A Frontier Airlines flight had a computer malfunction after leaving Denver for Las Vegas late last week.
At 36,000 feet, while approaching Aspen, Colo., the Airbus lost pressure, oxygen masks dropped, and the plane descended before being diverted back to Denver, to which it returned safely.
The airline says the passengers and crew were never in danger.
Passenger Andrew Vos, of Fort Atkinson, Wis., took video as it all unfolded. (Click here to watch a report from CBS station KCNC-TV in Denver.)
One woman is heard crying loudly.
"People crying, people really hyperventilating and, after we got out of the mountains, they announced there was a cabin pressure failure," Vos said, adding, "Someone shouted, 'We're going down,"' and people became quite upset.
Aviation safety consultant Steve Cowell says that, while it was a disturbing event for the passengers, it was handled by the book.
"The pilots were up front with their masks on and they are initiating procedures they are trained for and practice every six months," Cowell said.
"While this was a frightening event for many passengers on the flight, there was no rapid decompression in the cabin or structural damage to the aircraft," a Frontier spokesperson told KCNC.
The plane was met by emergency equipment in Denver.