Flight Instruments Module 4: Altimeter and VSI

Altimeter and Vertical Speed Indicator (VSI) Errors

• Altimeter errors can be caused by malfunctioning equipment, misinterpretation by pilots, and blocked static systems.
• A blocked static system impairs the altimeter's ability to accurately measure altitude, leading to serious consequences.
• Techniques for identifying altimeter errors include:
  • Verifying the altimeter reads correct field elevation during pre-flight.
  • Comparing the altimeter reading with the expected altitude based on the flight plan and nearby waypoints or landmarks during flight.
• VSI errors can manifest as delayed or inaccurate rate of climb or descent readings.
• Regular calibration and cross-referencing with other climb-rate indicators can help detect VSI errors.
• Pilots can perform a static system leak check to ensure the VSI responds correctly to controlled changes in static pressure.

Gyroscopic Instrument Errors

• Gyroscopic instrument errors can occur due to power failures, gyro drift, or mechanical issues.
• Understanding the principles of gyroscopic precession and rigidity in space helps pilots anticipate and interpret the indications of these instruments correctly.
• Regular pre-flight checks of the vacuum or electrical systems that power gyroscopic instruments are essential for error prevention.
• Instruments susceptible to errors include:
  • Turn coordinator (powered by electricity or a vacuum system).
  • Heading indicator (immune to errors that affect magnetic compasses).
  • Attitude indicator (critical in maintaining proper pitch and bank angle).

Compass Errors

• Compass errors include variation, deviation, and dip errors.
• Variation is the difference between magnetic north and true north, requiring constant attention to update navigation plans correctly.
• Deviation arises from the magnetic fields created by the aircraft's electronic systems and structures.
• Dip error occurs due to the Earth's magnetic field lines, causing the compass to tilt toward the poles.
• Proper calibration and 'swinging the compass' (a method used on the ground to calibrate the compass and document deviations) are essential for minimizing compass errors.
• Pilots can learn to correct for these errors through practice and by using a compass correction card.

Altimeter and Vertical Speed Indicator (VSI) Errors

• Altimeter errors can occur due to malfunctioning equipment, misinterpretation by pilots, or a blocked static system, leading to inaccurate readings and posing a significant risk to flight safety.
• A blocked static system impairs the altimeter's ability to interpret changes in air pressure, leading to inaccurate readings.
• Techniques for identifying altimeter errors include:
  • Verifying the altimeter reading with correct field elevation during pre-flight checks.
  • Comparing the altimeter reading with expected altitude based on the flight plan and nearby waypoints or landmarks during flight.
• If an altimeter error is detected, the procedural steps to correct it include:
  • Coordinating with air traffic control.
  • Using GPS data as a cross-reference.
  • Recalibrating the altitude settings.

Vertical Speed Indicator (VSI) Errors

• VSI errors can occur due to static system issues, leading to inaccurate readings.
• Techniques for identifying VSI errors include:
  • Performing a pre-flight VSI check to ensure no pre-existing trend indication when on the ground.
  • Monitoring for uncommanded changes in readout during flight.
• If a VSI error is detected, the troubleshooting steps include:
  • Verifying if the issue affects the altimeter to determine if it's a static system issue.
  • Selecting the alternate static source, if equipped, and monitoring for changes in the VSI's behavior.
  • Communicating with flight controllers for altitude verification.

Gyroscopic Instrument and Compass Errors

• Gyroscopic instrument errors can occur due to power failures, gyro drift, or mechanical issues.
• Compass errors can occur due to variations, deviations, and dip errors.
• Variation is the difference between magnetic north and true north.
• Deviation arises from the magnetic fields created by the aircraft's electronic systems and structures.
• Dip error occurs due to the tilting of the Earth's magnetic field, particularly near the poles.
• Proper calibration of the compass is critical to minimize errors.

Error Management

• Routine checks and maintenance are essential to identify and correct instrument errors.
• Pilots should verify instrument readings with visual cues and other navigational checks when possible.
• Effective error management is crucial to ensure flight safety and precision in flight instrument readings.

Altimeter and Vertical Speed Indicator (VSI) Errors

• Altimeter errors can occur due to malfunctioning equipment, misinterpretation by pilots, or a blocked static system, leading to inaccurate readings and posing a significant risk to flight safety.
• A blocked static system impairs the altimeter's ability to interpret changes in air pressure, leading to inaccurate readings.
• Techniques for identifying altimeter errors include:
  • Verifying the altimeter reading with correct field elevation during pre-flight checks.
  • Comparing the altimeter reading with expected altitude based on the flight plan and nearby waypoints or landmarks during flight.
• If an altimeter error is detected, the procedural steps to correct it include:
  • Coordinating with air traffic control.
  • Using GPS data as a cross-reference.
  • Recalibrating the altitude settings.

Vertical Speed Indicator (VSI) Errors

• VSI errors can occur due to static system issues, leading to inaccurate readings.
• Techniques for identifying VSI errors include:
  • Performing a pre-flight VSI check to ensure no pre-existing trend indication when on the ground.
  • Monitoring for uncommanded changes in readout during flight.
• If a VSI error is detected, the troubleshooting steps include:
  • Verifying if the issue affects the altimeter to determine if it's a static system issue.
  • Selecting the alternate static source, if equipped, and monitoring for changes in the VSI's behavior.
  • Communicating with flight controllers for altitude verification.

Gyroscopic Instrument and Compass Errors

• Gyroscopic instrument errors can occur due to power failures, gyro drift, or mechanical issues.
• Compass errors can occur due to variations, deviations, and dip errors.
• Variation is the difference between magnetic north and true north.
• Deviation arises from the magnetic fields created by the aircraft's electronic systems and structures.
• Dip error occurs due to the tilting of the Earth's magnetic field, particularly near the poles.
• Proper calibration of the compass is critical to minimize errors.

Error Management

• Routine checks and maintenance are essential to identify and correct instrument errors.
• Pilots should verify instrument readings with visual cues and other navigational checks when possible.
• Effective error management is crucial to ensure flight safety and precision in flight instrument readings.

Learn about the altimeter and vertical speed indicator, and how to identify and manage errors in these flight safety instruments. Build on your knowledge of gyroscopic instruments and compass errors from the previous module.