What is the minimum ambient temperature approved for takeoff?

What is the minimum ambient temperature approved for takeoff?

• A. -50C
• B. -40C (-40F)
• C. -60C
• D. -30C

Answer: (B)

Ambient temperature limits are part of an aircraft’s certified operating envelope. For takeoff, the airplane must be able to start engines and operate reliably at or above the lowest approved outside air temperature. For the CRJ-550, that lower bound is -40C, which also happens to be -40F. This boundary is set because below it the performance and reliability of critical systems (engine start, electrical, hydraulics, fuel, and anti-ice) aren’t guaranteed by certification. So temperatures colder than -40C aren’t approved for takeoff, while warmer temperatures are permissible. The -30C option is warmer than the minimum, but does not define the limit; the colder options would be below the certified minimum.

Ambient temperature limits are part of an aircraft’s certified operating envelope. For takeoff, the airplane must be able to start engines and operate reliably at or above the lowest approved outside air temperature. For the CRJ-550, that lower bound is -40C, which also happens to be -40F. This boundary is set because below it the performance and reliability of critical systems (engine start, electrical, hydraulics, fuel, and anti-ice) aren’t guaranteed by certification. So temperatures colder than -40C aren’t approved for takeoff, while warmer temperatures are permissible. The -30C option is warmer than the minimum, but does not define the limit; the colder options would be below the certified minimum.