A Loran-G Airborne Navigator

ABSTRACT A Loran-C Airborne Navigator for use in Coast Guard helicopters is described. Cockpit mounted, the device weighs only 12 pounds, uses LSI circuitry extensively and includes a microcomputer and a completely automatic Loran-C receiver. The navigator generates steering information relative to a track1ine defined by up to nine operator entered waypoints. The Coast Guard is conducting an extensive laboratory and operational flight evaluation program. Many test scenarios are similar to offshore helicopter operations. Results to date indicate the receiver will perform satisfactorily in the Coastal Confluence Zone Loran-C system. Flight testing on prototype systems indicates that navigation accuracy better than 190 meters is probable and rendezvous to within 10 meters have been accomplished. INTRODUCTION The U. S. Coast Guard is installing Loran-C transmitting and monitoring stations which will provide coverage in the coastal and Great Lakes regions by 1980. These areas are where Coast Guard vessels and aircraft usually operate. Loran-C receivers are available to meet the needs of vessels, but do not meet the needs of aircraft adequately. In April of 1975, a contract was awarded to the Teledyne Systems Company of Northridge, California to develop a miniaturized Loran-C airborne navigator which would be used to evaluate the use of Loran-C by Coast Guard aircraft. The navigator has been delivered and is currently undergoing, evaluation by the Coast Guard. Comparison of-the needs of Coast Guard helicopters to those of civilian helicopters operating in support of offshore industries shows a remarkable degree of coincidence. Both operate beyond the range of VOR/111E, both require accurate navigation to a physically small destination, both have severe weight and volume constraints, and both need to minimize the pilot training required to operate the navigation system. Even tile desirable features are similar since both would like to store often used destinations in memory, avoid long initialization periods, and incorporate some means of position monitoring from the operating base which would improve safety and effectiveness of operations. The navigator described in this paper should meet most of-the needs of offshore helicopter and fixed wing aircraft operators as well as the Coast Guard's. The manufacturer is prepared to offer it to the civilian community. Area navigation (RNAV) is a method of navigation that permits aircraft operations on any desired course within the coverage of station referenced navigation signals or within the limits of self-contained system capability.(3) The pilot defines the desired track by specifying a point of departure, a point of destination and intermediate points if applicable. These geographical points are called waypoints and can be referenced to either Latitude and Longitude or the navigation aid system in use. The Loran-C navigator described in this paper is designed to permit area navigation in the horizontal plane.