Some Delta Airlines passengers were left to wonder as their plane became engulfed in a strange smoke-like mist prior to take-off in a flight on Sunday night.

Even more bizarrely, the flight crew on the Florida to New York service didn’t bother addressing the foggy elephant in the room.

Delta plane
The plane filled with a smoke-like mist before take-off, unsettling passengers. (PA/AAP)

One passenger claimed the crew instead “made a joke of it,” fuelling the confusion around the odourless mist even further.

Passenger Amanda Goncalves captured footage of the mystery fog, and later told CBS that a crew member joked they were “practicing for their Halloween haunted house”.

Watch Goncalves footage in the clip above.

The mist was likely caused by the hot air and high humidity outside the plane reacting with the cabin air conditioning, a Delta spokesperson told Fox News.

The flight touched down in New York without any issues.

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