PHAK 8: Flight Instruments Flashcards
Pitot-Static System
Which three instruments rely on the pitot-static system?
Airspeed Indicator (ASI)
Altimeter
Vertical Speed Indicator (VSI)
Pitot-Static System
What does the pitot-static system measure?
Static air pressure and dynamic pressure due to aircraft motion.
Pitot-Static Flight Instruments: Pitot Tube
What does the pitot tube measure?
Total pressure (dynamic + static pressure).
Pitot-Static Flight Instruments: Pitot Tube
What should be checked before flight regarding the pitot tube?
Ensure the openings are not blocked by debris, bugs, or moisture.
Pitot-Static Flight Instruments: Pitot Tube
What happens if the pitot tube’s openings are blocked?
The ASI will not function properly, potentially leading to incorrect airspeed readings
Pitot-Static Flight Instruments: Static Pressure
Where is static pressure vented from?
Through small holes on the side(s) of the aircraft into the static chamber.
Pitot-Static Flight Instruments: Static Pressure
What instruments utilize static pressure?
- Altimeter
- VSI (and as part of the ASI for dynamic pressure calculation)
Pitot-Static Flight Instruments: Alternate Static Source
Why is an alternate static source used?
To provide static pressure if the primary static source is blocked.
Pitot-Static Flight Instruments: Alternate Static Source
Where is the alternate static source located?
Inside the flight deck.
Pitot-Static Flight Instruments: Alternate Static Source
What errors can occur when using the alternate static source?
- Altimeter: Indicates higher altitude than actual.
- ASI: Indicates higher airspeed than actual.
- VSI: Momentary climb, then stabilizes.
Pitot-Static Flight Instruments: Alternate Static Source
What action can be taken if no alternate static source is available, and the primary source is blocked?
Break the glass face of the VSI, as it is the least critical static instrument.
Pitot-Static Flight Instruments: Dynamic Pressure
How is dynamic pressure generated?
By the aircraft’s motion through the air or wind relative to the aircraft.
Pitot-Static Flight Instruments: Dynamic Pressure
What role does dynamic pressure play in the ASI?
It is the remaining pressure after static pressure is canceled out, indicating airspeed.
Pitot-Static Flight Instruments: Maintenance Tip
Why are pitot tube covers used?
To prevent bugs, debris, or moisture from entering when the aircraft is not in use.
Pitot-Static Flight Instruments: Altimeter
What does the altimeter measure?
The height of an aircraft above a given pressure level.
Pitot-Static Flight Instruments: Altimeter
Why is the altimeter considered vital?
It is the only instrument capable of indicating altitude.
Pitot-Static Flight Instruments: Altimeter
What is the primary component of the altimeter?
A stack of sealed aneroid wafers.
Pitot-Static Flight Instruments: Altimeter
What pressure are the aneroid wafers evacuated to?
29.92 “Hg
Pitot-Static Flight Instruments: Altimeter
What happens to the aneroid wafers when static pressure increases?
They compress, indicating a decrease in altitude.
Pitot-Static Flight Instruments: Altimeter
What happens to the aneroid wafers when static pressure decreases?
They expand, indicating an increase in altitude.
Pitot-Static Flight Instruments: Altimeter
How is the movement of the wafers translated into altitude readings?
A mechanical linkage connects the wafers to the needles on the altimeter face.
Pitot-Static Flight Instruments: Altimeter
Where is static pressure introduced in the altimeter?
Into the rear of the sealed altimeter case.
Pitot-Static Flight Instruments: Altimeter
What is the role of the sealed outer chamber of the altimeter?
It allows the static pressure to surround the aneroid wafers for accurate readings.
Pitot-Static Flight Instruments: Altimeter
What happens if static pressure equals the pressure inside the wafers?
The wafers remain stable, and there is no change in altitude reading.
Pitot-Static Flight Instruments: Altimeter
How does the altimeter respond to higher-than-standard atmospheric pressure?
The wafers compress, and the altimeter shows a lower altitude.
Pitot-Static Flight Instruments: Altimeter
How does the altimeter respond to lower-than-standard atmospheric pressure?
The wafers expand, and the altimeter shows a higher altitude.
Pitot-Static Flight Instruments: Altimeter
What type of device is a pressure altimeter?
An aneroid barometer.
Pitot-Static Flight Instruments: Altimeter
What does the pressure altimeter measure?
The atmospheric pressure at the level where the altimeter is located, presenting the measurement as altitude in feet.
Pitot-Static Flight Instruments: Altimeter
What is the relationship between atmospheric pressure and altitude?
Atmospheric pressure decreases as altitude increases.
Pitot-Static Flight Instruments: Altimeter
How are altitudes indicated on a multipointer altimeter?
- Tens of thousands of feet: Long, thin needle with an inverted triangle.
- Thousands of feet: Short, wide needle.
- Hundreds of feet: Long needle.
Pitot-Static Flight Instruments: Altimeter
What does the arrangement of numbers on the altimeter dial look like?
Numerals arranged clockwise from zero to nine.
Pitot-Static Flight Instruments: Altimeter
Under what conditions does the altimeter provide correct readings?
- Standard sea level barometric pressure of 29.92 inches of mercury (“Hg).
- Standard sea level free air temperature of 15°C (59°F).
- Standard pressure and temperature decrease with altitude.
Pitot-Static Flight Instruments: Altimeter
What happens when atmospheric conditions are nonstandard?
The altimeter must be adjusted using the barometric pressure setting.
Pitot-Static Flight Instruments: Altimeter
What is the barometric scale on the altimeter also called?
The Kollsman window.
Pitot-Static Flight Instruments: Altimeter
How does the barometric scale affect the altimeter reading?
Adjusting the barometric pressure setting corrects the indicated altitude to account for nonstandard pressure conditions.
Pitot-Static Flight Instruments: Altimeter
What is the “indicated altitude”?
The altitude read directly from the altimeter after the barometric pressure is set in the Kollsman window.
Altimeter, Effect of Nonstandard Pressure and Temperature
What happens to the altimeter reading when flying from high to low pressure without adjustment?
- The actual altitude is lower than the indicated altitude.
- Memory aid: “From high to low, look out below.”
Altimeter, Effect of Nonstandard Pressure and Temperature
What happens when flying from low to high pressure without adjustment?
The actual altitude is higher than the indicated altitude.
Altimeter, Effect of Nonstandard Pressure and Temperature
What is the danger of altimeters unable to set pressures above 31.00 “Hg?
