A couple got married on a plane so the bride's sick mum could attend.

As far as unusual weddings go, tying the knot mid-flight is pretty hard to beat.

US couple Kristy Stratton and Jim Larsen recently did just that. And the reason why is heartwarming.

Stratton, 41, has been a flight attendant for Alaska Airlines for more than 11 years, and she actually met her sweetheart during a stopover while traveling from Los Angeles to Seattle.

Sadly, Stratton's mum, Billie Jo Stratton, 70, was diagnosed with stage 4 lung cancer in 2014, and while she's determined to beat the illness, she's also made it her mission to see where her daughter works and attend her wedding.

Stratton told TODAY.com that she got the all-clear from the airline before arranging for her pastor to attend. She also asked fellow airline hostess and photographer Christina Frees, of Frees it in Time Photography, to capture her special day.

Passengers on board had no idea beforehand - but were quick to share the love with the happy couple.

"I was thinking of unique wedding ideas while driving home from a red-eye about a month before the wedding and thought it'd be a cool idea to get married on that exact flight," she said.

"My mum has been smiling for weeks — I love it. The wedding really lifted up her spirits and she even got to spend time with us in Seattle after, too.

"I was really touched and overwhelmed by the amount of love and joy flooding through the cabin. Not only did they make the day even more special for me, but for my mum as well."

Frees said it was the most unusual wedding she'd ever attended.

"It was really cool to see people coming together to celebrate total strangers," she said.

The couple held a proper wedding reception the day after and they plan to honeymoon in Iceland.

Have you ever attended an unusual wedding? Let us know below.