aircraft instruments (1)
TRANSCRIPT
Aircraft InstrumentsAircraft Instruments
Pitot – Static SystemPitot – Static System
Airspeed Indicator Airspeed Indicator SymbologySymbology
►White Arc – Flap White Arc – Flap operating Rangeoperating Range
►Green Arc – Normal Green Arc – Normal OperationsOperations
► Yellow Arc – Yellow Arc – Caution Area (Only Caution Area (Only use in smooth air)use in smooth air)
►Red Line – Never Red Line – Never Exceed SpeedExceed Speed
Aircraft AirspeedsAircraft Airspeeds► Vso – Stall speed in landing configurationVso – Stall speed in landing configuration► Vs – Stall speed in clean (flaps up) configurationVs – Stall speed in clean (flaps up) configuration► Vy – Climb speed for the max amount of height v. timeVy – Climb speed for the max amount of height v. time► Vx- Climb speed for the max amount of height for Vx- Climb speed for the max amount of height for
distancedistance► Vfe- Flap Extension speed: Flaps should not be used Vfe- Flap Extension speed: Flaps should not be used
above this speedabove this speed► Va – Design maneuvering/rough air speed: Speed at Va – Design maneuvering/rough air speed: Speed at
which abrupt full control inputs can be used without which abrupt full control inputs can be used without risking structural damage. Should never be exceeded risking structural damage. Should never be exceeded in rough air. Changes with weightin rough air. Changes with weight
► Vno – Max structural Cruise speedVno – Max structural Cruise speed► Vne – Never Exceed SpeedVne – Never Exceed Speed
Types of AirspeedsTypes of Airspeeds► Calibrated
Speed corrected for installation and instrument errors. At high angle of attack, the pitot tube does not point straight into the
relative wind, this tends to make the airspeed indicate lower than normal at low airspeeds.
Not usually a problem in cruise, usually we only worry about calibrate airspeed when we are converting to true airspeed.
► True The actual speed of your airplane is moving through undisturbed air. On a standard day, Calibrated airspeed will be equal to TAS. As density altitude increases, true airspeed increases for a given CAS or
amount of power. TAS can be calculated by using CAS with temperature and pressure on your
E6B
► Equivalent Calibrated airspeed corrected for adiabatic compressible flow at a
particular altitude. Above 200 kts and 20,000 feet air compresses in front the pitot tube
causing abnormally high airspeeds. Many flight computers are designed to compensate.
Airspeed IndicatorAirspeed Indicator► Uses ram air from the pitot tube as well as static air.Uses ram air from the pitot tube as well as static air.► Ram air pushes against a diaphragm inside the Ram air pushes against a diaphragm inside the
airspeed indicator, which will then be able to expand airspeed indicator, which will then be able to expand or contract accordingly. This movement of the or contract accordingly. This movement of the diaphragm is then translated into needle movement.diaphragm is then translated into needle movement.
Airspeed IndicatorAirspeed Indicator
► If the Pitot tube is blocked and the drain is open, speed will go to zero.If the Pitot tube is blocked and the drain is open, speed will go to zero.► If the Pitot tube is blocked and the drain is open, it will act as an If the Pitot tube is blocked and the drain is open, it will act as an
altimeter.altimeter.► If the the Static vent is blocked, the airspeed will read higher than it If the the Static vent is blocked, the airspeed will read higher than it
should above altitude where it became blocked and lower than it should above altitude where it became blocked and lower than it should below.should below.
► If all three all blocked, the needle will freeze.If all three all blocked, the needle will freeze.
Questions?Questions?►How does the airspeed indicator How does the airspeed indicator
compute indicated airspeed?compute indicated airspeed?►How will we know if we have a blocked How will we know if we have a blocked
pitot tube?pitot tube? What would you do?What would you do?
►Will you need to compute your Will you need to compute your equivalent airspeed for flight?equivalent airspeed for flight?
