Improving detection technique for flight recorders of the distress airplanes crashed into ocean by integrating inertial navigation system into underwater locator beacon

Flight recorder, used to analyze distress reasons, is equipped with underwater locator beacon (ULB) for being detected and recovered easily in sea. According to the recovery report for the Air France flight no. AF447 distress airplane, it nearly took two years and cost 40 million US dollars to search and recover the flight recorders. Apparently, future aviation safety could be greatly improved if earlier recovery of the flight recorders would reveal the crash reasons sooner. Therefore, this paper is aimed to develop an enhanced ULB, which integrates inexpensive inertial navigation system (INS) into ULB, for a cost-effective and time-saving operation of search and recovery in the future. This new equipment is anticipated to directly provide the location of flight recorders to the search and recovery authority. From the static and dynamic tests, maximum position errors are below 50 m when the standalone INS operates in a duty cycle of 78 seconds. From the case report of AF447 aircraft crush, the time taken from 38,000 feet (= 11,582 m) descent to sea level is about 3 minutes and 30 seconds. Over this time frame, the maximum position error is about 140 m owing to the nearly linear drift property of the INS. Thus, the proposed INS-aided ULB.