Two South Korean air force planes reportedly collided in mid-air shortly after takeoff during flight training and crashed near their base on Apr. 1, killing all four pilots aboard the planes, authorities said. The two planes, identified as KT-1 trainer aircraft, collided five minutes after taking off from their base in the southeastern city of Sacheon at 1.37 p.m. on Friday, Yonhap News Agency (YNA) reported, citing the air force and local disaster response officials. Local officials earlier said that three pilots were killed and one was missing in the crash. The fourth pilot was later found dead. The air force said that all two student pilots and two flight instructors aboard the two planes attempted an emergency escape but they did not survive the crash. More than 60 firefighters and emergency responders, as well as some 130 troops, had been dispatched to the crash sites for a search operation. …