects are the best collectors of droplets and ice up most rapidly.

Structural Icing

  • This is why a small protuberance within sight of the pilot can be used as an “ice evidence probe.”
  • It is generally one of the first parts of the airplane on which an appreciable amount of ice forms.
  • An aircraft’s tailplane is a better collector than its wings, because the tailplane presents a thinner surface to the airstream.

Induction Icing

Induction Icing

Ice in the induction system can reduce the amount of air available for combustion. The most common example of reciprocating engine induction icing is carburetor ice.

Induction Icing

  • Most pilots are familiar with this phenomenon, which occurs when moist air passes through a carburetor venturi and is cooled.
  • As a result of this process, ice may form on the venturi walls and throttle plate, restricting airflow to the engine. This may occur at temperatures between –7 °C and 21 °C.

Induction Icing

  • The problem is remedied by applying carburetor heat, which uses the engine’s own exhaust as a heat source to melt the ice or prevent its formation.
  • On the other hand, fuel-injected aircraft engines usually are less vulnerable to icing but still can be affected if the engine’s air source becomes blocked with ice.
  • Manufacturers provide an alternate air source that may be selected in case the normal system malfunctions.

Types of ice by formation

Types of ice by formation

  • The type of ice that forms can be classified as clear, rime, or mixed, based on the structure and appearance of the ice.
  • The type of ice that forms varies depending on the atmospheric and flight conditions in which it forms.
  • Significant structural icing on an aircraft can cause serious aircraft control and performance problems.

Clear Ice

  • A glossy, transparent ice formed by the relatively slow freezing of super cooled water is referred to as clear ice.
  • The terms “clear” and “glaze” have been used for essentially the same type of ice accretion.

Clear Ice

  • This type of ice is denser, harder, and sometimes more transparent than rime ice.
  • With larger accretions, clear ice may form “horns.”
  • Temperatures close to the freezing point, large amounts of liquid water, high aircraft velocities, and large droplets are conducive to the formation of clear ice.

Rime Ice

  • A rough, milky, opaque ice formed by the instantaneous or very rapid freezing of super cooled droplets as they strike the aircraft is known as rime ice.
  • The rapid freezing results in the formation of air pockets in the ice, giving it an opaque appearance and making it porous and brittle. For larger accretions, rime ice may form a streamlined extension of the wing.
  • Low temperatures, lesser amounts of liquid water, low velocities, and small droplets are conducive to the formation of rime ice.

Mixed Ice

Mixed ice is a combination of clear and rime ice formed on the same surface. It is the shape and roughness of the ice that is most important from an aerodynamic point of view.

General Effects of Icing on Airfoils

Introduction

Introduction

  • The most hazardous aspect of structural icing is its aerodynamic effects.
  • Ice alters the shape of an airfoil, reducing the maximum coefficient of lift and AOA at which the aircraft stalls.
  • Note that at very low AOAs, there may be little or no effect of the ice on the coefficient of lift. Therefore, when cruising at a low AOA, ice on the wing may have little effect on the lift.

Introduction

  • However, note that the ice significantly reduces the CL-MAX, and the AOA at which it occurs (the stall angle) is much lower.
  • Thus, when slowing down and increasing the AOA for approach, the pilot may find that ice on the wing, which had little effect on lift in cruise now, causes stall to occur at a lower AOA and higher speed.

Introduction

  • Even a thin layer of ice at the leading edge of a wing, especially if it is rough, can have a significant effect in increasing stall speed.
  • For large ice shapes, especially those with horns, the lift may also be reduced at a lower AOA.
  • The accumulation of ice affects the coefficient of drag of the airfoil. Note that the effect is significant even at very small AOAs.

Introduction

  • A significant reduction in CL-MAX and a reduction in the AOA where stall occurs can result from a relatively small ice accretion.
  • A reduction of CL-MAX by 30 percent is not unusual, and a large horn ice accretion can result in reductions of 40 percent to 50 percent.
  • Drag tends to increase steadily as ice accretes.
  • An airfoil drag increase of 100 percent is not unusual, and for large horn ice accretions, the increase can be 200 percent or even higher.

