What should a pilot expect from their VSI when climbing with a blocked static port?

When a pilot experiences a blocked static port while climbing, the vertical speed indicator (VSI) can provide misleading information. The VSI functions by measuring changes in air pressure, which is influenced by the static pressure around the aircraft. If the static port becomes blocked, the VSI will not be able to respond accurately to the changes in altitude.

In the event of a climb, if the static port is blocked, the pressure inside the VSI will not reflect the decrease in atmospheric pressure that occurs with an increase in altitude. As a result, the VSI may indicate no vertical speed at all, leading to a reading of zero. This can be critically misleading for pilots who rely on VSI feedback to gauge their climb rate.

Understanding this characteristic is essential for pilots, as they need to recognize that with a blocked static port, the VSI may not provide reliable information, leading to potential misjudgements regarding the aircraft's performance in terms of climb or descent.