History of the Flight
The Airbus A380, registration 9V-SKJ, operated by Singapore Airlines, was on a scheduled passenger flight from Singapore Changi Airport to Mumbai Airport. Before departure, the flight crew briefed the In-Flight Supervisor about forecast adverse weather near Mumbai and advised earlier cabin preparation for arrival.
While descending from Flight Level 380 to 150, the flight crew observed a patch of isolated cumulonimbus clouds on the weather radar display. They requested and received ATC approval to turn left heading 300° to remain at least 10 nautical miles clear of the green edge of the weather returns. The fasten seat belt sign was turned on, and a corresponding PA announcement was made.
The flight crew declined two ATC requests to fly direct to waypoint MB372, as that would have entered the cumulonimbus clouds. After passing the observed weather, they received approval to track direct to MB372.
During the descent, the flight crew felt two brief episodes of light to moderate turbulence. About four and a half minutes after the seat belt sign was activated, the Senior First Officer (pilot flying) made a PA announcement instructing cabin crew to be seated. Immediately after (with a five-second interval according to flight recorder data), the aircraft encountered severe turbulence lasting about two seconds. Some passengers and cabin crew were thrown toward the ceiling. At the time, the cabin crew had not yet completed securing the cabin or themselves.
The flight crew did not see clouds outside or weather cells on the radar during the severe turbulence. They did not declare an emergency to ATC, believing the aircraft was near final approach and that such a declaration could cause delays. They requested medical assistance through the operator's ground handling agent upon landing. The aircraft landed without further incident, and injured persons received medical attention.
Injuries to Persons
Two passengers and two cabin crew members sustained serious injuries. One passenger (lower deck economy seat, not wearing seat belt) had rib area injuries; the other (upper deck economy seat) suffered a dislocated right shoulder and a cut to the stomach while leaving a lavatory. One cabin crew member (upper deck galley) fractured a left wrist; another (upper deck) fractured a rib cage.
Damage to Aircraft
The report notes damage to the aircraft, but specific items are not listed in the provided source.
Investigation
The Air Accident Investigation Bureau of India classified the event as an accident and delegated the investigation to the Air Accident Investigation Bureau of Singapore. The occurrence was most probably a case of encounter with clear air turbulence.