What action must pilots take close to their assigned altitude without ATC restrictions?

Pilots must maintain awareness of their altitude during the approach to their assigned altitude, particularly when there are no air traffic control (ATC) restrictions in place. This means they are expected to perform altitude adjustments as needed to ensure they reach their assigned altitude safely and accurately.

Choosing to both climb and descend at prescribed rates allows pilots to respond effectively to any discrepancies or altitude deviations. This capability is crucial for maintaining optimal vertical separation from other aircraft and for adhering to the standard procedures within controlled airspace. It enhances situational awareness and promotes a safe and orderly transition to the designated altitude.

In contrast to the other options, which either limit the pilots' actions or suggest inappropriate maneuvers (like climbing at the fastest rate or leveling off immediately), this approach of actively managing altitude changes aligns with best practices for safe aviation operations. Therefore, the necessity to adjust altitude—whether by climbing or descending—ensures that pilots can effectively reach their assigned levels in compliance with regulations and safety standards.