The first half of the equation of flight has to do with three factors: lift, force and gravity. To dive into these factors, we need to look into the physics of airplane flight and Newton’s Third Law of Motion: for every action, there is an equal and opposite reaction. The main key here is balance. To achieve flight we must first create forward thrust and lift to generate air pressure beneath the wings that will, in turn, lift the plane. This lift must create an imbalance where there is more lift or force upward than there is gravity pushing downward. Airplane wings are shaped with an angle of attack that maximises the amount of air hitting the bottom of the wing. Too much tilt and the airflow around the wings becomes too choppy and irregular and a plane fails to sustain lift and fly correctly. A 15 degree tilt tends to be the maximum sustainable angle for aerodynamic flight.