Which statement is true about straight-and-level flight balance?

• A. Lift equals Weight and Thrust equals Drag
• B. Opposite forces are equal
• C. Lift equals Drag and Weight equals Thrust
• D. There is no net force

Answer: (A)

In straight-and-level flight the aircraft isn’t accelerating up, down, or along its path, so forces balance in both directions. The lift from the wings must exactly counteract the weight pulling downward, and the thrust from the engines must exactly counteract the drag resisting forward motion. When Lift equals Weight and Thrust equals Drag, the net force is zero and the aircraft maintains constant altitude and airspeed. This precise pairing is what makes the statement true. The other ideas are less specific or incomplete: simply saying opposite forces are equal is vague, lift equaling drag with weight equaling thrust mixes the directions, and while there is no net force, that alone doesn’t specify which forces balance to keep the flight in level, steady condition.