Flight Plan Info
The Tropopause and Outside Air Temp (Static Air Temp) are used for many things, some of which are predicting turbulence, performance (fuel flow rates, airspeed) and planning for fuel temperature. The aircraft I fly has a minimum allowable fuel temperature of -40 degrees C. We are directed to avoid that by 3 degrees, meaning the lowest fuel temp I should see is -37 C. I have seen this once last year upon coasting in over Ireland. We climbed to get out of turbulence and found ourselves in -70 degree C air. Eventually we had to descend due to fuel temp.
The text below did not copy very well, but it shows info from a flight plan for today. The 13th note (dispatcher remarks) states the expected lowest fuel temperature for the route. Below that note are the winds aloft and temperatures for the planned and alternte flight levels. At 64N and 20W, the Tropopause is expected to be at 32,000 ft, and at 35,000 ft the Static Air Temperature is expected to be -50 degrees C. At 64N and 10W, the Trop is down to 28,000 ft, the 35,000 ft temp has warmed up to -42.
13 MINIMUM PREDICTED FUEL TEMPERATURE -21.3C AT ETE 0508
(64N020W - 64N010W) AS FLIGHT PLANNED
COMPUTED ENROUTE WINDS
FIX TROP CRZ FL TWO FLT LVLS LOWER TWO FLT LVLS HIGHER
SAT TAT SAT TAT SAT TAT SAT TAT SAT TAT
64N020W 32 35 32037 31 32052 33 32044 37 31031 39 29026
-50 -22 -51 -23 -51 -23 -47 -19 -45 -17
64N010W 28 35 25028 31 25023 33 25025 37 24031 39 24034
-42 -13 -43 -14 -43 -14 -41 -12 -41 -12