Instruments And Ilusions Flashcards
Gyroscopic instruments
two principles. There has to be a source of power to keep the gyro spinning. With vacuum system the attitude and heading indicator is driven by the vacuum system. The turn coordinator is electrically driven for redundancy. The gyro spins on a horizontal plane. Dual gimbal, gimbal rotation, roll gimbal, pitch gimbal gyro, horizontal reference arm, and bank index
Gyroscopic principle 1: Rigidity in Space
a wheel with a heavily weighted rim tends to remain in the plane in which it is spinning unless acted on by an outside force. No matter where you move the base of the gyro it will remain in the plane
Gyroscopic principle 2: Procession
any force applied to a gyro or a spinning object will be felt 90 degrees ahead in the plane of rotation
Principles and instruments
Attitude indicator- rigidity and space
Heading indicator- rigidity and space
Turn coordinator- procession
Vacuum pump
Relies on vacuum pressure through a vacuum pump to create suction to spin gyroscopes. Pulls through an air filter to the instruments and then to a relief valve then to an overboard vent.
Vacuum pump errors
Indication of low vacuum, suction gauge reading low, 4.8-5.2in hg is normal.
If it completely fails the attitude indicator will fall off.
Heading indicator will freeze and won’t move. Auxiliary driven pump is back up.
Shear drive on the vacuum pump breaks off if the vacuum goes to fats, this is a plastic piece on the vacuum pump
Attitude Indicator
Consist of miniature aircraft
Principle of operation- shows direct indication of pitch and bank. Operates in the principle of rigidity and space.
The gyro spins on a horizontal plane mounted on dual gimbal
Pendulous vane- located at the bottom of the gyro corrects for unwanted procession. It deflects the other way for correction. Depends if the inlets are open or closed. Open due to gravity when the gyro strays away from horizontal
Rigidity and space
Attitude indicator Errors
The forces placed on the gyro
Acceleration/deceleration- Acceleration slight pitch up, deceleration slight pitch down
Instrument tumbling- 60 degrees of pitch or 100 degrees of bank. The instrument will tumble and won’t become reliable. It will keep spinning. Caging stops the gyro from spinning and spinning
Maximum when rolling out of a 180 degree turn- Show a false pitch and bank in the opposite direction. 360 degrees it will cancel.
Attitude indicator preflight check
Attitude Indicator up and erect within 5 minutes
No more then 5 degrees bank or one bar of pitch on taxi turns
Miniature aircraft set to horizon
Heading Indicator
Provides heading information (magnetic compass) Magnetic North
Heading Indicator Principles of operation
Primary source for heading information
Operates on the principle of rigidity in space
Senses aircraft movement about the vertical axis (yaw)
Slaved vs Free gyros. Slave automatically aligns to the magnetic compass. Free gyros manually has to be set to the magnetic compass
Gyro mounted in the vertical plane so it spins vertical plane
Dual gimbals are required because the a/c rolls and yaws
Keeps the gyro fixed in the vertical plane
Doesn’t have a mechanism to correct for precession
Heading Indicator Errors
Procession causes the heading indicator to drift from its set heading. It’s kind of like friction is always messing with it.
Reset with Magnetic compass every 15 minutes. Due to the earth’s rotation
Only in straight and level unaccelerated flight it will be most accurate
Heading Indicator Preflight Check
Heading aligned with magnetic compass
Doesn’t process more than 3 degrees in 15 minutes
Turn Indicator
Both show quality of turn Inclinometer. Works on the principle of procession
Turn and Slip indicator:
Rate of turn information only
Mounted vertically
Turn coordinator:
Rate of turn and rate of roll information
Mounted canted (30 degrees)
Turn Indicator Principle of Operation
Operates on the principle of precession
Allows the pilot to establish and maintain standard rate turn 3 degrees per second/ 2 minutes 360, 1 minute 180, 30 seconds 90 degrees, 15 sec 45 degrees, 10 second 30 degrees.
Equation (TAS/10) + 5 = Angle of Bank
Slip- ball on the inside of the turn. Not enough rate of turn for the amount of Bank
Skid-ball on the outside of the turn. Too much rate of turn for the amount of bank
Turn indicator Preflight check
Inclinometer full of fluid and centered
Wings level while stationary
Skidding turn on the ground
Wings into the turn, ball on the outside
Magnetic Compass
is the most primal and basic instruments used by the pilot to determine or verify aircraft heading. The instrument operations on the principles of magnetism. Can’t freeze because the fluid is kerosene.
Magnetic Compass Errors: Deviation
Due to interference to magnetism in the aircraft. Need a Magnetic deviation card in A/C
Magnetic compass error: Variation
also known as declination errors, stem from the disparity between magnetic north and true north. This difference varies depending on geographical location and must be accounted for during navigation
Magnetic compass errors: Magnetic dip theory
Dip errors are caused by the tilt of the compass needle caused by the Earth’s magnetic field. As one moves closer to the magnetic poles, the compass needle’s dip angle increases, leading to inaccuracies.
