Optical landing system An optical landing system ( OLS ) ( nicknamed " meatball " or simply , " Ball " ) is used to give glidepath information to pilots in the terminal phase of landing on an aircraft carrier . From the beginning of aircraft landing on ships in the 1920s to the introduction of OLSs , pilots relied solely on their visual perception of the landing area and the aid of the Landing Signal Officer ( LSO in the US Navy , or " batsman " in the Commonwealth navies ) . LSOs used colored flags , cloth paddles and lighted wands . Components . An optical landing system has several related components : the lights used to give visual cues to approaching aircraft , the light control system , and the mounting system . Lights . At least three sets of lights are used , regardless of the actual technology : Additionally , some ( particularly later ) optical landing systems include additional lamps : Light controls . Collectively , the apparatus that the lights are mounted on is called “ the lens ” . It is turned on / off and brightness is adjusted at the lens itself for ground based units , and remotely for shipboard units . In both cases , the lens is connected to a hand - controller ( called the “ pickle ” ) used by the LSOs . The pickle has buttons that control the wave - off and cut lights . Light mounting . For shore - based Optical Landing Systems , the lights are typically mounted on a mobile unit that plugs into a power source . Once set up and calibrated , there are no moving parts to the unit . Shipboard units are much more complicated as they must be gyroscopically stabilized to compensate for ship movement . Additionally , shipboard units are mechanically moved ( the “ roll angle ” ) to adjust the touchdown point of each aircraft . With this adjustment , the tailhook touchdown point can be precisely targeted based on the tailhook - to - pilot ’ s eye distance for each aircraft type . Mirror landing aid . The first OLS was the mirror landing aid , one of several British inventions made after the Second World War revolutionising the design of aircraft carriers . The others were the steam catapult and the angled flight deck . The Mirror Landing Aid was invented by Nicholas Goodhart . It was tested on the carriers HMS " Illustrious " and HMS " Indomitable " before being introduced on British carriers in 1954 and on US carriers in 1955 . The mirror landing aid was a gyroscopically - controlled concave mirror on the port side of the flight deck . On either side of the mirror was a line of green coloured " datum lights " . A bright orange " source " light was shone into the mirror creating the " ball " ( or " meatball " in later USN parlance ) which could be seen by the aviator who was about to land . The position of the ball compared to the datum lights indicated the aircraft ' s position in relation to the desired glidepath : if the ball was above the datum , the plane was high ; below the datum , the plane was low ; between the datum , the plane was on glidepath . The gyro stabilisation compensated for much of the movement of the flight deck due to the sea , giving a constant glidepath . Initially , the device was thought able to allow the pilot to land without direction from the LSO . However , accident rates actually increased upon the system ' s initial introduction , so the current system of including the LSO was developed . This development , along with the others mentioned , contributed to the US carrier landing accident rate plummeting from 35 per 10 , 000 landings in 1954 to 7 per 10 , 000 landings in 1957 . The LSO , who is a specially qualified and experienced Navy pilot , provides additional input to the pilot via radios , advising of power requirements , position relative to glide path and centerline . The LSO can also use a combination of lights attached to the OLS to indicate " go around " using the bright red , flashing wave off lights . Additional signals , such as " cleared to land , " " add power , " or " divert " can be signaled using with a row of green " cut " lights or a combination thereof . Fresnel lens optical landing system ( FLOLS ) . Later systems kept the same basic function of the mirror landing aid , but upgraded components and functionality . The concave mirror , source light combination was replaced with a series of fresnel lens es . The Mk 6 Mod 3 FLOLS was tested in 1970 and had not changed much , except for when ship ’ s heave was taken into account with an Inertial Stabilization system . These systems are still in wide use on runways at US Naval Air Stations . Improved fresnel lens optical landing system ( IFLOLS ) . The IFLOLS , designed by engineers at NAEC Lakehurst , NJ , keeps the same basic design but improves on the FLOLS , giving a more precise indication of aircraft position on the glideslope . A prototype IFLOLS was tested on board USS George Washington ( CVN - 73 ) in 1997 and every deploying aircraft carrier since 2004 has had the system . The Improved Fresnel Lens Optical Landing System , IFLOLS , uses a fiber optic " source " light , projected through lenses to present a sharper , crisper light . This has enabled pilots to begin to fly " the ball " further away from the ship making the transition from instrument flight to visual flight smoother . Additional improvements include better deck motion compensation due to internalization of the mechanism . Manually Operated Visual Landing Aid System ( MOVLAS ) . The MOVLAS is a backup visual landing aid system used when the primary optical system ( FLOLS ) is inoperable , stabilization limits are exceeded or unreliable ( primarily due to extreme sea states causing a pitching deck ) , and for pilot / LSO training . The system is designed to present glideslope information in the same visual form presented by the FLOLS . There are three installation modes aboard ship : STATION 1 is immediately in front of the FLOLS and utilizes the FLOLS waveoff , datum , and cut light displays . STATION 2 and 3 are independent of the FLOLS and are located on the flight deck port and starboard side respectively . MOVLAS is nothing more than a vertical series of orange lamps manually controlled by the LSO with a hand controller to simulate the ball . Pitching deck . The IFLOLS has three modes of stabilization . Point , Line , and Inertial . The most precise is inertial stabilization . In point stabilization , the glide slope is fixed around a point 2500 feet aft of the lens . In Line , the glide path is stabilized to infinity . As the deck pitches and rolls , the source lights are rolled to maintain a steady glideslope fixed in space . Inertial stabilization functions like Line , but also compensates for the flight deck heave ( the straight up and down component of deck motion ) . If the IFLOLS cannot keep up with the motion of the deck , the LSO can switch to the MOVLAS or simply perform " LSO talk downs . " Only the most experienced LSOs will perform talk downs or control aircraft with MOVLAS during heavy sea states .