What drives a climb
In a steady climb, the four forces are not balanced the way they are in level flight. Thrust exceeds drag, and this excess force has a component directed upward along the climb path — that component is what drives the aircraft upward.
A common misconception is that lift must exceed weight to climb. In a steady climb, lift and weight are nearly balanced (lift is actually slightly less than weight). It is the excess thrust acting along the flight path — not an excess of lift — that produces the climb.
Climb performance
| Rate of climb (Vy) | Maximum altitude gained per minute — the best-rate-of-climb speed |
| Angle of climb (Vx) | Maximum altitude gained per unit of horizontal distance — best angle speed, steeper but slower |
| Climb rate unit | Feet per minute (fpm) |
| Limiting factor | Excess thrust available above drag |
Zoom climb vs sustained climb: A zoom climb trades kinetic energy (airspeed) for potential energy (altitude) — the aircraft pitches steeply and climbs rapidly but decelerates. A sustained climb is steady-state; the aircraft climbs at constant airspeed, using ongoing excess thrust.
Related terms
- Level Flight — the balanced state a climb departs from
- Descent — the opposite state
- Thrust — excess thrust is what enables a climb
- Drag — the force thrust must overcome first