It’s another rough day in the skies for Delta -- this time, a plane’s cabin filled with thick smoke mid-flight, leading to an emergency landing and evacuation of everyone onboard.

The Boeing 717 aircraft was en route to Columbia, South Carolina Monday morning when "haze inside the aircraft" was reported, forcing an immediate return to Atlanta, with all 94 passengers evacuated via emergency inflatable slides.

One passenger's video shows smoke permeating the cabin in the mid-air flight, with everyone holding clothes over their faces to protect themselves. Later footage shows them safely on the tarmac after debarking.

There were two pilots and three flight attendants aboard -- and all were safe and sound, with Atlanta Fire Rescue assisting with the deplaning.

A spokesperson for Hartsfield-Jackson Atlanta International Airport told TMZ ... "Airfield operations are normal at this time."

The Federal Aviation Administration is now investigating the incident.

This latest scare adds to a series of unsettling airline incidents -- Just a week ago, another Delta plane flipped upside down at a Toronto airport after landing, and there have been several other high-profile crashes this year.

With all that, it’s no wonder passengers are feeling a bit jittery about air travel right now.