Introduction

  • Most aircraft have a nose-down pitching moment from the wings because the CG is ahead of the CP.
  • It is the role of the tailplane to counteract this moment by providing a downward force. The result of this configuration is that actions which move the wing away from stall, such as deployment of flaps or increasing speed, may increase the negative AOA of the tail.
  • With ice on the tailplane, it may stall after full or partial deployment of flaps.

Introduction

  • Since the tailplane is ordinarily thinner than the wing, it is a more efficient collector of ice.
  • On most aircraft the tailplane is not visible to the pilot, who therefore cannot observe how well it has been cleared of ice by any deicing system.
  • Thus, it is important that the pilot be alert to the possibility of tailplane stall, particularly on approach and landing.

Tailplane Stall Symptoms

Tailplane Stall Symptoms

Any of the following symptoms, occurring singly or in combination, may be a warning of tailplane icing:

  • Elevator control pulsing, oscillations, or vibrations;
  • Abnormal nose-down trim change;
  • Any other unusual or abnormal pitch anomalies (possibly resulting in pilot induced oscillations);
  • Reduction or loss of elevator effectiveness;
  • Sudden change in elevator force (control would move nose-down if unrestrained); and
  • Sudden uncommanded nose-down pitch.

Tailplane Stall Symptoms

If any of the above symptoms occur, the pilot should:

  • Immediately retract the flaps to the previous setting and apply appropriate nose-up elevator pressure;
  • Increase airspeed appropriately for the reduced flap extension setting;
  • Apply sufficient power for aircraft configuration and conditions. (High engine power settings may adversely impact response to tailplane stall conditions at high airspeed in some aircraft designs. Observe the manufacturer’s recommendations regarding power settings.);
  • Make nose-down pitch changes slowly, even in gusting conditions, if circumstances allow; and
  • If a pneumatic deicing system is used, operate the system several times in an attempt to clear the tailplane of ice.

Tailplane Stall Symptoms

  • Once a tailplane stall is encountered, the stall condition tends to worsen with increased airspeed and possibly may worsen with increased power settings at the same flap setting.
  • Airspeed, at any flap setting, in excess of the airplane manufacturer’s recommendations, accompanied by uncleared ice contaminating the tailplane, may result in a tailplane stall and uncommanded pitch down from which recovery may not be possible.
  • A tailplane stall may occur at speeds less than the maximum flap extended speed (VFE).

Propeller Icing

Propeller Icing

  • Ice buildup on propeller blades reduces thrust for the same aerodynamic reasons that wings tend to lose lift and increase drag when ice accumulates on them.
  • The greatest quantity of ice normally collects on the spinner and inner radius of the propeller.
  • Propeller areas on which ice may accumulate and be ingested into the engine normally are anti-iced rather than deiced to reduce the probability of ice being shed into the engine.

Instrument Icing

Instrument Icing

See in chapter: Flight Instruments

Basic flgiht instruments

You need to have a thorough understanding of the build and operating principles of the basic insturments we use. This is fundamental for learning modern avionics and detection of their failure while flying.

Pitot- static instruments

Generic system description

  • todays systems mostly use a separate pitot(total) pressure and static port

  • they might also be doubled for redundancy

  • pitot heads are heated against icing

  • on small aircrafts an alternate static

source is usally indcluded which is not

as accurate as the normal system!

Sensitive altimeter

  • aneroid barometer measuring absolute pressure
  • contains capsules which expand or contract with the change of static pressure
  • this movement drives the needle of the instrument
  • range and design can vary slightly
  • the altimeter setting scale can be in Hgin or hPa (mBar)
  • be familiar with the type your aircraft has

Errors - altimeter

  • always check on ground before take-off - set QNH and the altimeter should read the elevation

  • mechanical errors (wear, manufacturing imperfections)
  • temperature error - different temp that calibration temp (ISA)
  • low temperature correction can be necessary
  • pressure error - incorrect altimeter subscale setting

