Which operations are defined as 'critical phases of flight' for crew members?

The classification of critical phases of flight encompasses all operations below 10,000 feet, which includes various activities such as takeoff, landing, and the entire taxi phase. This definition is grounded in the fact that these phases are associated with significant changes in aircraft performance and increased pilot workload, which can elevate the risk of errors.

During these phases, the aircraft is closer to the ground, and pilots are more directly engaged with climate factors, potential obstacles, and other air traffic. Furthermore, being vigilant during these operations is crucial for maintaining safety. It is important for crew members to focus on managing the aircraft appropriately during this heightened risk surface area, thus making this the most comprehensive and correct definition of critical phases of flight.

While the other options mention operations that might occur during critical phases, they fail to encompass the full scope of what is considered critical when flight operations are under 10,000 feet. Such operations also include the complexities involved in taxiing and the transition phases of ascent and descent, reinforcing the correct understanding of critical phases as defined.