Developing a case for an improved aircraft carrier visual landing aid for glideslope control

Landing a fixed-wing aircraft on board an aircraft earner, while performed numerous times around the world each day, is considered by many to be one of the most difficult tasks in modern-day aviation. The aircraft carrier landing area is significantly smaller than a standard runway and is normally moving away from the approaching aircraft. When the carrier experiences adverse weather or sea states, the landing area frequently translates not only horizontally and vertically, but also in combinations of the two, producing movements not experienced on a normal airfield runway. The task of a carrier pilot is to fly an approach precise enough to have the aircraft’s arresting hook touch down within a 40 foot long section of flight deck in-between the second and third of four arresting wires. The first naval aviators were expected to use their own judgement to execute a successful approach. Shortly thereafter, a Landing Signals Officer (LSO), who was also an experienced carrier pilot, was placed on the flight deck with a highly visible set of paddles to help guide the approaching pilot to the appropriate touchdown point. In time, an optical landing system consisting of a mirror and light source was developed to assist the pilots in flying the proper glideslope during carrier approaches. This mirror system was eventually replaced by an apparatus consisting of five Fresnel lens assemblies stacked vertically along with a set of six lights extending horizontally from each side to be used as datums. This Fresnel Lens Optical Landing System (FLOLS) is the current landing aid in use on every U.S. aircraft carrier in service today. The FLOLS, although reliable, consists of 1950’s and 60’s technology. It has limited capability to compensate for the carrier’s movement and is becoming increasingly more expensive to maintain and operate. A new landing aid, the Improved Fresnel Lens Optical Landing System (IFLOLS) has been developed and has recently been approved for installation on all fleet aircraft carriers and several Naval Air Stations. The IFLOLS provides much improved sensitivity and clarity to pilots, greater capability to compensate for ship’s movement, and increased maintainability and reliability as compared to the FLOLS. This thesis will examine the procedures used by aircraft to operate around the aircraft carrier, the history of Visual Approach Aids (VLA’s), problems associated with the FLOLS, and the suitability of the IFLOLS to replace the FLOLS as the primary carrier visual landing aid. IFLOLS data will come primarily from technical reports generated during a lengthy evaluation conducted from September of 1996 through April of 1998 by the Naval Air Warfare Center Aircraft Division (NAWCAD). The IFLOLS evaluation was completed prior to the author’s arrival at NAWCAD. The research performed was purely historical and the author played no part in either the evaluation or acquisition process of the IFLOLS.