The aircraft’s actual altitude is higher than the altimeter indicates.
Altimeter, Effect of Nonstandard Pressure and Temperature
What is the recommendation when barometric pressure falls below 28.00 “Hg?
Flight operations are not recommended for aircraft unable to set the actual altimeter setting.
Altimeter, Effect of Nonstandard Pressure and Temperature
How does colder-than-standard temperature affect true altitude?
True altitude is lower than the indicated altitude.
Memory aid: “From hot to cold, look out below.”
Altimeter, Effect of Nonstandard Pressure and Temperature
How does warmer-than-standard temperature affect true altitude?
True altitude is higher than the indicated altitude.
Altimeter, Effect of Nonstandard Pressure and Temperature
Why is colder-than-standard temperature a concern in mountainous terrain?
It places the aircraft lower than the altimeter indicates, increasing the risk of terrain collision.
Altimeter, Effect of Nonstandard Pressure and Temperature
What should a pilot do when flying in cold temperatures for terrain clearance?
Fly at a higher indicated altitude than usual.
Altimeter, Effect of Nonstandard Pressure and Temperature
What tool can be used to compute altitude corrections for temperature?
A navigation computer.
Altimeter, Effect of Nonstandard Pressure and Temperature
What are the memory aids for pressure and temperature effects?
- Pressure: “From high to low, look out below.”
- Temperature: “From hot to cold, look out below.”
Pitot-Static Flight Instruments: Setting the Altimeter
What is the purpose of the altimeter setting window (Kollsman window)?
It adjusts the altimeter for variations in atmospheric pressure.
Pitot-Static Flight Instruments: Setting the Altimeter
How is the altimeter setting obtained?
From ATC, AWOS/ASOS, or ATIS broadcasts.
Pitot-Static Flight Instruments: Setting the Altimeter
What is the definition of “altimeter setting”?
Station pressure reduced to sea level.
Pitot-Static Flight Instruments: Setting the Altimeter
Why must the altimeter setting be updated en route?
To account for changes in pressure and ensure accurate altitude readings.
Pitot-Static Flight Instruments: Setting the Altimeter
What happens when the actual pressure is lower than the set altimeter pressure?
The actual altitude is lower than the indicated altitude.
Pitot-Static Flight Instruments: Setting the Altimeter
What happens when the actual pressure is higher than the set altimeter pressure?
The actual altitude is higher than the indicated altitude.
Pitot-Static Flight Instruments: Setting the Altimeter
What does “GOING FROM HIGH TO LOW, LOOK OUT BELOW” mean?
Flying from a high-pressure to a low-pressure area without adjustment results in flying lower than indicated.
Pitot-Static Flight Instruments: Setting the Altimeter
What is the altimeter error when transitioning from 29.94 “Hg to 29.69 “Hg?
- 250 feet lower than indicated.
- Calculation: 29.94 − 29.69 = 0.25 × 1000 = 250
Pitot-Static Flight Instruments: Setting the Altimeter
How do you compute the corrected altitude when pressure settings change?
- Subtract the calculated difference from the indicated altitude.
- Calculation: 29.94 − 29.69 = 0.25 × 1000 = 250
- Example: 2,600 − 250 = 2,350
Pitot-Static Flight Instruments: Setting the Altimeter
What happens when transitioning from 29.94 “Hg to 30.56 “Hg?
- 620 feet higher than indicated.
- Calculation: 29.94 − 30.56 = −0.62 × 1000 = −620
- Subtraction of a negative number results in addition:
2,600 − (−620) = 3,220
Pitot-Static Flight Instruments: Setting the Altimeter
Why is maintaining the correct altimeter setting critical for safety?
Prevents altitude deviations that can lead to terrain or obstacle collisions.
Pitot-Static Flight Instruments: Setting the Altimeter
What is the relationship between 1 inch of pressure and altitude?
1 inch of pressure = approximately 1,000 feet of altitude.
Pitot-Static Flight Instruments: Setting the Altimeter
Why should pilots allow extra altitude over mountainous terrain?
To account for possible altimeter errors and downdrafts.
Pitot-Static Flight Instruments: Setting the Altimeter
What should you always do when computing altitude deviations?
Use the original setting as the top number for subtraction.
Pitot-Static Flight Instruments: Setting the Altimeter
How do you interpret a negative difference in pressure settings?
Subtracting a negative difference is equivalent to adding it to the indicated altitude.
Pitot-Static Flight Instruments: Altimeter Operation
What are the two means by which the altimeter pointers can be moved?
- A change in air pressure
- An adjustment to the barometric scale
Pitot-Static Flight Instruments: Altimeter Operation
How does the altimeter respond to a decrease in pressure?
It indicates an increase in altitude.
Pitot-Static Flight Instruments: Altimeter Operation
How does the altimeter respond to an increase in pressure?
It indicates a decrease in altitude.
Pitot-Static Flight Instruments: Altimeter Operation
Why is the altimeter important for pilots?
It ensures the aircraft is flying high enough to clear terrain and obstacles, especially in restricted visibility.
Pitot-Static Flight Instruments: Altimeter Operation
What happens if the pressure changes from 29.98 “Hg to 29.68 “Hg on the ground?
The altimeter shows an increase of 300 feet in altitude.
Pitot-Static Flight Instruments: Altimeter Operation
How can the altimeter be reset to display the correct altitude on the ground?
Adjust the barometric scale to the current pressure (e.g., 29.68 “Hg).
Pitot-Static Flight Instruments: Altimeter Operation
Why might the altimeter show a higher altitude after an overnight pressure drop?
The altimeter interprets the pressure drop as a climb.
Pitot-Static Flight Instruments: Altimeter Operation
What happens to true altitude if the altimeter setting remains constant while flying into lower pressure?
The true altitude decreases.
Pitot-Static Flight Instruments: Altimeter Operation
Why must pilots be especially vigilant about altitude in low visibility conditions?
To ensure clearance of terrain and obstacles.
Pitot-Static Flight Instruments: Altimeter Operation
How does maintaining the correct altitude reduce the risk of midair collisions?
It ensures compliance with air traffic rules and proper altitude separation.
Pitot-Static Flight Instruments: Altimeter Operation
What is the relationship between barometric pressure and altitude?
It ensures compliance with air traffic rules and proper altitude separation.
Pitot-Static Flight Instruments: Altimeter Operation
Why is it important to adjust the barometric scale regularly during flight?
To maintain accurate altitude indications relative to changing atmospheric pressure.
