A320 Family Temperature Limitations
All,
The A320 family minimum temperature limitations vary according to altitude.
The -70c limit mentioned above is at the maximum certified altitude. The minimum allowable outside air temperature increases (gets warmer) with a decrease in altitude. For example, an early model A320 at 20000 feet has a minimum outside air temperature limitation of -55c. An A321 at 20000 feet has a limit of -60c. A look in the environmental section of your limitations chapter will show you the appropriate graph for your aircraft model.
I am not sure why the limitation is in effect, but the fact that the aircraft manufacturer states it as a limit is good enough for me. :-))
best regards,
Bruce Waddington