A Singapore Airlines plane was hit by sudden turbulence Tuesday while flying from London to Singapore, killing one passenger and injuring more than 70 others, according to officials. Several passengers remain in critical condition. Flight SQ321, a Boeing 777 with 211 passengers and 18 crew members on board, was 10 hours into the journey and flying over Myanmar when it was hit by turbulence with little to no warning, according to the airline and flight data. “Suddenly there was a very dramatic drop so everyone seated and not wearing seatbelt was launched immediately into the ceiling,” Malaysian…