A six-year-old boy flew alone to the wrong US city after he was incorrectly boarded on a Spirit Airlines plane.

Casper was travelling from Philadelphia to meet his grandmother in Fort Myers, Florida.

But he ended up in Orlando “ a four-hour drive from Fort Myers “ after he was mistakenly put on the wrong plane.

Spirit Airlines has apologised and offered to reimburse his grandmother for the drive to pick Casper up.

Casper was meant to be travelling from Philadelphia International Airport to Southwest Florida International Airport in Fort Myers on Thursday, to meet his grandmother, Maria Ramos.

But in a scene reminiscent of the film Home Alone 2, when Kevin gets on a wrong flight “ leaving him stranded far away from his family at Christmas, Casper was put on a plane to Orlando, which is 160 miles (260km) from Fort Myers.

After the plane he was supposed to be on landed and her grandson wasnt on it, panic set in for Ms Ramos.

I ran inside the plane to the flight attendant and I asked her, ˜Wheres my grandson? He was handed over to you at Philadelphia? Ms Ramos told WINK-TV, a television station in Fort Myers.

She said the flight attendant told her: No, I had no kids with me.

Fortunately, Casper managed to phone his grandmother soon after he landed in Orlando. Ms Ramos then drove from Fort Myers to pick up her grandson.

I want them to call me [and] let me know how my grandson ended up in Orlando, Ms Ramos said.

How did that happen? Did they get him off the plane? He jumped in the wrong plane by himself?

Spirit Airlines has apologised and said in a statement: We take the safety and responsibility of transporting all of our guests seriously and are conducting an internal investigation. We apologize to the family for this experience.

Such mishaps are uncommon, but unaccompanied minors as well as other passengers have travelled on wrong flights in the past.

In 2009, two different unaccompanied girls were placed on wrong Continental Airlines flights within the US. The airline blamed miscommunication among staff.

And in 2019, a boy was put on a United Airlines flight to Germany when he was supposed to be travelling to Sweden. (BBC)