It's practically an epidemic. Just this month, authorities have received more than 50 threats made against airlines online, most of them through Twitter.

On Tuesday, an American Airlines flight bound from Los Angeles to Chicago was the subject of a tweet that read, "@AmericanAir No, There is a bomb on Flight 1192, We Are ISIS, we will (expletive) you guys up, #ISIS," reported USA Today. And NBC News reports that at least eight threats were posted on Twitter Tuesday afternoon from three different accounts.

That was after a weekend in which three flights were disrupted because of Twitter terror threats. A Delta Air Lines flight from Los Angeles to Orlando was diverted to Dallas on Sunday after bomb threats were made on Twitter. Two flights -- one JetBlue, one SkyWest -- were evacuated away from other aircraft upon arrival in Seattle on Sunday for similar threats.

Passengers are understandably rattled. "To see someone say, 'We are ISIS, we are here, we're on the plane,' I mean, that was absolutely terrifying," said one passenger, who saw a tweet made against her Delta flight while in the air.

But do you really need to fear for your safety as a result of these Twitter rants? The truth is, terrorists do not announce themselves this way, law enforcement officials agree.

"In the history of aviation sabotage, I don't believe there's ever been a threat called in where there's actually been a bomb," Douglas Laird, a consultant who is a former security director at Northwest Airlines, told USA Today.

Of course, that doesn't mean that such Twitter postings aren't taken seriously. Airlines must report all security threats, and the FBI investigates all of them.

"They make a judgment call as to whether they should take it seriously or whether there's not complete information to act on," University of Denver aviation professor Jeff Price told USA Today. "They take all threats seriously, but they have to decide whether they should respond and take it to another level."