Which factor is critical in performing a steep spiral effectively?

The critical factor in performing a steep spiral effectively is applying wind drift correction. When executing a steep spiral, it is essential to account for wind direction and speed because these can significantly influence the flight path and descent rate. By correcting for wind drift, the pilot ensures that the aircraft maintains the intended trajectory, remaining within the desired reference point on the ground.

In a steep spiral, the aircraft is often maneuvering close to stall speeds due to the increased bank angles and reduced airspeed associated with the maneuver. Therefore, effectively applying wind correction helps maintain energy management and prevents unnecessary altitude loss that could compromise the maneuver's safety and control.

Other factors, such as maintaining a specific bank angle or flying below a listed airspeed, do not address the immediate need for maintaining course in the presence of wind. Altitude adjustments, while a part of many maneuvers, are not the primary concern during a steep spiral since the goal is to maintain control and accomplish the maneuver with precision.