What is the absolute maximum ambient temperature for takeoff and landing?

• A. 46°C
• B. 51°C
• C. 55°C
• D. 60°C

Answer: (B)

High ambient temperatures reduce air density, which lowers lift for a given speed and also decreases engine thrust. For takeoff and landing, the aircraft must meet strict performance requirements (enough climb after takeoff and acceptable stopping distance on landing). The performance data are certified for a specific range of outside air temperatures, and there is an absolute limit beyond which those guarantees can no longer be made. That limit is 51°C. Above this temperature, the published takeoff and landing performance can’t be relied on, so operations are not permitted. Cooler temperatures improve density and margins, making safe takeoff and landing more achievable; hotter temperatures tighten margins and require longer runways or higher risk, which is why 51°C is set as the maximum.