Plain English Meaning

A simple rule that tells pilots which altitude to fly based on the direction they are heading. Aircraft going roughly east fly at one set of altitudes, and aircraft going roughly west fly at a different set. This keeps planes coming from opposite directions from being at the same altitude.

Full Definition

A cruising altitude rule under VFR (and IFR in uncontrolled airspace) that assigns specific altitudes based on magnetic course. When flying above 3,000 feet AGL on a magnetic course of 0° through 179°, pilots use odd thousands plus 500 feet (e.g., 3,500; 5,500; 7,500). On a magnetic course of 180° through 359°, pilots use even thousands plus 500 feet (e.g., 4,500; 6,500; 8,500). The rule separates opposing traffic vertically by direction of flight.

Context Anchor

Seen when planning cross-country flights, choosing a cruise altitude, or altitude selection for .