Vertical speed indicator

  • measures the rate of change of static pressure

  • one aneroid capsule with static pressure inside

  • the static pressure around the capsule is routed through a choke

  • as the pressure changes there will be a pressure differential between the case and the surroundings which causes the capsule to expand/contract

  • it has noticeable lag (3-5 sec)

Air Speed Indicator

  • senses dynamic pressure by subtracting static pressure from the total pressure

Errors - ASI

  • mechanical

  • position error - pitot tube and static port place and position relative to the flow

  • manoeuvre induced errors

Blockages

  • various things can block either sources, dust, moisture, insects

  • if the pitot tube is blocked the only affected instrument is the ASI

  • if the drain hole is open, the pressure will equalize and the ASI stops working

  • if the drain hole is blocked too the ASI will act like an altimeter

Blockages

  • if the static is blocked but pitot is clear when the aircraft deviates from the altitude where the blockage happened its going to:
  • if you climb the ASI under reads - indicates lower than actual
  • if you descend it over-reads - indicates more

  • the altimeter freezes indicating the altitude where the blockage occured

  • the VSI will show 0

Alternate static port

  • some planes are provided with this emergency option - see AFM for the exact operation and location

  • the source is usually from the cockpit which makes the presssure a little bit different, usually less

  • thus the indication is inaccurate

Attitude instrument flying

Electronic Aids to instrument flying

NDB and ADF

NDB and ADF

NDB= Non Directional Beacon

  • Is a ground based transmitter which transmits radio energy equally in all directions, hence their name.
  • Modulation signal: N0NA1A long range NDB/ N0NA2A short and medium range NDB
  • NoN" unmodulated signal or carrier wave, determining the direction of the signal
  • A1A/ A2A modulated signals is used to transmit the NDB's identification

NDB and ADF

Types of NDB, with increasing power output:

  • Locator Beacon: range=15NM (for intermediate approach guidance)
  • Airways/Route Beacons: range=25-50NM
  • Long-Range Beacons range=100-200NM

The amplified signal finally reaches the transmission aerial where it is radiated omnidirectionally

NDB and ADF

Cone of silence:

  • Above the station, at which the radiated power has fallen to 0.5 of its maximum valuee, is a conical space in which the signal strength may be too low to be used.

NDB and ADF

Frequency band: upper LF and lower MF placed to produce the ground/surface wave range required

  • ICAO: 190kHz to 1750kHz
  • Europe: 255 kHz to 405 kHz

It should be noted that many other transmitters operate within the NDB band of frequencies and can be detected by the aircraft's receiver.

Beacon must be identified before of useage!!!

NDB and ADF

ADF fixed loop antenna:

NDB and ADF

ADF=Automatic Direction Finder

  • on board equipment
  • Control Panel and Indicator is represented in the cockpit
  • Circuit breaker CB for the ADF

NDB and ADF

Control Panel:

  • There are different types of ADF control panels, but their operational use is almost the same
  • Standard functions: OFF, ADF, ANT, BFO

NDB and ADF

  • Centre switch is for changing frequency
  • Two right hands buttons operate an additional ETA/stopwatch function
  • The control knobs on the right are for frequency selection and the one to the left of those is the OFF/volume control

NDB and ADF

  • "ADF"-button is the normal position when the pilot wants bearing information to be displayed automatically by the needle
  • "ANT" is the abbreviation of antenna and, in this position, only the signal from the sense aerial is used. This result in no satisfactory directional information to the ADF needle. The reason for selecting ANT position is that gives the best audio reception. This allows for easier identification of the NDB station.

