I had the same problem as Kevin on my FIRST flight up north a few years ago. Damn cold with no heat at 10,000' in December!!! It was an improperly connected duct, and an unpleased spousal unit and toddler contingency - if you hear what I'm saying.
Since then, I've not had any problems, and always fly with blankets and a space heater as back ups - but have not used them in necessity . . . .
I believe the true experts on this should be, at a minimum, Larry and Gerry.
Gents? Any problems or suggestions?
Keven
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RHODE ISLAND MEDICAL MARIJUANA DISPENSARY