Plain English Meaning

When an aircraft climbs, the same four forces are at work as in level flight, but they balance differently. Climbing is not done by lift pulling the airplane up — it is done by the engine producing more thrust than is needed to overcome drag. That extra thrust is what carries the aircraft uphill. In a steady climb, lift and weight are still about equal; it is the surplus thrust that buys the altitude.

Full Definition

The set of aerodynamic and mechanical forces — lift, weight, thrust, and drag — acting on an aircraft as it transitions from level flight into a climb and during steady-state climb. When climb is initiated, the wing's angle of attack momentarily increases to produce excess lift, but once a steady climb is , lift is again roughly equal to weight. The defining feature of a steady climb is that thrust must exceed drag by an amount sufficient to support a component of the aircraft's weight that now acts rearward along the . therefore depends on (or ) beyond what is needed to level flight at that .