Pitot-Static Flight Instruments: Types of Altitude
Indicated Altitude:
Directly read from the altimeter (uncorrected) when set to the current altimeter setting.
Pitot-Static Flight Instruments: Types of Altitude
True Altitude:
- Vertical distance above mean sea level (MSL)—the actual altitude.
- Used for airport elevations, obstacles, and terrain as depicted on aeronautical charts.
Pitot-Static Flight Instruments: Types of Altitude
Absolute Altitude:
Vertical distance above ground level (AGL).
Pitot-Static Flight Instruments: Types of Altitude
Pressure Altitude:
- Altitude shown when the altimeter is set to 29.92 “Hg.
- Used for performance calculations (e.g., density altitude, true airspeed).
Pitot-Static Flight Instruments: Types of Altitude
Density Altitude:
- Pressure altitude corrected for nonstandard temperature.
- Directly affects aircraft performance:
Higher density altitude → Reduced engine and airfoil efficiency.
Lower density altitude → Improved performance.
Pitot-Static Flight Instruments: Types of Altitude
Higher Density Altitude:
- Fewer air molecules (low pressure + high temperature).
- Requires longer takeoff roll, reduced climb rate, and overall decreased performance.
Pitot-Static Flight Instruments: Types of Altitude
Lower Density Altitude:
- Denser air (low temperature).
- Shorter takeoff roll, better climb rate, and enhanced performance.
Pitot-Static Flight Instruments: Altimeter Instrument Check
What should a pilot check on the altimeter before each flight?
Proper indications by setting the barometric scale to the current altimeter setting.
Pitot-Static Flight Instruments: Altimeter Instrument Check
Where can the current altimeter setting be obtained?
From ATC, FSS, ATIS, AWOS, or ASOS.
Pitot-Static Flight Instruments: Altimeter Instrument Check
What should the altimeter indicate when set to the correct barometric pressure in a pre-flight check?
The surveyed field elevation of the airport.
Pitot-Static Flight Instruments: Altimeter Instrument Check
What is the acceptable deviation for the altimeter indication?
No more than 75 feet from the surveyed field elevation.
Pitot-Static Flight Instruments: Altimeter Instrument Check
What should be done if the altimeter deviates more than 75 feet?
Refer the instrument to a certificated repair station for recalibration.
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What does the VSI indicate?
Whether the aircraft is climbing, descending, or in level flight, with the rate shown in feet per minute (fpm).
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What are the two types of information displayed by the VSI?
- Trend Information: Immediate indication of an increase or decrease in climb/descent rate.
- Rate Information: Stabilized rate of altitude change in fpm.
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
How does the VSI operate?
It uses static pressure as a differential pressure instrument with a diaphragm connected to the static line and a case connected through a restricted orifice.
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What causes the VSI needle to move?
A pressure differential between the diaphragm (immediate pressure changes) and the case (delayed pressure changes).
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What is the time delay in VSI readings called?
Lag—the time it takes for the needle to stabilize and show an accurate rate of climb or descent (6–9 seconds).
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What instrument reduces the lag of a typical VSI?
Instantaneous Vertical Speed Indicator (IVSI), which uses accelerometers.
Pitot-Static Flight Instruments: Vertical Speed Indicator (VSI)
What can extend the lag period in VSI readings?
Rough control inputs and turbulence.
Pitot-Static Flight Instruments: VSI Instrument Check
What should the VSI indicate during a preflight check?
It should indicate a near-zero reading.
Pitot-Static Flight Instruments: VSI Instrument Check
What should you do if the VSI shows a value other than zero before takeoff?
Treat that value as the zero mark for reference during flight.
Pitot-Static Flight Instruments: VSI Instrument Check
What should the VSI indicate immediately after takeoff?
The VSI should trend upward, showing a positive rate of climb.
Pitot-Static Flight Instruments: VSI Instrument Check
What should the VSI indicate during a stabilized climb?
A steady rate of climb appropriate to the aircraft’s performance.
Pitot-Static Flight Instruments: ASI
What does the Airspeed Indicator (ASI) measure?
The difference between pitot (dynamic) pressure and static pressure.
Pitot-Static Flight Instruments: ASI
Which two systems does the ASI utilize?
The pitot system and the static system.
Pitot-Static Flight Instruments: ASI
What is Indicated Airspeed (IAS)?
The direct reading from the ASI, uncorrected for density, installation, or instrument errors.
Pitot-Static Flight Instruments: ASI
What is Calibrated Airspeed (CAS)?
IAS corrected for installation and instrument errors.
Pitot-Static Flight Instruments: ASI
When are IAS and CAS approximately the same?
At cruising and higher airspeeds.
Pitot-Static Flight Instruments: ASI
What is True Airspeed (TAS)?
CAS corrected for altitude and nonstandard temperature.
Pitot-Static Flight Instruments: ASI
How does TAS change with altitude?
TAS increases as altitude increases for the same CAS.
Pitot-Static Flight Instruments: ASI
How can you approximate TAS using a rule of thumb?
Add 2% to CAS for every 1,000 feet of altitude.
Pitot-Static Flight Instruments: ASI
What is Groundspeed (GS)?
- TAS adjusted for wind;
- increases with a tailwind, decreases with a headwind.
Pitot-Static Flight Instruments: Airspeed Indicator Markings
What is the purpose of the color-coded markings on an ASI?
To quickly indicate airspeed limitations for safe aircraft operation.
Pitot-Static Flight Instruments: Airspeed Indicator Markings
What does the White Arc represent?
Flap operating range:
* Lower limit (VS0): Stalling speed in the landing configuration.
* Upper limit (VFE): Maximum speed with flaps extended
Pitot-Static Flight Instruments: Airspeed Indicator Markings
What does the Green Arc represent?
The normal operating range:
* Lower limit (VS1): Stalling speed in a specified configuration (e.g., gear up, flaps up).
* Upper limit (VN0): Maximum structural cruising speed (do not exceed except in smooth air).
Pitot-Static Flight Instruments: Airspeed Indicator Markings
What does the Yellow Arc represent?
Caution range—fly only in smooth air and with caution.
Pitot-Static Flight Instruments: Airspeed Indicator Markings
What does the Red Line (VNE) indicate?
Never exceed speed—operating above this speed is prohibited due to risk of structural damage or failure.
Pitot-Static Flight Instruments: ASI, Instrument Check
What should the ASI read prior to takeoff?
Zero, unless strong wind is blowing directly into the pitot tube, which may cause a slightly higher reading.
Pitot-Static Flight Instruments: ASI, Instrument Check
What should be checked on the ASI during takeoff?
