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Lesson 12.3 – System and Instrument Failures
System and instrument failures are more common than complete engine failures. A private pilot must be able to recognize the failure, maintain control of the airplane, and safely conclude the flight. All procedures below are based on standard FAA guidance; always follow the specific emergency checklist in your aircraft’s Pilot’s Operating Handbook (POH).
Primary FAA Sources
Airplane Flying Handbook (FAA-H-8083-3)
Pilot’s Handbook of Aeronautical Knowledge (PHAK) (FAA-H-8083-25)
Aircraft Flight Manual / Pilot’s Operating Handbook (POH) emergency procedures
Aeronautical Information Manual (AIM)
Vacuum System Failure
Vacuum System Failure
Many light airplanes use a vacuum (or pressure) system to drive the attitude indicator and heading indicator.
Recognition:
Unusual or frozen attitude/heading indicators
Low vacuum/pressure indication (if equipped)
Action:
Maintain control using the remaining instruments (turn coordinator, altimeter, airspeed, magnetic compass).
Cover or ignore the failed gyro instruments to avoid confusion.
Land as soon as practicable, especially if weather is IMC or marginal.
Pitot-Static System Failures
Pitot-Static System Failures
Pitot blockage (usually affects airspeed indicator):
Airspeed may go to zero or remain fixed.
Fly known pitch + power settings for the desired performance.
Static blockage (affects airspeed, altimeter, and vertical speed):
Altitude and vertical speed may freeze.
Airspeed may read incorrectly.
Use alternate static source if available (on most training airplanes the alternate static source is inside the cabin).
FAA guidance: Always consult the POH for the correct alternate-static procedure and expected instrument errors.
Electrical Failure
Electrical Failure
Alternator/generator failure leads to battery-only operation.
Reduce electrical load to essential items (ignition is magneto-powered and independent on most light airplanes).
Expect eventual loss of radios, flaps, lights, and electrically driven instruments.
Plan to land before the battery is depleted.
Partial Panel / Instrument Failures
Partial Panel / Instrument Failures
When one or more primary instruments fail:
Rely on the remaining functional instruments.
Cross-check frequently.
Avoid abrupt control inputs.
If in IMC, declare an emergency and request assistance.
Key FAA Principles (from Airplane Flying Handbook & PHAK)
Key FAA Principles (from Airplane Flying Handbook & PHAK)
Aviate – Navigate – Communicate.
Maintain aircraft control first.
Use the POH emergency checklist.
Declare an emergency when safety of flight is affected.
Land as soon as practicable when systems required for safe flight are lost.
Key Points
Key Points
Vacuum failure: fly partial panel and land as soon as practicable.
Pitot-static failure: use alternate static source if available; fly known pitch and power.
Electrical failure: reduce load and land before battery depletion.
Always follow the specific procedures in your aircraft’s POH.
Practice partial-panel control and emergency checklists regularly.
Links:
Intro to Aviation & Airplanes
Airfoils, Lift & Angle of Attack
Stalls, Critical Angle of Attack & Spin Awareness
Primary Flight Controls & the Three Axis
Stability, Controllability & Adverse Yaw
Engine Instruments & System Monitoring
Pilot Certification & Privileges
Medical Certificates & BasicMed
Flight Rules (Part 91 Highlights)
Airport Marking, Signs, & Lighting
Traffic Patterns & Airport Operations
Special Use Airspace & Other Airspace Areas
Airport Facility Directory & Chart Reading
The Atmosphere & Atmospheric Pressure
Airmasses, Fronts & Weather Patterns
Thunderstorms, Turbulence, Icing & Other Hazards
Weather Reports, Forecasts & Charts
Common Weak Areas & How to Fix Them
Private Pilot Privileges & Limitations
Lesson 11.2
Currency Requirements
Medical Certification & Basic Med After the Check ride
Continuing Education & Proficiency
Engine Failure & Forced Landings
In-Flight Fires & Electrical Problems
System and Instrument Failures
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