NDB and ADF

  • The "BFO" stands for Beat Frequency Oscillator. (labelled TONE) Necessary to select the BFO "ON" position when identifying NDBs that use A1A transmissions. BFO circuit imposes a tone onto the carrier wave signal to make it audible to the pilot, so that the NDB signal can be identified

NDB and ADF

In some types of receivers the ADF needle will go to a "park" position (090 deg relative) when no signals are received

NDB and ADF

Identification:

  • Each NDB is identifiable by two or three lettered Morse code identification signal, which is transmitted together with its normal signal
  • This is known as its IDENT. When tuning an NDB it is absolutely essential that hte facility is correctly identified before being used for navigation

NDB and ADF

Bearing indicators:

  • Fixed card indicator or Relative Bearing Indicator (RBI)
  • Manually rotatable card (in Tréner Kft. Aircrafts)
  • Radio Magnetic Indicator (RMI) (In Tréner Kft. FNTP II. Simulator)

NDB and ADF

RBI/Fixed Card Indicator:

  • Bearing displayed on a fixed card indicator is a relative bearing
  • Since the card is fixed, 000 is always at the top and 180 deg. is always at the bottom
  • Relative Bearing is always measured clockwise
  • QDM/QDR is not directly indicated under the pointer

NDB and ADF

Manually rotatable card:

  • Card can be rotated to reflect the aircraft's heading
  • When the card is aligned with the Directional Gyro, the head of the needle will indicate QDM and the tail QDR.
  • This eliminates any need for mental arithmetic but does require constant manual realignment.

NDB and ADF

Radio Magnetic Indicator (RMI):

  • The compass card is aligned automatically with Magnetic North
  • Normally has two needles formed as arrows
  • The needles may be selectable to indicate ADF or VOR nav 1/nav 2 information

VOR

VOR

  • VOR= VHF Omnidirectional Range
  • which implies that it operates in the VHF band
  • range approximately: 200NM
  • The signal transmitted by the VOR contains directional information. As opposed to the NDB, which transmits a non-diretional signal.

VOR

  • The principle of operation is bearing measurement by phase comparison.
  • This means that the transmitter on the ground transmits signals which make it possible for the receiver to determine its position in relation to the ground station by comparing the phases of two signals.

VOR

  • In theory, the VOR produces a number of tracks all originating at the transmitter.
  • These tracks are called "radials" and are numbered from 1 to 360
  • Radial 360 is the track leaving the VOR station towards the magnetic North
  • And if you continue with the cardinal points, radial 090 points to the East, the radial 180 to the South and the radial 270 to the West, all in relation to the magnetic North

VOR

Ground Installation:

  • The VOR system operates on frequencies between 108 and 118 MHz
  • Channel separation is 50 kHz and the signals have a horizontal polarization
  • Frequencies between 108 and 112 MHz are used for the localizer part of the ILS and Terminal VORs (short range VORs)

VOR

  • Localizer: uses odd decimal as the first digit after the last MHz digit
  • T-VOR: uses even decimal as the first digit after the last MHz digit
  • For example:

108.0 to 111.95

108.10 Localizer

108.15 Localizer

108.20 T-VOR

108.25 T VOR

108.30 Localizer

108.35 Localizer

VOR

  • Between 112.0 and 117.95 MHz are solely used by VOR, both on odd and even frequencies
  • The frequency of VOR's near aerodromes are often used to transmit the ATIS (Automatic Terminal Information Service)

VOR

Airborne Equipment:

  • Aerial
  • Receiver
  • Indicator

VOR

Aerial and receiver:

  • Small horizontal dipole
  • Must be mounted in such a place that it offers 360 deg. reception of the radio signals. Aerials are frequently mounted on the fin.
  • Receiver compares the reference signal and the variable signal in order to detect the phase difference between the two.

VOR

Identification:

  • Thereceiver panel has a frequency selector knob, a dial indicating the selected frequency and a selector swich with a volume control for IDENT and Voice
  • IDENT position is selected when we want to hear the identification signal of the VOR
  • On most NAV receivers this involves pulling out the volume control knob or pushing a button on the audio selector panel

VOR

Identification:

  • It is very important to check the ident before using the navaid, otherwise you cannot relay on the displayed navigational information
  • The ident is transmitted according to ICAO recommendations and consists of a three lettre Morse code
  • Signal shall be repeted three times every 30 seconds

VOR

Course Deviation Indicator (CDI):

  • OBS: Omni Bearing Selector
  • TO/FROM Flag
  • Course Deviation Indicator
  • (Warning flag): is also a part of the indicator, most commonly an "OFF" flag. This usually appears in place of the TO/FROM flag.

