An airline captain stepped up and wrote a letter to the tooth fairy after a 6-year-old girl lost one of her teeth during a United Airlines flight.

Lena and her family boarded a late-night flight from New York to their home state of South Carolina. The pair had endured a 36-hour delay in the Big Apple after they concluded their vacation in Norway, Lena’s mother, Lauren Larmon, told Fox News Digital.

Exhausted, Lena slept on the flight and hadn’t noticed she lost her bottom tooth until they disembarked and were heading to the baggage claim area at the Greenville-Spartanburg International Airport in Greer, South Carolina.

HERE'S HOW MUCH, ON AVERAGE, THE TOOTH FAIRY PAYS PER TOOTH 

Larmon said her husband Brian and their son James were with her and Lena when the startling discovery was made.

"We groggily picked Lena up and were walking down to grab our bag," Larmon recalled. "We sat her down, and she realized, ‘Oh, my gosh, my tooth fell out.’"

Lena Larmon shows missing tooth

Lena Larmon, 6, unknowingly lost her bottom tooth while she was on a United Airlines flight, her mother, Lauren Larmon, said. (Lauren Larmon)

"She started crying, saying, ‘I have nothing for the tooth fairy,’" Larmon continued. "You know, she's tired, she’s six."

The family attempted to go back to the plane, hoping they’d be able to retrieve Lena’s lost tooth, but the security doors were completely shut. It was also 2 a.m., so airport staff were few and far between, Larmon said.

HOW TO KEEP YOUR TEETH HEALTHY AND WHITE

Lena and Larmon did cross paths with the flight crew, who took care of them during their United Express flight, however.

"They saw Lena upset and asked what happened," Larmon recalled.

Captain Josh writes tooth fairy letter for Lena

Captain Josh wrote a letter to the tooth fairy for Lena, a young girl who lost her tooth during a United Express flight from New York to South Carolina. (Lauren Larmon)

"A flight attendant said, ‘You know, I think the tooth fairy will understand. It’s not a big deal. I’m sure she deals with this all the time,’" she continued. "But that didn’t quite do what I guess Lena needed it to do, and she was just really sad."

OKLAHOMA AIRPORT STAFF FIND A STUFFED DRAGON AND DOCUMENT ITS JOURNEY ONLINE 

Larmon said she told Lena they’d figure out a plan. That’s when Captain Josh Duchow stepped in to save the day.

He took out a piece of paper from his bag and wrote a letter on Lena’s behalf.

"Dear tooth fairy, Lena had a tooth fall out on her flight to Greenville, please take this note in place of her tooth," Duchow wrote.

Captain Josh's tooth fairy letter

Captain Josh's tooth fairy letter: "Dear tooth fairy, Lena had a tooth fall out on her flight to Greenville, please take this note in place of her tooth." (Lauren Larmon)

Larmon recalled that Lena asked if the letter would really work — and everyone reassured her it would.

CLICK HERE TO GET THE FOX NEWS APP

"Everyone should be this kind to kids," Larmon said. "Captain Josh just really went out of his way to make a bad situation much better."

Lena placed the letter and a shiny bead under her pillow when they arrived during the wee hours of June 18.

To Lena’s surprise, Captain Josh’s letter earned her a reply from the tooth fairy. 

Lena Larmon smiles

Lena Larmon's frown turned upside down after Captain Josh wrote a letter to the tooth fairy explaining that the girl lost her tooth on a plane. (Lauren Larmon)

Under her pillow was a note that said, "Lena, it's okay. I'll find your tooth. Keep brushing."

Fox News Digital reached out to United Airlines for a comment from [Captain Josh] Duchow. A spokesperson issued a statement on his behalf.

FOLLOW US ON FACEBOOK FOR MORE FOX LIFESTYLE NEWS

"At United, travel isn't about just getting customers from A to B, but creating memorable experiences that make customers excited to fly with us," the airline said in a statement. 

"We're proud to see moments like this that underscore our commitment to going above and beyond for our customers and creating an airline where Good Leads the Way."