"We knew that flights were difficult for her," Mouland said. "And we knew this was going to be a tough one."

A businessman, Eric Kunkel sat down next to them on the plane, and Kate immediately started reaching for him and calling him "Daddy."

Instead of ignoring Kate and giving Mouland the condescending looks the mother is use to, Kunkel put down his work and spent the entire 2.5 hour flight playing games with the preschooler, helping her stay calm and keeping her busy by showing pictures of his puppies.

The selfless gesture brought Mouland an extraordinary amount of relief. The surprised mother could not stop thinking about the man's simple act of kindness and several days later she penned a post titled, "Dear 'Daddy' in Seat 16C Flight 1850 From Philly" on her blog "Go Team Kate."

"You could have shifted uncomfortably in your seat," she wrote. "You could have given her that smile that I despise because it means 'Manage your child, please.' ... Thank you for entertaining Kate so much that she had her most successful plane right yet. And thank you for putting your papers away and playing turtles with our girl."

Mouland's blog entry became a worldwide sensation, getting more than 70,000 likes on Facebook. It took one day for the blog post to reach Kunkel, an IT executive and married father of one in Villas, N.J.

"I would have never expected this to happen and I didn't, so it's a little overwhelming at times," he said in an interview with ABC news. "It makes me feel good."

"Sometimes the simplest things are such a big deal," Mouland told ABC. "But it's a big deal for him to treat her like a little person."