The unaccompanied child landed in Orlando instead of Fort Myers in southwest Florida - to the horror of grandmother Maria Ramos who was waiting for him at Southwest Florida International Airport.

It was her grandson's first-ever flight as he boarded a Spirit Airlines flight from Philadelphia.

Ms Ramos received a call from her grandson from the airport in Orlando telling her that he had landed.

She explained how his luggage arrived at the Fort Myers airport but there was no sign of him, in an interview with ABC News.

Ms Ramos said: "They told me he's not on his flight and he missed his flight. He can't have as I have his check-in tag."

She ran inside the plane to check with the flight attendant where her grandson was.

In response, the attendant said: "No, I had no kids with me," according to the grandmother.

"I kept thinking about if somebody would've stolen my grandson," she added.

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The boy was "incorrectly boarded" on a flight to Orlando, according to Spirit Airlines.

"The child was always under the care and supervision of a Spirit Team Member, and as soon as we discovered the error, we took immediate steps to communicate with the family and reconnect them," the airline said in a statement on Saturday.

Once the mistake was discovered, the airline let the family know, the statement added.

"We take the safety and responsibility of transporting all of our guests seriously and are conducting an internal investigation," it continued. "We apologise to the family for this experience."