How does the maximum operating airspeed (Vmo) change with altitude?

The maximum operating airspeed, known as Vmo, is the maximum speed at which an aircraft is certified to operate at a given altitude. As altitude increases, Vmo typically decreases due to the reduction in atmospheric pressure and density. This phenomenon is primarily influenced by the structural limitations of the aircraft and the associated aerodynamic forces.

At higher altitudes, the thinner air reduces the lift and drag forces acting on the aircraft, which makes it necessary to lower Vmo to avoid structural damage or excessive aerodynamic loads. Additionally, as the aircraft ascends, the engine performance can also be affected, which may limit the maximum safe airspeed. Understanding this relationship between altitude and Vmo is vital for pilots to ensure safe operation of the aircraft within its design limits.

Therefore, the correct answer is that Vmo decreases with altitude, ensuring that pilots maintain adequate control and structural integrity of the aircraft during flight.