If the pitot tube and outside static vents become clogged, which instruments are primarily affected?

The primary instruments affected by a clogged pitot tube and outside static vents are the altimeter, vertical speed indicator, and airspeed indicator.

The pitot tube is responsible for measuring dynamic pressure, which is crucial for determining airspeed. When it becomes clogged, the airspeed indicator will either read zero or remain stuck at a specific value, failing to provide accurate airspeed information.

The static vent, on the other hand, provides ambient atmospheric pressure to several instruments that rely on this data to function correctly. When the static vents are clogged, the altimeter will not be able to obtain the proper external pressure, leading it to give erroneous altitude readings. Similarly, the vertical speed indicator also depends on the static pressure to determine the rate of climb or descent; if the static pressure is incorrect due to clogging, this instrument will not report accurately.

Understanding the specific roles of these instruments highlights why a blockage in the pitot tube and static vents directly impacts their performance, leading to potentially hazardous flight conditions due to failure to obtain accurate airspeed and altitude data. Other options presented involve instruments that either function independently of static pressure or rely on different sources of data, thus are not primarily affected by the mentioned blockages.