* If lift is greater than the force of gravity, the airplane will accelerate upwards, causing it to climb.

* In contrast, if lift is less than the force of gravity, the aircraft will decelerate upwards, causing it to descend.

* Lift equals the force of gravity when an aircraft is flying at a constant altitude and speed. This condition is known as equilibrium or steady-state flight.

Lift and gravity act in opposite directions, and the sum of these two forces determines the rate of climb or descent of an airplane.