B747-400 CAPTAIN FEELS INTERNATIONAL FLT DISPATCHED OVER POLAR ROUTE WITH FORECAST LOW TEMPERATURES FAILED TO CONSIDER LACK OF DATA REGARDING FUEL FREEZING LEVELS.

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RTE OFFERED BY DISPATCH IS POLAR WITH ENRTE TEMP BELOW -65 DEGS OAT AT THEIR PLANNED ALTS. PLANE ARRIVED WITH JET A FUEL NOT TESTED FOR FREEZING TEMP. JET A1 LOADED ZZZZ. NOW WE HAVE A MIXED LOAD OF JET A AND A1; NEITHER TESTED FOR FREEZING TEMP AS ZZZZ DOES NO FUEL TESTING FOR FREEZING TEMP. CREW HAS NO AWARENESS OF LIKELY FREEZING TEMP OF THIS MIX. DISPATCH SAYS LOWEST PREDICTED FUEL TEMP IS -38 DEGS; BELOW AFM LIMITATION; BUT OFFER NO EXPLANATION OF HOW THIS COULD BE CALCULATED GIVEN NO FUEL TESTING AND A MIXED A AND A1 LOAD. TANK #1 AND #4 PARTICULARLY OF CONCERN AS PERCENTAGE OF A IN THESE TANKS IS HIGHEST AND IT IS A LONG TIME BEFORE WE USE THIS FUEL. FUEL TEMP GAUGE NOT IN THOSE TANKS. ASK FOR NEW FLT PLAN TO FLY UNDER COLD TEMPS AND AT HIGHER MACH. ENCOUNTER OAT 8-10 DEGS BELOW FORECAST WIND/TEMP CHARTS AND WIND/TEMP ACARS UPLOAD. NOTIFY DISPATCH NUMEROUS TIMES. STAY LOW AT FL29.9 AND 29.0 UNTIL PAST COLD AIR. -35 FUEL TEMP COLDEST; 2 DEGS WARMER THAN WARN LIGHT AND AFM LIMITATION IF NO FUEL TEMP TESTING PERFORMED. PROCESS FAULTY WITH MIXED A AND A1 LOAD AND NO FUEL TESTING OUT OF USA. FLT PLAN FAULTY TRYING TO GET ONE TO FLY THROUGH COLD TEMPS WITH UNKNOWN FREEZING TEMPS FOR FUEL. BOEING POLAR OPS MANUAL REQUIRES 3 LEGS OF FUEL FREEZING TESTS BEFORE POLAR LEG FUEL TEST UNDER CONDITIONS OF -65 DEGS OAT DUE TO RESIDUAL FUEL FROM PREVIOUS LEGS STILL IN TANKS; BUT NOT ACR. PLTS DENIED ACCESS TO PREDICTED FUEL TEMP DATA AND DATABASE/ASSUMPTIONS THAT MAKE UP THIS 'DISPATCH DECISION' THAT THINGS ARE OK. MIXED LOADS OF A AND A1 OFFER MORE PERIL AS NOBODY KNOWS WHAT THE FREEZING TEMP WILL BE UNTIL FLAMEOUT. I HAVE HAD 2 INCIDENTS OF FUEL FREEZING CAUSING BOTH ENGS IN 2-ENG BUSINESS JETS TO QUIT IN ONE CASE AND RUN ONLY AT NEAR IDLE POWER. IT CAN HAPPEN.