According to the mother of the 15-year-old, who contacted ABC radio this morning, the girl and her sister, 16, were approached by the attendant during a flight from the Mudjimba airport to Melbourne.
The mother, named as Elizabeth, said the girls refused to tell the man their names but the attendant sent a Facebook friend request to the younger girl soon after the flight landed.
"He's accessing the names of passengers, particularly my daughters who are underage, and then he's using that information to contact them, and I find that really disturbing," she said.
Elizabeth said the man was still contacting his daughter asking why she had not added him as a friend.
A Jeststar spokesman said the matter was being investigated.
"Jetstar management are expeditiously looking into the matter at question," he said.
"We are viewing the allegations as serious but it’s important that we get all the information together and ensure that we're dealing with the facts of the matter."
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