VOR

OBS:

  • Is used to select the desired course (radial inbound or outbound) in relation to the VOR station
  • Select the desired course above the course index

VOR

TO/FROM indicator:

  • Tells you if the selected course will take you to or away from the VOR station
  • The TO/FROMindicator divides the area around the VOR in two main halves, a TO SECTOR and a FROM sector
  • A "Changeover line" separates the two

VOR

The FROM indicatior:

  • Will appear when, considering the current radial on which the aircraft lies, the selected bearing is extending "FROM" the beacon

The TO indication:

  • When the selected bearing reciprocal is extending "TOWARDS" the beacon

  • The indication will change from "TO" to "FROM" when a radial, perpendicular to the selected bearing, is crossed.
  • https://pyrochta.ch/de/index.php/r-nav/vor

VOR

CDI:

  • The CDI indicates your position relative to the selected course and it will move to the left or right according to relative position to the course selected
  • The needle moves across a scale of dots, each representing a certain number of degrees of deviation
  • There are indicators with 5 dot scale (to each side) or, less commonly, some with two dots on each side

VOR

CDI:

  • Deflection to the last dot represents 10 deg. displacement from the course selected. (full scale deflection)
  • On a five dot scale each dot represents 2 deg. of deviation while, on the 2-dot scale, each dot represents 5 deg.

VOR

Warning Flag:

  • The warning flag appears when no signal is received, or when the signal received is too weak
  • Most common is a flag with the text "OFF" or "NAV"
  • The "OFF" or "NAV" flag will most likely momentarily appear as we cross within the cone of confusion.

VOR

Cone of confusion:

  • This cone is the area above the beacon where the signal is unreliable
  • According to ICAO recommendation, a VOR should transmit signals up to an elevation of 40 deg., but more likely practical radiation will be up to 80 deg, in elevation

VOR

  • The indication on the CDI are totally independent of aircradft heading
  • it displays the aircraft position in relation to the course selected
  • When the OBS is turned to centre the CDI needle, with the FROM flag showing, the number indicated on the top of the compass scaleis the radial on which the aircraft is situated
  • "TO" indication and CDI centered, radial= "lower course index"
  • "FROM" indication and CDI centered, radial= "upper course index"
  • https://pyrochta.ch/de/index.php/r-nav/vor

VOR

Opposite sense:

  • In order to have the indications of the CDI indicating the correct direction to turn in order to regain the selected track, there has to be a general agreement between aircraft heading and track selected
  • If flying towards the VOR with a FROM indication, the CDI needle will indicate in the opposite sense to the actual situation
  • https://pyrochta.ch/de/index.php/r-nav/vor

VOR

  • HSI (Horizontal Situation Indicator)

DME

DME

  • Distance Measuring Equipment
  • DME provides navigational assistance in the form of range from a ground station
  • Whils useful for en-route navigation it is particularly advantageous at terminal areas during the climb and descend procedures

DME

  • DME is a secondary radar sytem
  • a short pulse pair is transmitted from an aircraft (interrogator) to a responder beacon at a ground station (transponder)
  • After a 50 microsecond delay, called station delay, the ground station replies with a similar pulse pair, on a different frequency
  • The time taken for the round trip, less the station delay, is a measure of the distance from the aircraft to the ground station and back
  • Half of this distance is the slant range of the aircraft from the station

DME

Frequencies:

  • DME operates in the UHF band between frewuencies 960 and 1215MHz at one MHz intervals
  • DME was designed to be co-located with a VOR. (Paired)
  • By selecting a VOR frequency, the pilot automatically selects the associated DME frequency

DME

DME Ground Speed Read Outs:

  • The accuracy of the reading depends on the relative velocity and altitude of the aircraft to the ground station
  • If the aircraft is at high altitude near the station, the distance will relate more to the height of the aircraft
  • Is only accurate if the aircraft is heading directly towards or away from thebeacon and not close to it
  • For example, if the aircraft is flying a DME arc procedure it will be moving at a tangent to a circle from the beacon and the ground speed reading will be approximately zero

