When software executive Mike Alden boarded a flight from Boston to San Francisco last year, he was startled to see a parrot perched on top of another passenger's head.
The passenger insisted the parrot was a service animal that eased his anxiety about flying.
"He needed the parrot to keep him sane," said Alden, CEO of Axceler, which sells data-management software for corporations.
The odd things that passengers have brought on board are legendary: crocodiles, a tiger cub, even dead relatives (because it's cheaper to buy them a seat than putting them in cargo). Those instances clearly broke the rules.
But what about the bird?
Even though the pilot came out and insisted he wouldn't fly with the animal loose in the cabin, the parrot ended up staying, Alden said. Turns out, you can bring lots of different kinds of service animals onto a plane. A passenger simply needs to prove that the animal is not merely a pet. The animals must also not pose a safety risk or disruption to cabin service.
Other animals allowed, according to the Department of Transportation: Miniature horses, monkeys and pot-bellied pigs.
So the next time you hear squealing, don't assume it's that baby behind you.