Ensure the airspeed is increasing at an appropriate rate.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What can cause blockage in the pitot-static system?
Moisture (including ice), dirt, or insects.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What happens if the pitot tube is blocked but the drain hole remains open?
The ASI reading decreases to zero as the system vents to ambient pressure.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What occurs if both the pitot tube opening and drain hole are blocked?
The ASI freezes at the airspeed where the blockage occurred, unaffected by changes in actual airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
How does a blocked static port affect the ASI, altimeter, and VSI?
It causes errors in all three instruments.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What does the ASI rely on to function?
Both dynamic pressure (from the pitot tube) and static pressure (from the static port).
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
How does the ASI behave if the static port is clear but the pitot tube is blocked?
ASI shows inaccurate changes based on altitude changes rather than airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What is the result of a climb with a blocked pitot tube and clear static port?
The ASI falsely indicates an increase in airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What is the result of a descent with a blocked pitot tube and clear static port?
The ASI falsely indicates a decrease in airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
How can a pilot prevent pitot tube blockage due to visible moisture?
Use pitot heat as specified in the AFM/POH.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What happens to the ASI if the static system is blocked but the pitot tube remains clear?
The ASI continues to operate but gives inaccurate readings:
- Above the blocked altitude: Indicates lower than actual airspeed.
- Below the blocked altitude: Indicates higher than actual airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
Why does a blocked static port cause errors in the ASI?
Trapped static pressure remains constant, altering the relationship between static and dynamic pressure.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
How does a blocked static system affect the altimeter?
The altimeter freezes at the altitude where the blockage occurred.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What is the effect of a blocked static system on the VSI?
The VSI shows a continuous zero indication.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What happens to the ASI when the aircraft climbs with a blocked static system?
The ASI falsely indicates a decrease in airspeed.
Pitot-Static Flight Instruments: Blockage of the Pitot-Static System
What happens to the ASI when the aircraft descends with a blocked static system?
The ASI falsely indicates an increase in airspeed.
Electronic Flight Display (EFD)
What is an Electronic Flight Display (EFD)?
A modern “glass cockpit” system that includes Primary Flight Displays (PFDs) and Multi-Function Displays (MFDs), consolidating traditional flight instruments into digital screens.
Electronic Flight Display (EFD)
What is the purpose of an Airspeed Tape on a PFD?
Displays airspeed as a vertical speed tape with markings for critical speeds (e.g., VX, VY, VR), color-coded ranges, and TAS at the bottom.
Electronic Flight Display (EFD)
How is the Attitude Indicator improved on an EFD?
It spans the entire width of the PFD, offering better reference for all phases of flight, with data from the Attitude Heading and Reference System (AHRS).
Electronic Flight Display (EFD)
How is altitude displayed on a PFD?
Using a vertical tape on the right side of the PFD, with current altitude shown in a black box in 20-foot increments.
Electronic Flight Display (EFD)
What additional feature does the VSI have on an EFD?
Displays vertical speed as an arced indicator or vertical tape, often with a vertical speed bug for precise reference.
Electronic Flight Display (EFD)
Where is the Heading Indicator located on a PFD, and how does it work?
Below the artificial horizon, modeled after an HSI, with data from a magnetometer via the AHRS.
Electronic Flight Display (EFD)
What is unique about the Turn Indicator on a PFD?
A sliding bar moves below the triangle to show deflection, with data from AHRS accelerometers for coordinated flight.
Electronic Flight Display (EFD)
Where is the Tachometer typically located in an EFD system?
On the MFD, but it can display on the PFD in case of screen failure.
Electronic Flight Display (EFD)
What does the Slip/Skid Indicator look like on a PFD?
A horizontal line below the roll pointer, with one bar width off-center equal to one ball width displacement.
Electronic Flight Display (EFD)
How is the Turn Rate Indicator displayed on a PFD?
As a trend line above the compass card, with tick marks denoting standard-rate or half standard-rate turns.
Electronic Flight Display (EFD)
What does the Air Data Computer (ADC) do?
Processes pitot-static inputs to compute and display airspeed, altitude, and outside air temperature on the PFD. It also provides data to the autopilot.
Electronic Flight Display (EFD)
What are Trend Vectors on an EFD?
Magenta lines on the airspeed and altitude tapes that show a 6-second projection of changes, helping pilots control airspeed and altitude.
Gyroscopic Flight Instruments
Which instruments commonly utilize gyroscopes?
Turn coordinator, heading indicator, and attitude indicator.
Gyroscopic Flight Instruments
What is a gyroscope?
A spinning wheel or rotor designed and mounted to utilize gyroscopic properties.
Gyroscopic Flight Instruments
What are two key design characteristics of a gyroscope?
Great weight for its size (high density) and high-speed rotation with low friction bearings.
Gyroscopic Flight Instruments
What are the two types of gyroscope mountings?
- Freely (universally) mounted: Free to rotate in any direction about its center of gravity, with three planes of freedom.
- Restricted (semi-rigidly) mounted: One plane of freedom is fixed relative to the base.
Gyroscopic Flight Instruments
What are the two fundamental properties of gyroscopic action?
- Rigidity in space: A gyroscope remains fixed in its plane of rotation.
- Precession: The reaction to a force applied to the spinning mass occurs 90° ahead in the direction of rotation.
Gyroscopic Flight Instruments
What does “three planes of freedom” mean for a gyroscope?
The gyroscope is free to rotate in any plane relative to its base.
Gyroscopic Flight Instruments
Why is low friction important for a gyroscope?
It ensures smooth, accurate, and consistent operation of the gyroscopic instruments.
Gyroscopic Flight Instruments
What is rigidity in space?
The principle that a gyroscope remains in a fixed position in the plane in which it is spinning.
Gyroscopic Flight Instruments
What is an example of rigidity in space?
A bicycle wheel becomes more stable in its plane of rotation as its speed increases, making the bicycle stable at higher speeds and unstable at lower speeds.
Gyroscopic Flight Instruments
What happens to the gyroscope if the gimbal rings are tilted or moved?
The gyroscope remains in its original plane of rotation despite the movement of the gimbal rings.
Gyroscopic Flight Instruments
What is precession in gyroscopic instruments?
Precession is the tilting or turning of a gyroscope in response to a deflective force, with the reaction occurring 90° later in the direction of rotation.
Gyroscopic Flight Instruments
How does precession help measure the rate of turn?
Precession senses the pressure created by a directional change, allowing the gyroscope to determine the rate of turn.
