Maximum ambient temperature for takeoff and landing?

• A. ISA +25°C
• B. ISA +35°C / max 51°C
• C. ISA +40°C
• D. ISA +30°C / max of 45°C

Answer: (B)

Ambient temperature limits for takeoff and landing come from what the aircraft has been certified to handle. Performance data, engine thrust, aerodynamics, tires, hydraulics, and avionics are all validated within a certain range of temperatures. When the air is hotter, air density drops, which reduces engine thrust and wing lift, making takeoff and landing harder. To keep operations within tested and safe conditions, many aircraft specify an allowable deviation from ISA with an absolute temperature cap. The correct limit is ISA plus 35°C, with an absolute maximum of 51°C. That means you can operate at temperatures up to 51°C as long as the ISA deviation does not exceed +35°C. The other options propose limits that are either too low or exceed common certification envelopes, which would require new performance data or would be unsafe to rely on.