Delta passengers texted their loved ones as their plane plunged 30,000 feet in seven minutes.
The flight from Atlanta to Fort Lauderdale was halfway through its route when it rapidly dropped from an altitude 39,000 feet to 10,000 feet.
Delta later confirmed the unanticipated descent was caused by cabin pressurisation irregularity en route.
Panic broke out on the flight when it started falling, with flight attendants trying to rein in the chaos as passengers texted their loved ones.
After the descent, the flight diverted to Tampa and landed safely 28 minutes later before passengers got off.
Since landing, passengers have recounted the terrifying ordeal to several media outlets.
"Out of nowhere, I felt what felt like a sort of a rapid descent," Harris DeWoskin told WFTS.
"We started dropping in altitude and then the oxygen masks dropped from the top of the plane. Chaos sort of ensued amongst the passengers."
DeWoskin said he contacted his girlfriend and family to let them know what was happening aboard the aircraft.
"One of the flight attendants, I believe, grabbed the intercom and was just repeating over the intercom stating: "Do not panic! Do not panic!'," he said.
"But, obviously, it's a hectic moment so, the passengers around me, a lot of people, were kind of hyperventilating."
DeWoskin and others shared photos and videos of passengers desperately looking for answers after oxygen masks dropped from the overhead compartment.
"Life is fragile. There was a scary 60 to 90 seconds where we really didn't know what was going on," Dewoskin said.
"You are 15,000 feet in the air — it's a scary moment for sure."
Preliminary FlightAware data shows the plane descended from 39,000 feet at 4.34pm to 9975 feet at 4.42pm (local time).
A Delta Air Lines spokesperson told the Independent: "We apologise to our customers on flight 2353 from Atlanta to Fort Lauderdale, which diverted to Tampa out of an abundance of caution and landed without incident following a cabin pressurisation irregularity en route."
The airline said passengers were transported from Tampa to Fort Lauderdale by bus, arriving last night.
The aircraft is currently being evaluated by maintenance technicians.