Gyroscopic Flight Instruments
How is the rate of precession related to rotor speed and deflective force?
- It is inversely proportional to rotor speed.
- It is directly proportional to the deflective force.
Gyroscopic Flight Instruments
How does precession relate to a bicycle’s movement?
Leaning left applies a force to the top of a clockwise-rotating wheel. The reaction occurs 90° later, pushing the wheel left, causing the bicycle to turn left.
Gyroscopic Flight Instruments
What errors can precession cause in gyroscopic instruments?
Precession can cause the gyro to be displaced from its plane of rotation due to friction or other forces, requiring instruments like the heading indicator to be realigned during flight.
Gyroscopic Flight Instruments
What are the power sources for gyroscopic instruments in aircraft?
Gyros can be powered by vacuum, pressure, or the electrical system. Most aircraft use a combination to ensure redundancy.
Gyroscopic Flight Instruments
Which instruments are typically vacuum or pressure-powered?
The attitude indicator and heading indicator are often powered by vacuum or pressure systems.
Gyroscopic Flight Instruments
Which instrument is typically powered by the electrical system?
The turn coordinator is usually electrically powered.
Gyroscopic Flight Instruments
How does a vacuum or pressure system spin gyros?
Air is drawn against the rotor vanes, spinning the gyro at high speed, similar to a turbine.
Gyroscopic Flight Instruments
What is the typical operating range for vacuum or pressure systems?
Between 4.5” Hg and 5.5” Hg.
Gyroscopic Flight Instruments
What five components are included in a typical vacuum system?
- Engine-driven vacuum pump
- Relief valve
- Air filter
- Vacuum gauge
- Tubing connections
Gyroscopic Flight Instruments
What does the vacuum gauge measure?
The vacuum gauge measures suction in inches of mercury (less than ambient pressure).
Gyroscopic Flight Instruments
Why is it important to monitor vacuum pressure?
Low vacuum pressure can cause gyroscopic instruments (attitude and heading indicators) to become unreliable.
Gyroscopic Flight Instruments
What happens when vacuum pressure drops below normal?
The gyroscopic instruments may become unstable and inaccurate.
Gyroscopic Flight Instruments
How can pilots monitor low vacuum pressure?
By routinely cross-checking the vacuum gauge and looking for warning lights indicating low pressure.
Gyroscopic Flight Instruments: Turn Indicators
What are the two types of turn indicators used in aircraft?
Turn-and-slip indicators and turn coordinators.
Gyroscopic Flight Instruments: Turn Indicators
What does the turn-and-slip indicator measure?
It shows the rate of turn in degrees per second.
Gyroscopic Flight Instruments: Turn Indicators
How is the turn coordinator different from the turn-and-slip indicator?
The turn coordinator is mounted at an angle (canted) and initially shows roll rate, then indicates rate of turn when stabilized.
Gyroscopic Flight Instruments: Turn Indicators
What do both turn indicators show?
- Turn direction
- Turn quality (coordination)
- Serve as a backup for bank information if the attitude indicator fails.
Gyroscopic Flight Instruments: Turn Indicators
What tool is used to achieve coordinated flight?
The inclinometer, which consists of a liquid-filled curved tube with a ball inside.
Gyroscopic Flight Instruments: Turn Indicators
What does the ball in the inclinometer indicate?
The quality of the turn:
- Centered ball: Coordinated turn
- Ball inside the turn: Slip
- Ball outside the turn: Skid
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
How does the gyro in the turn-and-slip indicator rotate?
It rotates in the vertical plane corresponding to the aircraft’s longitudinal axis.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
What limits the gyro’s movement in the turn-and-slip indicator?
A single gimbal and a spring that maintains a center position.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
How does precession affect the turn-and-slip indicator?
A yawing force causes the gyro to tilt left or right, as seen from the pilot seat.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
What does the turn-and-slip indicator use to show the direction and rate of turn?
A turn needle.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
Can the turn-and-slip indicator gyro tumble off its rotational axis? Why or why not?
No, because of the restraining springs.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
What happens if extreme forces are applied to a gyro?
The gyro is displaced from its normal plane of rotation, making its indications invalid.
Gyroscopic Flight Instruments: Turn-and-Slip Indicator
What are pitch and bank limits in relation to the gyro?
Exceeding specific pitch and bank limits can induce a gyro tumble in certain instruments.
Gyroscopic Flight Instruments: Turn Coordinator
How is the gimbal in a turn coordinator mounted?
It is canted, allowing the gyro to sense both rate of roll and rate of turn.
Gyroscopic Flight Instruments: Turn Coordinator
What happens to the miniature aircraft during a roll?
It banks in the direction of the roll, with a steeper bank for rapid rolls compared to slower rolls.
Gyroscopic Flight Instruments: Turn Coordinator
What is the purpose of the turn coordinator in flight?
It is used to establish and maintain a standard-rate turn by aligning the miniature aircraft with the turn index.
Gyroscopic Flight Instruments: Turn Coordinator
What do the marks on the turn coordinator face indicate?
- The first mark indicates a wings-level, zero rate of turn.
- The second marks on both sides indicate a standard-rate turn.
Gyroscopic Flight Instruments: Turn Coordinator
What is the definition of a standard-rate turn?
A turn rate of 3° per second.
Gyroscopic Flight Instruments: Turn Coordinator
Does the turn coordinator show a specific angle of bank?
No, it indicates only the rate and direction of the turn.
Gyroscopic Flight Instruments: Inclinometer
What does the inclinometer depict?
Aircraft yaw (side-to-side movement of the nose).
Gyroscopic Flight Instruments: Inclinometer
How is coordinated flight shown on the inclinometer?
The ball rests centered between the reference lines due to gravity.
Gyroscopic Flight Instruments: Inclinometer
How do you center the ball on the inclinometer?
Apply rudder pressure on the side where the ball is deflected using the rule: “step on the ball.”
Gyroscopic Flight Instruments: Inclinometer
What does the ball’s position indicate in a slip?
The ball moves inside the turn, indicating the rate of turn is too slow for the angle of bank.
Gyroscopic Flight Instruments: Inclinometer
What does the ball’s position indicate in a skid?
The ball moves outside the turn, indicating the rate of turn is too fast for the angle of bank.
Gyroscopic Flight Instruments: Inclinometer
How do you correct a slip?
Decrease bank and/or increase the rate of turn.
Gyroscopic Flight Instruments: Inclinometer
How do you correct a skid?
Increase bank and/or decrease the rate of turn.
