Singapore Airlines: Welsh passenger tried to save heart-attack victim BBC.comWhat Turbulence Did to Singapore Airlines Flight SQ321 The New York TimesInvestigators analysing data from SQ321’s flight recorders: Chee Hong Tat CNASingapore Airlines changes seatbelt sign policy following fatal turbulence incident CNN‘I Was Dripping Blood’: Inside One of the Worst Turbulence Accidents Ever The Wall Street Journal