Magnetic compass errors Oscillation
Oscillation errors refer to the unwanted swinging or movement of the compass needle, often caused by rough sea conditions or turbulent flight paths.
Magnetic compass error North/South Turning Errors
North lags and south leads. UNOS, undershoot north overshoot south
Magnetic compass error Acceleration/Deceleration
Shows Acceleration to the north, shows decelerate south only on a East or West heading
Airspeed indicator
used in an aircraft to display the craft’s airspeed, typically in knots. Airspeed indication is accomplished with the use of a thin, corrugated phosphor bronze diaphragm (aneroid) which measures the Dynamic Pressure of the air between the Pitot tube (ram air) and static port (static pressure)
Airspeed indicator Preflight
0 Taxi unless strong head wind
Call alive on takeoff
Types of Airspeed: Indicated
Airspeed directly off the airspeed indicator
Types of Airspeed: Calibrated
corrected for position and instrument error. Errors such as AOA, flap configuration, ground proximity, wind direction.
Types of Airspeed: Equivalent
corrected for calibrated airspeed at airspeed above 200 knots and altitudes above 20,000
Types of Airspeed: True airspeed
speed of the a/c relative to the calibrate airspeed corrected.TAS is therefore CAS corrected for non-standard temperature, with the help of an Outside Air Temperature (OAT) gauge, and altitude
Types of Airspeed: Ground speed
is the actual speed of the airplane over the ground
Altimeter
is a type of barometer which measures the vertical distance to the surface, necessary for a pilot to maintain the desired or assigned altitude during flight. Stack of sealed aneroid wafers (29.92)
Static source to the case of the instrument
Altimeter preflight Check
Plus or minus 75 feet
Set to current altimeter setting
Types of Altitude: Absolute Altitude
AGL height above ground level
Types of Altitude: Pressure Altitude
Height above the standard datum of the plane. This is the altimeter reading that corresponds to the altitude in the standard atmosphere where the pressure is the same as you are
Types of Altitude: Density Altitude
Pressure altitude corrected for non-standard temperature. This is most important to takeoff and climb performance of an aircraft
Types of Altitude: Indicated Altitude
altitude read directly off the altimeter
Types of Altitude: True Altitude
MSL height above mean sea level. Actual aircraft’s height above sea level
Altimeter Errors: Pressure errors
High to low look out below (true altitude is lower than the indicated altitude. Low to high clear the sky (true altitude is higher than indicated.
If its Warmer your flying higher than what you actually are
If its colder your flying lower than what you actually are
Vertical speed indicator
is an instrument that displays rate of climb and descent to the pilot by measuring rate-of-pressure changes
Soley operated off of static pressure.
Contains a diaphragm is connected to the static pressure
As aircraft climbs the static pressure in the diaphragm lowers. As aircraft descends the static pressure in the diaphragm increases. Displays trend and rate. Trend immediate indication, rate is gradual
Vertical speed indicator Preflight check
The VSI should read 0
If it indicates anything other than a zero feet per minute climb or descent on the ground, then the instrument can still be used, but that indication is the new “zero”
Pitot static Blockages: Pitot tube block drain hole open
Airspeed 0
Pitot static Blockages: Pitot tube and drain hole block
Airspeed indicator acts as an altimeter. When you ascend its going to read lower. When you descend its going to read higher
Pitot static Blockages: Static port block
Airspeed only reads accurate at the aircraft the static port blocked. Altimeter will freeze when blocked. VSI will gradually go to 0.
Alternate static
pulls air from the cockpit. Airspeed reads higher, Altimeter reads higher, VSI indicates a climb but gradually comes back down to 0
PFD
PFD(primary flight display)- 6 pack instruments
MFD
Multifunctional display
Standby
Aspen and G5
ADC (Air data computer)
Uses the pitot tube, static source, OAT probe. ASI, ALT, VSI, OAT, TAS. Read X over it if there is an error
AHRS (Attitude Heading Reference System)
Use solid state gyros, accelerometers, magnetometers (determines earth magnetic field one in each wing)
Cross-check
Scanning instruments. A logical systematic observation of the instruments.
Cross-check errors: Fixation
solely looking at 1 instrument excluding all others.