Gyroscopic Flight Instruments: Inclinometer
What is a yaw string?
A string or yarn attached to the center of the windscreen to indicate coordination in flight.
Gyroscopic Flight Instruments: Inclinometer
What does the yaw string indicate in coordinated flight?
The string trails straight back over the windscreen.
Gyroscopic Flight Instruments: Inclinometer
What does the yaw string do during a slip or skid?
It moves to the right or left, depending on the direction of the slip or skid.
Gyroscopic Flight Instruments: Inclinometer
How can a yaw string help a pilot?
It provides a simple visual indication of coordinated or uncoordinated flight.
Gyroscopic Flight Instruments: Instrument Check
What should you check for in the inclinometer during preflight?
Ensure it is full of fluid, has no air bubbles, and the ball rests at its lowest point.
Gyroscopic Flight Instruments: Instrument Check
What should the turn coordinator indicate during taxi?
A turn in the correct direction, with the ball moving opposite the direction of the turn.
Gyroscopic Flight Instruments: Instrument Check
What does the ball in the inclinometer do during a turn while taxiing?
It moves opposite the direction of the turn.
Gyroscopic Flight Instruments: Instrument Check
Why is checking the turn coordinator during taxi important?
To ensure proper functionality of the turn coordinator and inclinometer for flight.
Gyroscopic Flight Instruments: Attitude Indicator
What does the attitude indicator display?
A miniature aircraft and a horizon bar that show the aircraft’s attitude relative to the true horizon.
Gyroscopic Flight Instruments: Attitude Indicator
How does the attitude indicator’s gyro operate?
It spins in a horizontal plane and uses the principle of rigidity in space, resisting deflection.
Gyroscopic Flight Instruments: Attitude Indicator
What is the function of the adjustment knob on the attitude indicator?
It aligns the miniature aircraft with the horizon bar to match the pilot’s line of vision.
Gyroscopic Flight Instruments: Attitude Indicator
What are the typical pitch and bank limits of an attitude indicator?
Bank limits: 100°–110°; Pitch limits: 60°–70° (varies by model).
Gyroscopic Flight Instruments: Attitude Indicator
What happens if the pitch or bank limits are exceeded?
The indicator may peg (stop) or tumble, leading to erroneous indications.
Gyroscopic Flight Instruments: Attitude Indicator
How should the banking scale on the attitude indicator be interpreted?
Use it to determine the degree of bank, while the miniature aircraft’s position relative to the horizon bar indicates the direction of bank.
Gyroscopic Flight Instruments: Attitude Indicator
What makes the attitude indicator a vital instrument?
It provides realistic and reliable approximations of the aircraft’s attitude.
Gyroscopic Flight Instruments: Attitude Indicator
What is the primary purpose of the heading indicator?
To facilitate use of the magnetic compass by providing stable and accurate heading information, unaffected by compass errors.
Gyroscopic Flight Instruments: Attitude Indicator
On what principle does the heading indicator operate?
The principle of rigidity in space. The gyro remains fixed while the aircraft rotates around it.
Gyroscopic Flight Instruments: Attitude Indicator
How does the heading indicator display heading information?
The compass card attached to the gyro remains stable, and the aircraft’s case rotates around it, showing heading changes.
Gyroscopic Flight Instruments: Attitude Indicator
Why does the heading indicator drift over time?
Due to precession from friction and the Earth’s rotation (15° per hour).
Gyroscopic Flight Instruments: Attitude Indicator
How often should the heading indicator be aligned with the magnetic compass?
Regularly during flight to account for drift.
Gyroscopic Flight Instruments: Attitude Indicator
What does HSI stand for?
Horizontal Situation Indicator
Gyroscopic Flight Instruments: Attitude Indicator
What is a horizontal situation indicator (HSI)?
A heading indicator that receives a magnetic north reference from a magnetometer, usually requiring no manual adjustment.
Gyroscopic Flight Instruments: Attitude Indicator
What causes excessive drift in the heading indicator?
Worn bearings, dirt, or improper lubrication inside the instrument.
Gyroscopic Flight Instruments: AHRS
What does AHRS stand for?
Attitude and Heading Reference System
Gyroscopic Flight Instruments: AHRS
What system has replaced free-spinning gyros in modern aircraft?
The Attitude and Heading Reference System (AHRS).
Gyroscopic Flight Instruments: AHRS
What does the AHRS provide to the PFD?
Attitude information for pitch and bank display and heading information.
Gyroscopic Flight Instruments: AHRS
How does the AHRS determine heading information?
From a magnetometer, which senses the Earth’s lines of magnetic flux.
Gyroscopic Flight Instruments: AHRS
What is the primary benefit of AHRS over traditional gyros?
AHRS can function at any attitude without tumbling.
Gyroscopic Flight Instruments: AHRS
What does AHRS replace in electronic flight displays?
Free-spinning gyros with solid-state laser systems.
Gyroscopic Flight Instruments: The Flux Gate Compass System
What principle does the flux gate compass system use?
Current induction by the Earth’s magnetic field.
Gyroscopic Flight Instruments: The Flux Gate Compass System
What is the flux valve made of?
A small, segmented ring of soft iron that readily accepts magnetic flux.
Gyroscopic Flight Instruments: The Flux Gate Compass System
What happens when the AC coil reaches its peak current?
The magnetism produced prevents the frame from accepting the Earth’s magnetic flux.
Gyroscopic Flight Instruments: The Flux Gate Compass System
What occurs when the AC coil current reverses?
The frame is demagnetized and can accept flux from the Earth’s magnetic field.
Gyroscopic Flight Instruments: The Flux Gate Compass System
How does the flux gate compass detect heading changes?
Current flows in the three coils of the flux valve, varying with the aircraft’s heading.
Gyroscopic Flight Instruments: The Flux Gate Compass System
What instruments does the flux gate compass system drive?
The radio magnetic indicator (RMI) or the horizontal situation indicator (HSI).
Gyroscopic Flight Instruments: The Flux Gate Compass System
How are the coils in the flux valve connected to the instrument?
Through a synchro inside the instrument case, which rotates the dial.
Gyroscopic Flight Instruments: Remote Indicating Compass
What are the two main panel-mounted components of a remote indicating compass system?
The pictorial navigation indicator (HSI) and the slaving control and compensator unit.
Gyroscopic Flight Instruments: Remote Indicating Compass
What does the slaving meter on the slaving control unit indicate?
The difference between the displayed heading and the magnetic heading.
