ETHIOPIA has banned all flights over its giant new hydropower dam on the Blue Nile for security reasons, the head of its civil aviation authority has said. Ethiopia is locked in a dispute with Egypt and Sudan over its $4 billion Grand Ethiopian Renaissance Dam, which Cairo has said could threaten its main supply of water. "All flights have been banned to secure the dam," the director-general of the Ethiopian Civil Aviation Authority, Wesenyeleh Hunegnaw, told Reuters by phone. He declined to give more details on the reasons. Last week, air force chief Major General Yilma Merdasa told local media…