What happens to the airspeed indicator if the static port gets blocked?

When the static port becomes blocked, the airspeed indicator and its associated readings are influenced by the changes in altitude and atmospheric pressure. In a situation where the static port is blocked, the airspeed indicator will not receive accurate static pressure readings from the atmosphere, leading to two different behaviors depending on whether the aircraft is climbing or descending.

During a climb, the aircraft is moving into thinner air, which normally would cause the airspeed to decrease. However, because the static port is blocked, the pressure in the static system does not decrease as it should with altitude gain. This makes the airspeed indicator display a lower speed than what is actually occurring - hence, the under-reading in climb.

Conversely, during a descent, the aircraft is moving back into denser air, which would typically cause an increase in actual airspeed. Yet, since the static system remains trapped at the previous altitude's pressure, the airspeed indicator will display a higher reading than reality, leading to an over-read in descent.

This behavior effectively captures how the static pressure plays a critical role in the functioning of the airspeed indicator, and highlights the need for accurate static pressure readings to ensure correct airspeed indications across varying altitudes. Understanding these principles is crucial for pilots to interpret