Gyroscopic Flight Instruments: Remote Indicating Compass
What is the purpose of the slaving control’s “free gyro” mode?
It allows the compass card to be manually adjusted using the heading-drive buttons.
Gyroscopic Flight Instruments: Remote Indicating Compass
Where is the magnetic slaving transmitter typically mounted, and why?
In a wingtip to minimize magnetic interference.
Gyroscopic Flight Instruments: Remote Indicating Compass
What does the magnetic slaving transmitter contain?
The flux valve, which senses direction.
Gyroscopic Flight Instruments: Remote Indicating Compass
How does the magnetic slaving transmitter interact with the HSI?
It sends signals to a torque motor in the HSI, which aligns the gyro with the magnetic heading.
Gyroscopic Flight Instruments: Remote Indicating Compass
How often should the heading indicator be checked and reset in aircraft without slaved gyros?
Approximately every 15 minutes during straight-and-level, constant-speed flight.
Gyroscopic Flight Instruments: Remote Indicating Compass
What are the pitch and bank limits for most heading indicators in light aircraft?
Approximately 55° pitch and 55° bank.
Gyroscopic Flight Instruments: Remote Indicating Compass
What happens if the heading indicator exceeds its pitch or bank limits?
It tumbles or spills and must be reset using the caging knob.
Gyroscopic Flight Instruments: Remote Indicating Compass
What is a common indicator of low vacuum in the system powering the heading indicator?
A warning light or a vacuum gauge showing insufficient suction.
Gyroscopic Flight Instruments: Instrument Check
What should be checked for when the gyro spools up?
Ensure there are no abnormal sounds.
Gyroscopic Flight Instruments: Instrument Check
What should the heading indicator do while taxiing?
It should indicate turns in the correct direction, and precession should be normal.
Gyroscopic Flight Instruments: Instrument Check
What might occur at idle power settings with vacuum-powered gyroscopic instruments?
They might not be at operating speed, causing faster-than-normal precession.
Angle of Attack Indicators
What is the primary purpose of an AOA indicator?
To provide situational awareness about the aerodynamic health of the airfoil, or stall margin awareness.
Angle of Attack Indicators
What does the AOA indicator measure?
The current angle of attack (AOA) and the margin to the critical AOA (stall point).
Angle of Attack Indicators
Why is speed alone unreliable for stall prevention?
An airplane can stall at any speed, but it always stalls at the same critical AOA for a given configuration.
Angle of Attack Indicators
What five factors do NOT affect the critical AOA?
- Weight
- Bank angle
- Temperature
- Density altitude
- Center of gravity
Angle of Attack Indicators
What is the benefit of an AOA indicator in General Aviation aircraft?
It provides a visual representation of the current AOA and the airplane’s proximity to the critical AOA, enhancing energy state awareness (balance of airspeed, altitude, drag, and thrust).
Angle of Attack Indicators
What does the energy state of an airplane represent?
The balance between airspeed, altitude, drag, and thrust, showing how efficiently the airfoil is operating.
Compass Systems
What creates the Earth’s magnetic field?
The Earth acts as a giant magnet, surrounded by invisible lines of magnetic flux that extend from the magnetic North Pole to the magnetic South Pole.
Compass Systems
What are the two key characteristics of magnetic flux lines?
- A magnet free to rotate will align with them.
- An electrical current is induced in a conductor that crosses them.
Compass Systems
What aircraft instruments utilize magnetic flux lines?
Most direction indicators, such as magnetic compasses, use these flux lines to provide heading information.
Compass Systems: Magnetic Compass
What is a magnetic compass used for in aviation?
It indicates direction and is a required instrument for VFR and IFR flight under 14 CFR part 91.
Compass Systems: Magnetic Compass
What are the two poles of a magnet?
North and South poles. Unlike poles attract; like poles repel.
Compass Systems: Magnetic Compass
How does the magnetic compass work?
Two small magnets attached to a metal float align with the Earth’s magnetic field, and a graduated card shows direction.
Compass Systems: Magnetic Compass
What is the function of the compass fluid?
It provides buoyancy for the float, reduces oscillations, and allows the float to tilt up to 18°.
Compass Systems: Magnetic Compass
How is the compass card graduated?
- Marked with cardinal directions (N, E, S, W)
- Numbers every 30°, omitting the final zero (e.g., 3 = 30°, 33 = 330°).
Compass Systems: Magnetic Compass
What prevents fluid damage due to temperature changes?
A flexible diaphragm or metal bellows allows for expansion and contraction.
Compass Systems: Magnetic Compass
Why can the magnetic compass be confusing to read?
The card remains stationary while the pilot and compass housing rotate, making the numbers appear backward.
Compass Systems: Magnetic Compass
How many degrees do the long marks on a compass represent?
10°
Compass Systems: Magnetic Compass
How many degrees do the short marks on a compass represent?
5°
Compass Systems: Magnetic Compass Induced Errors, Variation
What is variation in navigation?
The angular difference between true directions (geographic poles) and magnetic directions (magnetic poles).
Compass Systems: Magnetic Compass Induced Errors, Variation
What are isogonic lines?
Lines on a chart that show the degrees of variation in a specific area.
Compass Systems: Magnetic Compass Induced Errors, Variation
What is the agonic line?
A line where the geographic North Pole and magnetic North Pole align, resulting in no variation.
Compass Systems: Magnetic Compass Induced Errors, Variation
How do you correct for variation when flying in areas with variation?
- West variation: Add the variation to the true course.
- East variation: Subtract the variation from the true course.
Compass Systems: Magnetic Compass Induced Errors, Variation
Give an example of correcting for variation.
- In Washington, D.C. (10° west variation), to fly a true course of 180°, fly a magnetic course of 190°.
- In Los Angeles (14° east variation), to fly a true course of 180°, fly a magnetic course of 166°.
Compass Systems: Magnetic Compass Induced Errors, Variation
Does variation change with the heading of the aircraft?
No, variation remains constant anywhere along the same isogonic line.
Compass Systems: Magnetic Compass Induced Errors, Deviation
What is deviation in a magnetic compass?
Deviation is an error caused by magnetic fields in the aircraft, such as from electrical current, magnetized parts, or interference with the Earth’s magnetic field.
Compass Systems: Magnetic Compass Induced Errors, Deviation
How does deviation differ from variation?
- Deviation: Depends on the aircraft’s heading and is caused by onboard magnetic fields.
- Variation: Depends on geographic location and the difference between true and magnetic north.
