bookworm,
Nah, you didn't. Until the first US aircraft flies on a planet where the acceleration of free fall is significantly different to 9.8 m/s^2, mass in aviation will be measured in
pounds.
Please remember, I said "tongue-in-cheek".
But if we're really getting technical, and depending on which gravitational decay with altitude formula that you accept, a fully loaded Boeing 747SP at 670,000 "pounds" MGTOW will weigh less at 41,000 feet than it does at sea level - by an astonishing amount equal to at least a fully loaded Cessna 182.
Not trying to start a "weight" vs. "mass" war here, but the latter is technically more correct than the former.
(Disregard fuel burn of course).
Bests,
Tom