About Aero Lloyd flight 1135:

On July 1, 2002, Aero Lloyd flight 1135, an Airbus A320-200, was running behind schedule and did not reach Friedrichshafen Airport until after the allotted arrival time for passenger flights. The region's Zürich-based traffic control centre was not expecting to handle any more landings that night and therefore only had a single controller working the late-night shift, despite regulations that required at least two controllers on duty at all times. Although flight 1135 ultimately landed safely, the controller's efforts to assist this flight had repeatedly distracted him from his prior responsibility to handle high-altitude traffic in the Lake Constance region; this was cited by investigators as a major contributing factor in the nearby mid-air collision above Überlingen, which occurred while flight 1135 was preparing to land.