A woman and her emotional support pig were asked to leave a US Airways flight - after the animal became disruptive.
The passenger and her pig were preparing to take off from Connecticut before the creature became unsettled, reports The Sun.
US Airways spokeswoman Laura Masvidal said the passenger was allowed to bring the pig on board as an "emotional support animal" under Department of Transportation guidelines.
However, she said, they were removed for being "disruptive".
The pig reportedly defecated in the aisle and, when his owner tied him to the armrest while she picked up the mess, it started letting out a loud howl.
Fellow passenger Roger Phelps snapped a picture of the woman leaving the flight with the large pig over her shoulder.
Speaking to CNN, Mr Phelps said: "She was talking to it like a person, saying it was being a jerk. I have no problems with babies, but this pig was letting out a howl."
He added: "I understand dogs and cats on planes. They come in crates, but this was way too big, and it had no container.
"It looked heavy. It was not a tiny, cute little pig."
Back in 2003, the Department of Transportation updated its policy regarding animals in air transportation to say that "animals that assist persons with disabilities by providing emotional support" qualify as service animals.
It's then up to the flight crew to determine whether an animal is a service animal.