What altitude range must pilots monitor closely during climb or descent to prevent deviations?

Pilots must closely monitor their altitude within 1,000 feet of their assigned altitude during climb or descent to ensure adherence to air traffic control (ATC) instructions and maintain safe separation from other aircraft. This critical altitude range allows pilots to quickly identify and correct any deviations, ensuring they reach their intended altitude efficiently and safely. Monitoring within this range also helps prevent altitude encroachments that could lead to conflicts with other aircraft, as ATC commonly provides vertical separation based on this standard. The focus on 1,000 feet is part of best practices in aviation safety, facilitating effective communication with ATC and ensuring compliance with airspace regulations.