← All explained questions · Supplemental · II — Preflight Procedures
During preflight, a pilot finds the static port partially obstructed by a wasp nest. If undiscovered and the pilot departs, which instruments will be affected?
Choices
Only the airspeed indicator.
Altimeter and VSI also rely on static source.
✓ Airspeed, altimeter, and vertical speed indicator.correct
all three pitot-static instruments rely on the static source). All three pitot-static instruments (airspeed, altimeter, VSI) use the static port for ambient pressure. A blocked static port causes: altimeter freezes at the altitude where it became blocked; VSI reads zero; airspeed indicator under-reads in climbs and over-reads in descents (because it uses the trapped static as reference for differential pressure with pitot).
Attitude indicator and heading indicator.
Attitude/heading indicators are gyroscopic, not pitot-static.
No instruments — only autopilot would be affected.
Three primary flight instruments are affected; this is critical.
Why
all three pitot-static instruments rely on the static source). All three pitot-static instruments (airspeed, altimeter, VSI) use the static port for ambient pressure. A blocked static port causes: altimeter freezes at the altitude where it became blocked; VSI reads zero; airspeed indicator under-reads in climbs and over-reads in descents (because it uses the trapped static as reference for differential pressure with pitot).
FAA source: FAA-H-8083-25C, PHAK Ch. 8, Pitot-static flight instrumentsbrowse the reference library →
Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question.