Leah Hope

CHICAGO (WLS/CNN) -- A group of children battling cancer, along with their families, went to the North Pole to visit Santa. Well, the fantasy version of the North Pole.

The 34 children undergoing cancer treatment took off from O'Hare International Airport -- along with real United Airlines pilots and flight attendants - as part of the annual Operation North Pole event which aims to put some well-deserved smiles on their faces.

The quick trip may have given the older kids a clue, but for those who "believe," they got to see Santa Claus.

"I'm pretty excited about this," said Tait Wasser, a United Airlines pilot who volunteered for the assignment.

"It's really exciting and really cool," said Ava Lee, who was joined by her mother Esther Lee.

"They include the whole family and all the siblings. We are so thankful and really enjoying this time together," Esther Lee said.

When they arrived at the "North Pole," Santa greeted them and they were treated to activities, gifts and time with comfort dogs.

"It's just amazing that we can see Samantha smiling and doing this stuff," said Mariusz Karas, father of Samantha Karas.

Cal's Angels partnered with United to find these special passengers. The organization's president understands what the families are going through after the passing of her step-son.

"They leave with so many material things, but the things that are really going to last are the memories that they will build as an entire family," said Stacey Sutter, of Cal's Angels.

TM & © 2016 Cable News Network, Inc., a Time Warner Company. All rights reserved.