When Shanell Mouland boarded a Philadelphia-bound plane out of Orlando early this month with her family, she was bracing for the worst.

Mouland was headed home to New Brunswick, Canada, Jan. 5 with her husband and daughters Grace, 5, and Kate, 3, who has autism and doesn't like to sit for long. They were returning from a week spent at Walt Disney World.

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

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

Instead of ignoring Kate, Kunkel put down his work and spent 2.5 hours during the flight playing games with the preschooler, calming her and keeping her busy with pictures of his puppies.

The simple act of kindness brought such extraordinary relief to Mouland that 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."

RELATED: Autistic, nonverbal teen told not to use iPad during flight takeoff.

Mouland's blog entry became a global 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. "It makes me feel good."

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