A force is a push or pull of an object in a interaction, a force is a vector. While in the air an aircraft has four main forces acting upon it: lift, thrust, weight and drag.
Lift is the force pushing the plane up into the air. Thrust is the force propelling the plane forward. The force of weight is the vector pulling the plane down toward Earth. Drag is the force caused by surrounding air pulling the plane backward.
Anonymous. "Forces of Flight | How Things Fly." Forces of Flight | How Things Fly. N.p., n.d. Web. 13 Dec. 2016.