Using the navigation instruments

How to set up the instruments and understaning their indication; track guidance

NDB - ADF

Usage

When you are instructed to fly a certain track relative to an NDB station this is what you need to do

1. get frequency from a chart and tune it

2. identify the beacon with morse code

3. decide your position to the beacon

4. calculate the difference between your position and the track

5. decide which interception to use

6. decide the direction of first turn

7. calculate interception headings

Terminology

There are two types of tracks to fly to/from an NDB

1. QDM - is the magnetic bearing to the station - QDM 270 for example means flying to the station on a track 270(M)

Terminology

2. QDR is the magnetic bearing from the station - QDR 090 means flying away from the station on a track 090(M)

Interceptions

Homing: simply means fly direct over the station. ATC requires you to turn and fly a constant magnetic track towards the station (apply wind correction)

90/45 degree interception: if the difference between the postition and the track is more than 30 degrees

45 degree interception: if the difference is 30 degrees or less

90/45 interception

Since the distance is big you need to get close to the track.

Fly 90 degrees to the QDM and when you are 20 degrees before turn to intercept the QDM/QDR at a 45 degrees angle.

45 interception

This is a simple interception. You only need to decide which way do you need to start the turn and take a 45 degree interception track to the QDM/QDR

First turn

After deciding on the interception you need to decide which way to turn. Always turn in a direction that results in the higher ditance to the beacon upon interception. Here are some examples

VOR

Usage

For the intitial usage the same principle applies as for NDBs. However the way of obtaining position is different. After tuning and identifying the VOR turn the OBS until CDI cetralises

You can read the radial you are on at the top yellow arrow with the FR (from) indication on the instrument. If the the VOR reads TO then your position is the one at the bottom yellow arrow. Pay attention which one is showing on the instrument or turn the OBS until you get from indication.

GS indicator

CDI

Usage

Usual instrcutions indclude the radial you need and wether you need to fly IN or OUT on it.

ex.: HA-TUR FLY INBOUND ON RADIAL 270

In this case you need to fly 090 heading while homing to the station. On the instrument radial 090 needs to be set to get the TO indication.

After crossing the VOR set 120 radial and turn heading 120 to have the FROM indication and the CDI in the centre while flying away from the VOR.

45 interception

This is the same interception with the same calculations as the NDB. But since the deviation scale only shows 10 degrees on either side of the centre the CDI will go out to the left or right limit when you select the radial.

It will only start moving when you come within 10 degrees of the selected radial. The speed depends on the distance from the VOR.

Another important difference is that the indication is indipendent of your heading, because it is taking the position from the VOR. The ADF however indicates the beacon position from the aircraft.

90/45 interception

This is the same calculation again. The only difference is first you need to select the radial 20 degrees before the required radial. This will be the point where you stop the 90 closing leg and start the 45 degrees interception.

DME

DME usage

DME beacons are usually colocated with VORs or ILS glideslope antennas.

In these cases they can be tuned on the same frequency and they have the same morse idents. You don't need to tune the DME separately because the VOR frequencies and the DME channels are paired and by tuning the VOR the DME will be tuned as well so you only need to ident once.

In some aircrafts (HA-TUP) the on board equipment might not be connected to the NAV sets. In this case you tune and idnet the VOR and the DME separately.

DME usage

If you suspect the DME is unservicable but you have the VOR course you can check it easily. Every 6th ident is transmitted by the DME which is higher in pitch. If that is missing the DME is u/s.

Bendix-King DME

This DME is found in Tréner's IR aircrafts.

The N1 and N2 chooses which navigation set (if there is 2) is coupled with it. DME for the navaid tuned on the appropriate set will be displayed. It also calculates speed and time to the station. Both are ony valid when proceeding directly to the beacon.

