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A Landing Signal Officer (LSO) is a Naval Aviator specially trained to facilitate the "safe and expeditious recovery" of naval aircraft aboard aircraft carriers. Originally LSOs were responsible for bringing aircraft aboard ship using hand signals. Since the introduction of optical landing systems in the 1950s, LSOs assist pilots by giving information via radio handsets.
In the U.S. Navy, aircraft carrier operations began with USS Langley (CV-1) in 1922. Langleys initial flight operations were on an experimental basis to learn what worked and what didn't. The first pilots had no signaling system for assistance from shipboard personnel. Langleys first executive officer, Kenneth Whiting, had a hand-cranked movie camera film every landing to aid in evaluation of landing technique. When not flying, Commander Whiting observed all landings from the aft port corner of the flight deck. Commander Whiting's position remained visible to landing pilots in critical touchdown attitudes when the nose of the aircraft might obscure the pilot's view straight ahead. Pilots found Commander Whiting's body language helpful and suggested an experienced pilot be assigned to occupy that position, using agreed signals which evolved with experience. These Landing Signal Officers or Landing Safety Officers (LSOs) faced the incoming plane and held colored flags for improved visibility. Because LSOs used colored paddles, flags, or wands well into the jet age, the officers became unofficially known as "paddles" (US), or "batsmen" (UK). They are still referred thus to this day, and the LSO trade is referred to as "waving".
From the 1920s into the 1950s, U.S. and Royal Navy LSOs used a variety of signals to assist pilots landing aboard aircraft carriers. The signals provided information on lineup with the deck, height relative to proper glide slope, angle of attack (fast or slow), and whether the plane's tailhook and wheels were down.
The final signal was "the cut" (a slashing motion at the throat) ordering the pilot to reduce power and land the aircraft. In a properly executed landing, the aircraft's tailhook snagged an arresting wire that brought the plane to a halt. A "waveoff" was a mandatory order to abort the landing and go around for another attempt. Sometimes a proper approach drew a waveoff if the deck was "fouled" with aircraft or personnel in the landing area.
The difference between American and British LSOs was the nature of their signals. Generally, U.S. Navy signals were advisory, indicating whether the plane was on glide slope, too high, too low, etc. Royal Navy signals were usually mandatory, ordering the pilot to add power, come port, etc. When "crossdecking" with one another, the two navies had to decide whether to use the U.S. or British system.
In contrast, the Imperial Japanese Navy had no LSOs. Instead, its carriers employed a system of colored lights much like today's general aviation runway edge lights at most airports. However, each Japanese carrier assigned a sailor to wave a red flag in case a landing was to be aborted.
From the late 1950s, carriers evolved from the original straight or axial-deck configuration into the angled flight deck, with an optical landing system (OLS) providing glide slope information to the pilot. 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 system of using both the OLS and the LSO was developed. This development, along with other safety improvements, 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.
Together with the OLS, the LSO provides input to the pilot via a radio handset (that looks like a telephone handset), advising of power requirements, position relative to glide path and centerline. The LSO also holds a "pickle" that controls 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 an upper row of green "cut" lights or a combination thereof. Often, pictures of LSOs show them holding the pickle switch over their head. This is done as a visual reminder to the LSOs that the deck is "fouled" with aircraft or personnel in the landing area. Once the deck becomes clear, the LSOs are free to lower the pickle.
LSOs have been rated carrier pilots since the end of World War II, but during the war the need was such that some non-aviators were trained. Because of the importance of LSOs, the duty offers great responsibility for junior officers, generally lieutenants (junior grade) to lieutenant commander. Prospective LSOs are selected among junior pilots from each fixed wing USN and USMC carrier aviation squadron. The first qualification they receive is a “field qualification,” which allows them to wave aircraft at shore runways during Field Carrier Landing Practice (FCLPs) without supervision. The LSO next attends the LSO School at NAS Oceana, Virginia, for Initial Formal Ground Training. Additional qualifications include:
LSOs typically work in teams aboard ship. In an example arrangement, four teams of 6-8 LSOs would fly for three days, then wave on the fourth day.
All LSOs work directly for the Air Wing LSO (aka "Cag Paddles"), who is ultimately responsible for the safe and expeditious recovery of aircraft, and for training/qualifying junior LSOs. There are typically two Air Wing LSOs per Air Wing, and one of them is usually on the LSO platform for every landing.
The Controlling LSO is primarily responsible for aircraft glideslope and angle of attack. He or she also issues a "grade" for each landing.
The Backup LSO is typically more experienced than the Controlling LSO, and is primarily responsible for aircraft lineup and ensuring that the landing area is clear. He helps in the grading. He may provide glideslope/angle of attack commentary on that grade.
This individual monitors deck status as either "clear" or "foul." Foul deck is further delineated based on what is "fouling" the landing area. With personnel or aircraft in the landing area, the "waveoff window" is adjusted so that approaching aircraft get no lower than 100 feet above the highest obstacle in the landing area. If there is neither personnel nor aircraft in the landing area but the deck is still foul, aircraft must be waved off in time to pass no lower than 10 feet above the landing area.
LSOs do their waving from the LSO Platform, which is on the port side of the ship aft of the port side aircraft elevator. It is protected by a wind deflector, and has an escape area into which deck personnel can jump in an emergency. The platform is outfitted with communications gear, deck status and ship indications, as well as controls for the OLS.
The LSO work station consists of three pickle switches, a wind screen, the LSO Base Console and a HUD unit, with actual configuration varying dependent on ship type, age and technology.
Integrated Launch And Recovery Television Surveillance System (ILARTS) provides the LSO with a reference for aircraft lineup and glideslope information during recovery operations, and is used as a debriefing medium for pilots. Additionally, the system is used for recording significant flight deck events and, when necessary, for mishap or incident analysis.
Every carrier landing made by US pilots is graded for safety and technique, using a complex shorthand to denote what each aircraft did during various phases of each approach. Approaches are divided into parts:
Deviations from optimal glideslope, centerline, and angle of attack are noted for each phase, resulting in an overall grade. Grades are debriefed to each pilot by the LSO teams after each cycle. Average grades are computed for each pilot, resulting in a highly competitive pecking order of pilot landing skill throughout the airwing.
It is a common misconception that pilots are graded based on the wire their tailhook catches on the pass. LSOs don't look at where the plane landed, they look at how it got there. It is possible for a pilot to fly a safe pass and land on a 1 wire, it is also possible that a plane catches a 3 wire and the landing is unsafe. Under normal circumstances, on Nimitz class carriers the targeted hook touchdown point is halfway between the two wire and the three wire.
LSOs grade the pass and write a comment, in shorthand, for use in the LSO-Pilot debrief. An example comment might read, "High, a little overshooting start, fly through down on comeback in the middle, low in close to at the ramp. Fair-2" -meaning the aircraft was high at the start of the approach and was slightly overshot the landing area centerline. As the pilot corrected to centerline, he did not add enough power so he flew through the glideslope from high to low. The LSO likely would have given the pilot a signal at this time to add power. For the last portion of the approach, the aircraft remained below glideslope (but was on centerline because of the lack of a comment), touching down prior to the target 3-wire. The pilot caught the 2 wire, and received a grade of "fair".
The LSO in popular culture is romantically represented by "Beer Barrel", the colorful officer in James Michener's best-seller The Bridges at Toko-Ri. Actor Robert Strauss played the role in the 1954 motion picture.
The CBS television series JAG had several episodes centering on LSOs.
G.I. Joe produced a 1/6 scale uniform and accessories for the LSO.