CNN —Passengers on a Singapore Airlines flight hit by severe turbulence on Tuesday described a sudden, dramatic drop as “all hell broke loose” on board the Boeing airliner carrying 229 passengers and crew. Flight SQ321 was cruising at 37,000 feet from London to Singapore when flight tracking data shows the plane rapidly plunged before climbing several hundred feet, then repeated the dip and ascent, for about 90 seconds. At first, “the flight was perfectly normal,” said passenger Andrew Davies, who was traveling to New Zealand for business. He described the flight as “quite smooth … I don’t remember any turbulence at all.”Many passengers were having breakfast at the time of the incident. The interior of Singapore Airline flight SQ321 is pictured after an emergency landing at Bangkok's Suvarnabhumi International Airport, Thailand, on May 21.

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Persons: ”, Andrew Davies, ” Davies, Reuters Davies, Geoff Kitchen, Davies, Dzafran Azmir, Azmir, Goh Choon, Kittipong Kittikachorn, Kitchen, Goh, Kitchen’s Organizations: CNN, Passengers, Singapore Airlines, Boeing, Singapore Airline, Reuters, Briton, Facebook, Singapore’s Ministry of Transport, Thai, US National Transportation Safety Locations: London, Singapore, New Zealand, Thailand, Bangkok, Australia, Malaysia, United Kingdom , New Zealand, Spain, United States, Ireland