Cross-check errors: Emphasis
Giving an instrument more attention than the others
Different types of cross-checking: Selected radial cross-check
80-90% of scan is focused on the attitude indicator
The scan begins with attitude and branches out to various other instruments, but the scan always return to attitude before checking the next instrument branches will depend on maneuver
Different types of cross-checking: Rectangular cross-check
Scan moves in a clockwise or counter-clockwise direction around the basic six-pack, thus creating a rectangular pattern
Gives equal weight to each instrument
Can lengthen the time between checking instruments critical for maneuver being performed
Different types of cross-checking: Common cross-check
Common cross-check for a beginner is rapidly looking at different instruments without knowing why or what they are looking for
With experience the common cross-check becomes a habit, you look at the instruments needed for the given situation, you know what to look for and how long to look
Instrument Interpretation
Understand the different errors of the instrument. Understanding what the instruments are telling you
Aircraft control
Properly control the airplane to where it can move the most effectively
Attitude instrument flying: Primary and supporting
Divides instruments panel into pitch, bank, and power instruments. Primary instruments provide the most essential information
Primary/Supporting: Straight and level
Power: Primary= Airspeed/ Secondary= Tachometer and Manifold Pressure
Bank: Primary= Heading/ Secondary= Attitude Indicator, Turn Coordinator, and Magnetic compass
Pitch: Primary= Altimeter/ Secondary= Airspeed, Attitude indicator, and VSI
Primary/Supporting: Starting Climb/Descent
Power: Primary= Tachometer/ Secondary= Airspeed and Manifold Pressure
Bank: Primary= Heading/ Secondary= Attitude Indicator, Turn coordinator, and Magnetic Compass
Pitch: Primary= Attitude/ Secondary= Airspeed, Altimeter, and VSI
Primary/Supporting: Climb/Descent Constant Airspeed
Power: Primary= Tachometer/ Secondary= Airspeed and Manifold pressure
Bank: Primary= Heading/ Secondary= Attitude Indicator, TC, and Magnetic Compass
Pitch: Primary=Airspeed/ Secondary= Attitude Indicator, Altimeter, and VSI
Primary/Supporting: Climb/Descent Constant Rate
Power: Primary= Tachometer/ Secondary= Airspeed and Manifold Pressure
Bank: Primary= Heading/ Secondary= Attitude Indicator, TC, and Magnetic Compass
Pitch: Primary= VSI/ Secondary= Airspeed, Attitude Indicator, and Altimeter
Primary/Supporting: Starting a Turn
Power: Primary= Airspeed/ Secondary= Tachometer and Manifold Pressure
Bank: Primary= Attitude/ Secondary= Heading, TC, and magnetic compass
Pitch: Primary= Altimeter/ Secondary= Airspeed, Attitude Indicator, and VSI
Primary/Supporting: Established in Turn
Power: Primary= Airspeed/Secondary=Tachometer and Manifold Pressure
Bank: Primary= Turn coordinator/ Secondary= Heading, Attitude Indicator, and Magnetic Compass
Pitch: Primary= Altimeter/ Secondary= Airspeed, Attitude Indicator, and VSI
Control and Performance
Divide the instrument in 3 groups.
Control and Performance: Control
(Independent variable) Tachometer and Attitude Indicator
Control and Performance: Performance
how the plane responds to those conditions and changes. (Dependent variable) depends on the tachometer and attitude indicator. Airspeed indicator, Altimeter, Turn coordinator, Vertical speed indicator, Heading
Control and Performance: Navigation
position of the A/C compared to a fix. VOR, GPS, Localizer, Glides slope
How to use control and performance
establish an attitude and power setting on the control instruments that result in the desired performance. Prior knowledge of the aircraft
Trim- until control pressure is neutralized
Cross check- the performance instruments to determine if the established attitude or power setting is providing the desired performance. If a deviation is noted make the proper adjustments.
Adjust
Inversion
when you are climbing then you rapidly go to straight and level you can feel like you are tumbling backwards
Coriolis
In a stablized turn and the fluid in your ear is stablized. If you move your head and the fluid in your ear becomes unstable and it can make you feel like you turning
Elevator
caused by turbulence updraft, downdraft. Makes you feel like your climbing
False horizon
Think the horizon is one place but its in a whole other place. Use instruments as reference
Leans
get into an unnoticed turn and you ear noticed your turning and it makes you feel like your turning the other way when your really straight and level
Autokinesis
Caused by staring at a single point of light against a dark background for more than a few seconds
After a few moments, the light appears to move on its own
The disoriented pilot will lose control of the aircraft in attempting to align it with the light
Graveyard Spin/ Spiral
Spin: An abrupt stop can stimulate a spin in the opposite direction
Spiral: An observed loss of altitude during a coordinated constant-rate turn that has ceased stimulating the motion sensing system can create the illusion of being in a descent with the wings level
Somatogravic
A rapid acceleration, like experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backward
This action creates the illusion of having a nose-up attitude, especially in situations without good visual references
The disoriented pilot may push the aircraft into a nose-low or dive attitude
Spatial disorientation
receiving conflicting messages from these 3 areas. the eyes, somatosensory skin muscles and joints and, vestibular system (inner ear, semicircular canal)
