LIFT | WEIGHT | THRUST | DRAG It is not necessary for pilots to have a super-precise understanding of the four forces. The concept of energy is considerably more important. In the cockpit (especially in critical situations like final approach) I think about the energy budget a lot, and think about forces hardly at all. Still, there are a few situations that can be usefully discussed in terms of forces, so we might as well learn the terminology.
The relative wind acting on the airplane produces a certain amount of force which is called (unsurprisingly) the total aerodynamic force. This force can be resolved into components, called lift and drag.
Total Aerodynamic Force = Lift + Drag
Here are the official, conventional definitions of the so-called four forces:
It is ironic that according to convention, the total aerodynamic force is not listed among the four forces.
The Four Forces — Low Speed Descent