Definition
An autopilot vertical mode used to climb or descend the aircraft from one assigned altitude to another. In LVL CHG mode, the autopilot holds a pilot-selected airspeed by pitching the aircraft up or down, while the autothrottle (or pilot) sets a climb or descent thrust. The aircraft levels off automatically when it reaches the altitude pre-selected in the altitude window.
Plain English
A button on the autopilot that tells the airplane: 'Climb or descend to the new altitude I've dialed in, and keep my chosen speed while you do it.' When you reach the new altitude, the autopilot levels you off on its own.
Context Anchor
Seen on the autopilot or flight director mode display during climbs, descents, and altitude changes in instrument flying.
Why Pilots Care
Reduces pilot workload by automating the climb or descent while keeping speed stable and safe.
Intuition Check
Level change does not mean leveling the wings or leveling off. Here, it means changing from one altitude level to another while using pitch to protect the selected speed.
Example Sentence 1
After being cleared from 10,000 to 16,000 feet, the captain set 16,000 in the altitude window, pushed LVL CHG, and the autopilot pitched up to hold climb speed.
Example Sentence 2
During descent, selecting LVL CHG let the airplane maintain the target speed all the way down to the cleared altitude.