When is it appropriate for a pilot to enter a holding pattern?

A pilot is instructed to enter a holding pattern primarily when directed by air traffic control, which is responsible for managing air traffic and ensuring safe separation between aircraft. Holding patterns are used to manage traffic flow at busy airports, to allow for other aircraft to land or to wait for weather conditions to improve before continuing to land.

When air traffic control instructs a pilot to enter a holding pattern, it indicates an immediate need for the aircraft to remain in a designated area until further communication or instructions are given. This helps in maintaining organized and safe air traffic management.

In contrast, entering a holding pattern solely based on the situation described in the other options can lead to confusion and potential safety issues. For instance, entering a holding pattern while on final approach or while waiting for landing instructions might disrupt the flow of other aircraft. Additionally, personal considerations like pilot fatigue should be addressed through proper crew management protocols rather than through holding patterns.