Turbulence penetration speed is defined as the lower of 280 KIAS or Mach 0.75, whichever is lower.

• A. Higher of 280 KIAS or Mach 0.75
• B. Lower of 280 KIAS or Mach 0.75
• C. Always 250 KIAS
• D. Depends on weight

Answer: (B)

Two speed limits are in play: a fixed indicated airspeed limit (280 KIAS) and a Mach limit (0.75). The turbulence penetration speed is the smaller of these two values, so you stay under both limits at all times. This ensures you don’t exceed the IAS limit at lower altitudes or the Mach limit at higher altitudes, which protects both structural integrity and aerodynamic performance in turbulence. Depending on altitude, the controlling value will shift, but the rule remains: fly at the lower of 280 KIAS or Mach 0.75. The other options don’t reflect this dual-limit rule, and weight does not determine turbulence penetration speed.