AltimeterAltimeter► Static Input OnlyStatic Input Only►Manufacturer seals Manufacturer seals
the aneroid wafer(s) the aneroid wafer(s) at a specific pressure. at a specific pressure. As the static pressure As the static pressure fills in the area fills in the area around these sealed around these sealed wafers, they will be wafers, they will be able to contract or able to contract or expand accordinglyexpand accordingly
Altimeter OperationAltimeter OperationAir moves out
Air moves in
Wafers expand
0 1 2 3
4 5
9 8 7
6
Wafers contract
0 1 2 3
4 5
9 8 7
6
0 1 2 3
4 5
9 8 7
6
Air moves out
Air moves in
Wafers expand
0 1 2 3
4 5
9 8 7
6
Wafers contract
0 1 2 3
4 5
9 8 7
6
0 1 2 3
4 5
9 8 7
6
Types of AltitudeTypes of Altitude► IndicatedIndicated
What you read on the altimeter when it is correctly adjusted to What you read on the altimeter when it is correctly adjusted to show approximate height above mean sea levelshow approximate height above mean sea level
► CalibratedCalibrated Indicated altitude corrected to compensate for instrument errorIndicated altitude corrected to compensate for instrument error
► Pressure Pressure Displayed when altimeter is set to standard sea level (29.92). Displayed when altimeter is set to standard sea level (29.92). Vertical distance above the standard datum planeVertical distance above the standard datum plane
► DensityDensity Pressure altitude corrected for non – standard temperaturePressure altitude corrected for non – standard temperature Used to determine aircraft performance, when high (temp Used to determine aircraft performance, when high (temp
above standard), performance will be worse.above standard), performance will be worse.► True True
Actual height above mean sea levelActual height above mean sea level Sectional chartsSectional charts
► AbsoluteAbsolute Actual height of aircraft above the earths surface.Actual height of aircraft above the earths surface.
Altimeter ErrorsAltimeter Errors►Make sure you update your altimeter setting as Make sure you update your altimeter setting as
often as possible (or at least every 100 miles)often as possible (or at least every 100 miles)► If you fly to an area with a lower altimeter setting, If you fly to an area with a lower altimeter setting,
without resetting your altimeter, you may fly at a without resetting your altimeter, you may fly at a lower altitude than you had intended.lower altitude than you had intended.
► ““High to low, look out below”High to low, look out below”►On warm days, true altitude is higher than On warm days, true altitude is higher than
indicated. Aircraft true altitude is lower than indicated. Aircraft true altitude is lower than indicated in colder air.indicated in colder air.
► Static BlockageStatic Blockage Altimeter will freeze at the altitude the blockage Altimeter will freeze at the altitude the blockage
occuredoccured
High to Low, Look out Below!High to Low, Look out Below!
Questions?Questions?►How does the altimeter work?How does the altimeter work?►What altitude is displayed on a sectional chart?What altitude is displayed on a sectional chart?► If I fly from an area of a pressure setting of If I fly from an area of a pressure setting of
29.92 to an area where it was 30.00, would I 29.92 to an area where it was 30.00, would I be likely to be flying above or below where I be likely to be flying above or below where I should?should?
►How would you know if the static port was How would you know if the static port was blocked?blocked? If you then turned on alternate air, what kind of If you then turned on alternate air, what kind of
indication would you generally expect?indication would you generally expect?
