What happens to the airspeed indicator in the case of static port blockage at a higher altitude?

When the static port becomes blocked, the airspeed indicator is affected due to the change in atmospheric pressure. At higher altitudes, the static pressure decreases, which is what the airspeed indicator uses to calculate airspeed. If the static port is blocked, the instrument cannot accurately measure the ambient static pressure, which leads to improper readings.

In the case of a blockage while climbing to higher altitudes, the airspeed indicator will be unable to correct for the decrease in static pressure. As a result, it will inaccurately portray a lower airspeed than true airspeed because it is still reading from the stale static pressure trapped behind the blockage. This outdated reading does not account for the changing atmospheric conditions, leading to the perception that the aircraft is moving slower than it actually is.

Thus, the airspeed indicator would show a lower than true airspeed in the case of a static port blockage at higher altitudes. Understanding this phenomenon is crucial for pilots, as it can significantly impact decision-making and flight safety.