Buffeting experienced while cruising higher than normal at normal speed could be due to which condition?

• A. Either low speed or high speed buffet and difficult to identify
• B. Only low speed buffet
• C. Only high speed buffet
• D. Buffet cannot occur in this situation

Answer: (A)

Buffet is caused by unsteady airflow that separates from the wing and sheds vortices, creating vibration and roughness you feel in the controls. There are two main ways this happens: at low speed when the wing is near its stall angle of attack, the flow can separate and become turbulent (low-speed buffet); and at higher speeds near the aircraft’s Mach limit, compressibility effects cause shock waves and flow separation (high-speed buffet).

When you’re cruising at an altitude higher than usual but at a normal indicated speed, the true airspeed is higher and the Mach number you’re flying can creep toward the transonic range. That makes high-speed buffet a real possibility even though your indicated speed looks normal. It’s also possible to encounter low-speed buffet if the flight conditions (weight, AoA, gusts) push the wing toward stall margin.

Because buffet can arise from either mechanism and the same feel can result from different underlying causes, it can be difficult to identify which type is responsible just from sensation. So the explanation that covers both possibilities—either low-speed or high-speed buffet—is the most accurate for this scenario.