Private Pilot Private Exam

If both the pitot tube and outside static vents become clogged, which instruments would be affected?

1. Only the altimeter

2. Airspeed indicator and altimeter

3. Airspeed, altimeter, and vertical speed indicator

4. All flight instruments

The correct answer is: Airspeed, altimeter, and vertical speed indicator

When both the pitot tube and the outside static vents become clogged, it impacts several flight instruments that rely on these systems to function correctly. The pitot tube is primarily responsible for measuring the dynamic pressure of the air, which is used by the airspeed indicator to determine the aircraft's speed through the air. If the pitot tube is blocked, the airspeed indicator will not provide an accurate reading and can either freeze or display an erroneous speed based on existing pressures at the time of blockage. On the other hand, the static vents are crucial for the altimeter and the vertical speed indicator, which depend on static pressure to measure altitude and rate of climb or descent, respectively. If the static vents are blocked, these instruments will also fail to reflect the true altitude or rate of climb, as they will no longer receive accurate static pressure information. Thus, with both the pitot tube and static vents clogged, all three instruments—the airspeed indicator, altimeter, and vertical speed indicator—will be affected, making the answer comprehensive in identifying the impact on critical flight instruments.