Instrument Rating – Aeroplane (INRAT) Practice Exam 2025 - Free Instrument Rating Practice Questions and Study Guide

When discussing the implications of Pitot tube blockage, it is essential to understand the performance of the airspeed indicator and the term PORC. This acronym stands for "Pitot Over-Reads in Climb."

In the event of a blockage in the Pitot tube, particularly if the aircraft is climbing, the airspeed indicator will indicate an airspeed that is higher than the actual true airspeed. This phenomenon occurs because the static pressure is not being sensed correctly, leading the airspeed indicator to display a higher reading due to the decrease in ambient pressure associated with altitude gain.

Understanding that PORC describes a condition where the airspeed indicator incorrectly shows a greater airspeed during climbing conditions is crucial for pilots. It helps in correctly diagnosing the situation and taking appropriate corrective actions. This knowledge aids in ensuring flight safety and the proper management of the aircraft's performance in potentially confusing scenarios.