Savannah Phillips was flying on United Airlines between Oklahoma and Illinois on Tuesday when she ended up being placed next to a horror seatmate.

In a Facebook post Savannah said the man, who appeared to be around 60 years old, fat-shamed her in a text message.

“His phone was maybe 12 inches (30cm) from my face and he proceeded to text someone that he was sitting next to ‘a smelly fatty’,” she said.

The words — which she said were displayed in huge font — brought her to tears.

“I was shocked and it was like confirmation of the negative things I think about myself on a daily basis,” the woman said.

“Before I knew it, I could feel hot, salty tears coming down my face. I sat and cried silently, hoping this guy didn’t try to make small talk, because I didn’t trust how I would react and I didn’t want to get kicked off the plane.

“I was so hurt ... I’m not the biggest person on the aeroplane, but I’m not the smallest. My worst nightmare is someone being uncomfortable because they have to sit next to me.”

Then came an announcement that the flight would be delayed, leaving her cringing and she continued to silently cry and scrunch herself up against the side of the plane as much as possible.

Ten minutes later, something incredible happened. A man sitting in the row behind them tapped the fat-shamer on the shoulder and asked to talk to him. He said they were going to switch seats because he knew the man was texting about Savannah and he was “not putting up with that”.

After switching with the man, her new seatmate saw her crying and “encouraged me not to let that guy get to me and that everything was going to be fine”.

“He said he just happened to see that guy’s text messages he started shaking he was so mad and knew he had to do something,” she said.

It turns out the passenger Savannah calls her “hero” is Chase Irwin, from Nashville.

“I told him that he was a blessing sent to me and how thankful I was that he was there ... he did prove to me today that (1) not only does God see me, but (2) there are more good people in the world than bad.”

Chase told News News Channel 5he just had to do something about the situation.

“I was going to wait until the end of the flight to say something but I could not have this guy sit next to her this whole flight and her thinking he’s making fun of her,” he said.

“It really gets to me deep down when I see someone crying, and when I saw her crying it really hit me hard and actually got sick to my stomach.”