Originally Posted by
Packrat
Even though LAS is in the desert it does get humid there, especially this time of year. Yesterday, for instance, the humidity was 45%. Unusual for a desert environment, but that's enough to form cold fuel frost.
Used to do evening departures from Mumbai, with turns from Dubai, Kuwait, Daman, Muscat (all waterside airports) During the winter, temps at out stations could range 15 and 20 degrees C, with light humid onshore breezes.
After a few hours at cruise the jet would cold soak. It was common to have ice on the upper surface of the wings. Per SOP... transfer cold wing fuel to the center tank then put warm fuel (from the bowser) into the wing. Ice turns to water, of course. However tactile checks were always accomplished I/A/W SOPs... with ladder and all and no mobile phone pictures. A back pack, which I referred to the Round-up weed killer pump, containing de-ice fluid would be used de-ice the upper surface of the wing.