The ambient air temperature limitation for landings is:

• A. -50 °C to ISA +25 °C
• B. -20 °C to ISA +40 °C
• C. -40 °C to ISA +35 °C
• D. 0 °C to ISA +20 °C

Answer: (C)

Landing procedures and the performance data used for them are certified within a specific ambient temperature envelope. For the Beechjet 400A, the approved range is -40 °C to ISA plus 35 °C. This range keeps the aircraft’s systems, fluids, and materials operating within the conditions tested during certification, so the performance numbers (like landing distances and handling characteristics) remain valid.

The low end, -40 °C, is set to ensure things like fuel freezing tendencies, hydraulic fluid viscosity, tire temperatures, and sensor reliability stay within known limits; going colder can push components outside their tested operating range. The high end, ISA +35 °C, ensures sufficient air density for predictable approach and landing performance and keeps environmental control and avionics systems functioning within their validated envelope. Outside these bounds, performance data and system behavior aren’t guaranteed.

Other ranges would either demand conditions that are outside the tested certification envelope or would not align with the tested limits for materials and systems, which is why the -40 °C to ISA +35 °C range is the correct one.