The HLD (hold) permits the pilot to tune another VOR or ILS without losing distance from the previous one. The instruments hold the DME channel from the navigation set from which the knob vas turned into the hold mode. This is displayed in the upper inde next to the distance with the appropriate number and an H -> 1H or 2H

DME arc

A commonly used tool in procedure design where a curved path is necessary. It appears on charts as an arc of constant distance. In practice it's made up of short straight sections.

Flying the DME arc

Joining the arc might be a prescribed track or it might be left up to the pilot. You should know at what distance you need to turnto capture the arc.

Position information is taken from the VOR. First you turn in the direction of the arc 90 degrees relative to your radial. Turn the OBS until the CDI is at half deflection (5 degrees) "before" you and showing FR. Now look at the top read the radial and subtract 90 for a left arc and add 90 for a right arc. That is the heading you need to steer. When the CDI is 5 degrees behind you, repeat the above.

Holdings

Holdings

Holdings are used when an aircraft needs to "stop" or wait for some reason.

ATC can instruct you to hold because of high traffic, to give priority to aircraft in emergency, clearance limits and missed approaches often contain a published holding nearby the airport.

The pilot can also ask for holding for various reasons. If they need time to asses a fault or emergency situation, prepare for a special approach and landing, do a normal approach briefing, or just wait for the weather to get better.

Holdings

Holdings are also called racetrack patterns because of their shape. It is defined by a fix and an inbound track. Crossing the fix a standard 180 turn (1 min) is initiated and then a 1 minute long straight follows with hte reciprocal heading of the inbound. Timing is started when abeam the beacon After 1 min another 180 turn establishes you on the inbound. This way when you cross the fix again altogether 4 minutes have passed. However above 14,000 feet the straigth parts are 1 min 30 sec long.

Entries

Holdings are designed to be low-workload procedures. Probably the most complicated part is joining the holding.

The way to join the pattern is decided based on your track towards the fix.

1. is called parallel

2. is called teardrop or offset

3. is called direct entry

This is never told by ATC you are required to fly the appropriate type.

Buffers

These procedures are always designed taking into account the pilots capabilities. Every holding has a certain safety area around it which is safe for manoeuvring. It aslo has a so called minimum holding altitude. This provides clearance from obstacles. Remember: never turn onto the non holding side and never go below MHA.

Direct

  • upon crossing the station you can turn directly onto the outbound leg
  • the outbound is only track, no guidance from any beacon
  • it has a special case when you enter with a track approx 90 degrees to the inbound. in this case you time 15 second after crossing and then turn onto the outbound

Teardrop

  • after crossing the fix turn INTO the holding
  • procced 1 min on a track 30 degrees different than the inbound's reciprocal
  • then turn to intercept the inbound track

Paralell or offset

  • after crossing the station turn to the reciprocal heading of the inbound
  • after 1 minute turn INTO the holding until you are on a 45 degree interception heading to the inbound track

Flexibility

On the border of teardrop and parallel entries there is a zone in which you can opt for either enty. This is the zone of flexibility and it is +-5 degree on both sides of the sector 1 and 2 entries

Non-standard holding

The standard holding is always with turns right. Non-standard holding are with left turns. The entires are also changed. Pay attention to the direction because you easily end up on the non-holding side.

Calculations

Here is a fast way to determine the holding entry.

  • the airplane is heading over the fix on HDG 300
  • standard holding inbound 270

  • holding entry is a direct

  • it is clearly visible from this drawing but it isn't that easy in the aircraft

Easy- way using the DGI

  • in case of a standard holding draw this pattern on the DGI in your mind

  • find the inbound track on the dial

  • check which sector it is

  • it is easy as you often need to look at the DGI
  • only works when heading direct to the fix

Easy way - non standard holding

  • the pattern is mirrored fo non standard holdings

  • tha a/c fliles on heading 300
  • the holding is Non-standard with inbound 090

  • locate EAST on the DGI
  • you can see it is a teardrop entry

Radio Communaication facilities and equipment

Airways system and controlled airspace

Operational Procedures and Air Law

Flight Planning and monitoring

Performance Based Navigation

Satellite systems

Future naviagtion systems and equipments

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