Task: Question Understanding
Input (English): Context : The 1957 Aqaba Valetta accident happened on the 17 April 1957 when a twin-engined Vickers Valetta C.1 transport aircraft, serial number VW832, of 84 Squadron, Royal Air Force crashed and was destroyed after departing from Aqaba Airport in Jordan following wing failure due to turbulence. 
Question : What is the full date that 1957 Aqaba Valetta accident crashed on?
Output (English): point in time