Compass Systems: Magnetic Compass Induced Errors, Deviation
What is “swinging the compass”?
A maintenance procedure performed by an AMT to minimize compass deviation by aligning the aircraft with known headings on a compass rose and adjusting compensator magnets.
Compass Systems: Magnetic Compass Induced Errors, Deviation
What is a compass rose?
A series of lines marked every 30° on an airport ramp, oriented to magnetic north, used for minimizing magnetic deviation.
Compass Systems: Magnetic Compass Induced Errors, Deviation
How is deviation corrected in the compass?
Using a compensator assembly with adjustable magnets for east-west and north-south headings. The remaining error is recorded on a compass correction card.
Compass Systems: Magnetic Compass Induced Errors, Deviation
What is the sequence for correcting variation and deviation errors?
- Magnetic Course = True Course ± Variation.
- Compass Course = Magnetic Course ± Deviation.
Compass Systems: Magnetic Compass Induced Errors, Deviation
Example of correcting for deviation and variation:
- True Course: 180°
- Variation: +10° (West) → Magnetic Course = 190°
- Deviation: –2° (from correction card) → Compass Course = 188°
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What is the Earth’s magnetic dip angle?
The angle created by the vertical pull of the Earth’s magnetic field in relation to the Earth’s surface, increasing as you move toward the magnetic poles.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Where is the Earth’s magnetic field parallel to the surface?
At the Magnetic Equator, halfway between the Magnetic North and South Poles.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Why doesn’t the compass needle pivot freely in three dimensions?
To prevent the needle from pointing up or down with the dip angle, the compass is designed to rotate only in the horizontal plane by lowering the center of gravity below the pivot point.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What happens to a compass near the magnetic poles?
The horizontal component of the Earth’s magnetic field becomes too small to align the compass, making it unusable for navigation.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Why is dip angle not of navigational interest?
The compass is designed to work in the horizontal plane, eliminating the effects of the vertical component of the Earth’s magnetic field.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What errors are caused by the Earth’s magnetic dip?
Northerly and southerly turning errors.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What causes northerly turning errors in a magnetic compass?
The center of gravity of the float assembly is below the pivot point, and magnetic dip causes the float to swing in the same direction as the turn, leading to a false northerly turn indication.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How does magnetic dip affect compass readings during a northerly turn?
Magnetic dip causes the compass card to lead, indicating the turn prematurely.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How can pilots correct for northerly turning errors?
Stop the turn 15 degrees plus half the latitude before reaching the desired heading.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Provide an example of correcting for northerly turning error at 40° latitude.
Stop the turn 15 + (40 ÷ 2) = 35 degrees before the desired heading.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Where is the northerly turning error most amplified?
Near the magnetic poles due to the increased effects of magnetic dip.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What causes southerly turning errors in a magnetic compass?
The float assembly lags due to magnetic dip, leading to a false southerly turn indication.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How does magnetic dip affect compass readings during a southerly turn?
Magnetic dip causes the compass card to lag, indicating the turn later than it actually occurs.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How can pilots correct for southerly turning errors?
Allow the compass to pass the desired heading by 15 degrees plus half the latitude before stopping the turn.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Provide an example of correcting for southerly turning error at 30° latitude.
Stop the turn 15 + (30 ÷ 2) = 30 degrees after passing the desired heading.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
Where is the southerly turning error most amplified?
Near the magnetic poles due to the stronger effects of magnetic dip.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What is the mnemonic to remember Northern/Southerly turning errors?
UNOS
Undershoot North
Overshoot South
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What is the mnemonic to remember East/West acceleration errors?
ANDS
Acceleration North
Deceleration South
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What causes acceleration errors in a magnetic compass?
Magnetic dip and inertia from changes in airspeed, combined with the pendulous mounting of the compass.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How does the compass behave when accelerating on an easterly or westerly heading?
The compass shows a false turn toward north.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
How does the compass behave when decelerating on an easterly or westerly heading?
The compass shows a false turn toward south.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
What mnemonic helps remember magnetic compass acceleration error?
“ANDS”: Acceleration-North, Deceleration-South.
Compass Systems: Magnetic Compass Induced Errors, Dip Errors
On which headings is acceleration error most noticeable?
Easterly and westerly headings.
Compass Systems: Magnetic Compass Induced Errors, Oscillation Error
What is oscillation error in a magnetic compass?
A combination of all compass errors, causing fluctuations of the compass card relative to the actual heading.
Compass Systems: Magnetic Compass Induced Errors, Oscillation Error
How can a pilot manage oscillation error when setting the gyroscopic heading indicator?
Use the average indication between the swings.
Compass Systems: The Vertical Card Magnetic Compass
What is the primary advantage of the vertical card magnetic compass?
It eliminates some of the errors and confusion associated with standard magnetic compasses.
Compass Systems: The Vertical Card Magnetic Compass
How is the dial of the vertical card magnetic compass graduated?
It uses letters for cardinal directions, numbers every 30°, and tick marks every 5°.
Compass Systems: The Vertical Card Magnetic Compass
What does the nose of the symbolic aircraft on the vertical card magnetic compass represent?
The lubber line, used to read the aircraft’s heading.
Compass Systems: The Vertical Card Magnetic Compass
What happens to the compass during a turn from a northerly heading?
The compass lags behind the turn.
Compass Systems: The Vertical Card Magnetic Compass
What happens to the compass during a turn from a northerly heading?
The compass leads the turn.
Compass Systems: The Vertical Card Magnetic Compass
What is eddy current damping in a vertical card magnetic compass?
Eddy currents are created by the oscillating magnet, producing a magnetic flux that opposes the oscillations, reducing their amplitude.
Compass Systems: The Vertical Card Magnetic Compass
What is the purpose of the Outside Air Temperature (OAT) gauge?
It measures the outside air temperature, providing useful information such as the temperature lapse rate with altitude changes.
Compass Systems: The Vertical Card Magnetic Compass
How does the OAT gauge measure temperature?
Using a bimetallic-type thermometer, where two dissimilar materials are welded together and twisted into a helix.
Compass Systems: The Vertical Card Magnetic Compass
Where is the sensing element of the OAT gauge located?
It is mounted to ensure it is exposed to the outside air.
Compass Systems: The Vertical Card Magnetic Compass
How is the OAT gauge calibrated?
It is calibrated in degrees Celsius (°C), Fahrenheit (°F), or both.
Compass Systems: The Vertical Card Magnetic Compass
What information can the OAT gauge provide to a pilot?
It helps determine the temperature lapse rate as altitude changes.
