What does the "2,000-foot rule" indicate in VNAV operations?

The "2,000-foot rule" in VNAV operations refers to the practice of starting a descent from cruising altitude to ensure that the aircraft is at least 2,000 feet above the crossing altitude before initiating the descent. This rule is significant because it provides a standardized safety buffer that helps prevent terrain or obstacle conflicts and maintains safe vertical separation from other aircraft. By adhering to this rule, pilots can manage their descent more effectively, allowing for timely coordination with air traffic control while ensuring compliance with established aviation safety standards.

This focus on maintaining a 2,000-foot buffer aids in managing the rate of descent and ensuring that the approach and landing phases of flight are conducted smoothly and within prescribed altitude limits, which is crucial for maintaining safety in busy airspace environments.