Vertical Speed IndicatorVertical Speed Indicator
► Rate of climb and descentRate of climb and descent► Trend will show immediate indication of an Trend will show immediate indication of an
increase in the airplanes rate of climb or increase in the airplanes rate of climb or descentdescent
► Rate shows a stabilized change in altitudeRate shows a stabilized change in altitude
Vertical Speed IndicatorVertical Speed Indicator► Static air enters both the Static air enters both the
diaphragm and the area diaphragm and the area around it. However, the around it. However, the air in the diaphragm is air in the diaphragm is constantly updated while constantly updated while the air outside of it is the air outside of it is very slowly allowed to very slowly allowed to escape through a escape through a calibrated leak. The calibrated leak. The instrument measures the instrument measures the difference in these two difference in these two pressures (the air where pressures (the air where you where v. where you you where v. where you are)are)
Vertical Speed Indicator Vertical Speed Indicator ErrorsErrors
►Blocked Static Blocked Static Zero IndicationZero Indication
►Lags: should not be relied upon to give Lags: should not be relied upon to give instantaneous informationinstantaneous information Don’t “chase the needle”Don’t “chase the needle”
Pitot – Static SummaryPitot – Static Summary►While the Altimeter, VSI and airspeed While the Altimeter, VSI and airspeed
indicator all use Static air, only the airspeed indicator all use Static air, only the airspeed indicator uses Pitotindicator uses Pitot
► If you notice all of your pitot static If you notice all of your pitot static instruments are giving conflicting instruments are giving conflicting information, try turning using the alternate information, try turning using the alternate air sourceair source
► If only your airspeed indicator is not working If only your airspeed indicator is not working properly, try turning on pitot heatproperly, try turning on pitot heat
Which instruments are Which instruments are Gyroscopic?Gyroscopic?
►Which instrument(s) are powered by the Which instrument(s) are powered by the vacuum system?vacuum system?
►Which are powered by the electrical system?Which are powered by the electrical system? Why?Why?
Gyroscopic PrinciplesGyroscopic Principles► Rigidity in SpaceRigidity in Space
A wheel with a heavily A wheel with a heavily weighted rim spun rapidly weighted rim spun rapidly tends to remain fixed in the tends to remain fixed in the plane in which it is spinningplane in which it is spinning
The wheel is mounted on a The wheel is mounted on a set of gimbals so that the set of gimbals so that the gyro is able to rotate freely gyro is able to rotate freely in any planein any plane
As the gimbals’ base tilts As the gimbals’ base tilts and twists, the gyro remains and twists, the gyro remains spinning in its original planespinning in its original plane
Allows a gyroscope to Allows a gyroscope to measure changes in the measure changes in the attitude or direction of an attitude or direction of an airplaneairplane
PrecessionPrecession► What is precession?What is precession?
When an outside force When an outside force tries to tilt a spinning gryo, tries to tilt a spinning gryo, the gyro responds as if the the gyro responds as if the force had been applied at force had been applied at a point 90 degrees in the a point 90 degrees in the direction of rotationdirection of rotation
► Precession side – Precession side – effects?effects? Friction in gimbals and Friction in gimbals and
bearings may cause a slow bearings may cause a slow drifting in the heading drifting in the heading indicator and occasional indicator and occasional small errors in the attitude small errors in the attitude indicatorindicator
Questions?Questions?►Why is the turn coordinator powered Why is the turn coordinator powered
by the electrical system?by the electrical system?►A spinning wheel tends to stay in its A spinning wheel tends to stay in its
original plane when disrupted, this original plane when disrupted, this refers to what concept?refers to what concept?
►Our heading indicator has become Our heading indicator has become inaccurate by 5 degrees since takeoff, inaccurate by 5 degrees since takeoff, what is causing this?what is causing this?
Vacuum InstrumentsVacuum Instruments
Attitude IndicatorAttitude Indicator► Only instrument that Only instrument that
gives immediate and gives immediate and direct indication of the direct indication of the airplane’s pitch and bank airplane’s pitch and bank attitude.attitude.
► OperationOperation Gyro spins in the horizontal Gyro spins in the horizontal
plane, mounted on dual plane, mounted on dual gimbals that allow it to gimbals that allow it to remain in the plane remain in the plane regardless of aircraft regardless of aircraft movement.movement.
Pendulous vanes allow the Pendulous vanes allow the attitude indicator erect attitude indicator erect itself on taxiitself on taxi
Attitude Indicator ErrorsAttitude Indicator Errors► Usually less than 5 degrees of bank error and 1 bar width of Usually less than 5 degrees of bank error and 1 bar width of
pitch error in a 180 degree turn.pitch error in a 180 degree turn.
► Pendulous vanes act on the attitude indicators gyro in an Pendulous vanes act on the attitude indicators gyro in an undesirable way during turns.undesirable way during turns.
