Originally Posted by Ditchdigger
(Yeah, I know that other than the number of syllables "fif-ty nine" and "U-nit-ed" don't sound very much alike, but Feith's explanation makes it seem as if the controller heard only the number "12".)
Actually, that's the first thing I thought.
"Fife-niner", with a bit of audio distraction in the background, could easily be mis-heard as "United". Mind-set follows.