In climb, thrust is required to overcome what combination?

• A. Weight component along the flight path
• B. Lift component along the flight path
• C. Normal force
• D. Side force

Answer: (A)

When climbing, gravity is split into a part that acts along the flight path and a part that acts perpendicular to it. The part that lies along the flight path pulls the airplane downhill and thus opposes forward motion up the path. Thrust has to overcome this weight component along the flight path (in addition to drag) to maintain the climb. Lift acts perpendicular to the path, so it doesn’t oppose motion along the climb direction, and the normal and side forces aren’t the forces that counteract thrust in the climb direction. So the key opposing factor thrust must overcome is the weight component along the flight path.