► The same pendulous vanes will cause the gyro to try to line The same pendulous vanes will cause the gyro to try to line up with the g – forces of a turn.up with the g – forces of a turn.
► Acceleration and Deceleration can induce precession errors. Acceleration and Deceleration can induce precession errors. During acceleration, horizon bar may show a climb, During acceleration, horizon bar may show a climb, reinforcing the somatogravic illusion.reinforcing the somatogravic illusion.
► Tumbling: Past 100 degrees of bank or 60 degrees of pithTumbling: Past 100 degrees of bank or 60 degrees of pith
Heading IndicatorHeading Indicator►What does it do?What does it do?
Senses rotation Senses rotation about the aircraft’s about the aircraft’s vertical axis.vertical axis.
► Errors?Errors? Precession can Precession can
cause heading to cause heading to drift, so remember to drift, so remember to re – check about re – check about every 15 min.every 15 min.
Turn IndicatorsTurn Indicators► Turn Coordinator:Turn Coordinator:
Rate and RollRate and Roll► Slip and Skid Slip and Skid
Rate ONLY – older aircraftRate ONLY – older aircraft► What is the inclinometer?What is the inclinometer?
Slip? Rate of turn is too Slip? Rate of turn is too slow for the angle of bank, slow for the angle of bank, ball moves insideball moves inside
Skid? Rate of turn is too Skid? Rate of turn is too great for the angle of bank.great for the angle of bank.
► Standard Turn?Standard Turn?
Gyro Instruments SummaryGyro Instruments Summary►The gyroscopic instruments The gyroscopic instruments
incorporate two concepts, Rigidity in incorporate two concepts, Rigidity in Space and precessionSpace and precession
►The turn coordinator is powered by the The turn coordinator is powered by the electrical system rather than the electrical system rather than the vacuum system so that in case of a vacuum system so that in case of a failure, the pilot will always have a failure, the pilot will always have a way to reference flight attitude.way to reference flight attitude.
CompassCompass► Bar Magnet aligns Bar Magnet aligns
itself with the itself with the magnetic fieldmagnetic field
Compass ErrorsCompass Errors►Variation: Difference between the true Variation: Difference between the true
and magnetic poles. Use correction and magnetic poles. Use correction indicated on sectionalindicated on sectional
Compass ErrorsCompass Errors►Deviation: Compass error due to Deviation: Compass error due to
disturbances in magnetic field de to disturbances in magnetic field de to metals and electrical accessories in metals and electrical accessories in the airplane. Use deviation card in the airplane. Use deviation card in airplane to correct.airplane to correct.
Compass ErrorsCompass Errors►Magnetic Dip: Bar magnet contained in Magnetic Dip: Bar magnet contained in
compass is pulled by the earth’s compass is pulled by the earth’s magnetic field, it tends to point north magnetic field, it tends to point north and somewhat downward. Greatest and somewhat downward. Greatest near the polesnear the poles
Compass ErrorsCompass Errors►Acceleration Error: Occurs when Acceleration Error: Occurs when
accelerating or decelerating on an accelerating or decelerating on an easterly or westerly heading. As you easterly or westerly heading. As you accelerate, inertia causes the compass accelerate, inertia causes the compass weight on the south end of magnetic to weight on the south end of magnetic to lag and turn the compass toward north. lag and turn the compass toward north. As you decelerate, inertia causes As you decelerate, inertia causes weight to move ahead, moves the weight to move ahead, moves the compass toward a southerly heading.compass toward a southerly heading.
Compass ErrorsCompass Errors►Turning Error: Most pronounced when Turning Error: Most pronounced when
turning to or from headings of north or turning to or from headings of north or south. south.
►When you begin a turn from a heading When you begin a turn from a heading of north, the compass initially indicates of north, the compass initially indicates a turn to the opposite direction. When a turn to the opposite direction. When the turn is established, the compass the turn is established, the compass begins to turn in the correct direction, begins to turn in the correct direction, but it lags behind the actual heading.but it lags behind the actual heading.
Questions?Questions?