Numerous VIP operators used various INS configurations. LTN-72,92, and various Carousel units. The only operator I know of that had the INS installed as OEM was Singapore when they operated maybe six or more 727 ADV. had the Carousel's installed. At the end of the original INS introduction the Carousel was having a very high degree of failure rates within the airline industry and in some cases it was less than 1000 hours between MTBF on the units. They simply became to expensive to operate thus the newer generation laser units started to take over.