What is the Turbulent Air Penetration Speed?

What is the Turbulent Air Penetration Speed?

• A. 225 knots
• B. 235 knots
• C. 235/0.75
• D. 290 knots

Answer: (C)

Turbulent air penetration speed is the speed you hold through turbulence to keep gust loads within safe limits. It’s not a single fixed value; it’s defined by two constraints: an indicated-airspeed cap and a Mach cap. The notation 235/0.75 expresses both limits—keep the speed at or below 235 knots indicated, or at or below Mach 0.75, whichever yields the lower airspeed in the current conditions. This dual limit is used because at different altitudes the same Mach number corresponds to different IAS, and you want to ensure you don’t exceed structural or buffet limits in turbulence. The other numbers don’t reflect this two-part restriction, which is why the dual form is the correct way to represent the Turbulent Air Penetration Speed.

Turbulent air penetration speed is the speed you hold through turbulence to keep gust loads within safe limits. It’s not a single fixed value; it’s defined by two constraints: an indicated-airspeed cap and a Mach cap. The notation 235/0.75 expresses both limits—keep the speed at or below 235 knots indicated, or at or below Mach 0.75, whichever yields the lower airspeed in the current conditions. This dual limit is used because at different altitudes the same Mach number corresponds to different IAS, and you want to ensure you don’t exceed structural or buffet limits in turbulence. The other numbers don’t reflect this two-part restriction, which is why the dual form is the correct way to represent the Turbulent Air Penetration Speed.