Aswan Dam assumption did not take into account the extent of perennial irrigation that was already present throughout Egypt decades before the high dam closure. By the 1950s only a small proportion of Upper Egypt had not been converted from basin (low transmission) to perennial (high transmission) irrigation. Expansion of perennial irrigation systems in Egypt did not depend on the high dam. In fact, within 15 years of the high dam closure there was solid evidence that biharzia was declining in Upper Egypt. S. haematobium has since disappeared altogether. Suggested reasons for this include improvements in irrigation practice. In the Nile Delta,
1969 Aswan Ilyushin Il-18 crash third try when it banked to the right and hit the left side of the runway. The starboard wing tore off and a fuel spillage followed which caused the crashed aircraft to burst into flames. The probable cause was determined to be that the "Pilot descended below the minimum safe altitude without having the runway lights clearly in sight. A contributory factor was fatigue arising from continuous working hours without suitable rest periods." 1969 Aswan Ilyushin Il-18 crash On 20 March 1969, a United Arab Airlines Ilyushin Il-18 crashed while attempting to land at Aswan Airport. 100 of the 105