My son had a meltdown last time we flew, too.
To be fair, after waiting in the check-in line, security line, baggage-scan line (they scan your bags three times when you leave Hawaii) for about 3 hours while pregnant and needing to pee, I was about ready to have a meltdown. ("You and me both, kiddo.")
Flying is *hard* on kids. It's hard on adults. It is a LOT of sensory stimulation and waiting and standing in lines and dealing with crud and your parents being stressed... I can't blame the kid for freaking out. I probably would have, too, in his shoes.