 Decision bars are always located 1000′ farther away from the threshold in the direction of the arriving aircraft, and serve as a visible horizon to ease the transition from instrument flight to visual flight.Approach lighting systems are designed to allow the pilot to quickly and positively identify visibility distances in Instrument meteorological conditions.For example, if the aircraft is at the middle marker, and the middle marker is located 3600 feet from the threshold, the Decision Bar is 2600 feet ahead.