"I'm a new pilot and took a thermos of coffee up with me for the first time. I opened it at altitude and — you guessed it — sprayed hot coffee all over myself. Is there a trick to this or am I stuck drinking cold coffee in cruise." — Wiley P.
“A pilot friend of mine also liked to sip coffee in cruise. His solution was a child’s ‘sippie cup’ that would let the pressure out the valve and couldn’t spill on his upholstery.
Personally, I can’t bring myself to do the toddler act. But I also like a cup of hot coffee just before I descend to my destination. Here’s my secret.
When you fill your thermos before flight, fill it all the way to the top so that liquid spills out when you screw down the top. This prevents trapped air, which is what pressurizes the contents when you reach cruising altitude. The liquid is barely compressible, so can’t expand and spray out later. This works for any non-carbonated drinks in a thermos, hot or cold.
Of course, drinking too much coffee in cruise can create its own problems, but that’s a different discussion.”
Have you learned something about inflight refreshment in light airplanes … the hard way?
(If so, please share below.)