Operational Considerations
The FAA's policy letter Guidance for Polar Operations (March 5, 2001) outlines a number of special requirements for polar flight, which includes two cold-weather suits, special communication capability, designation of arctic diversion airports and firm recovery plans for stranded passengers, and fuel freeze strategy and monitoring requirements
Jet fuel freeze temperatures range between -40 and -50 °C. These temperatures are frequently encountered at cruise altitude throughout the world with no effect since the fuel retains heat from lower elevations, but the intense cold and extended duration of polar flights may cause fuel temperature to approach its freezing point. Modern long-distance airliners are equipped to alert flight crew when fuel temperatures reach these levels. The crew must then change altitude, though in some cases due to the low stratosphere over polar regions and its inversion properties the air may actually be somewhat warmer at higher altitudes.
Read more about this topic: Polar Route