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Joint Precision Approach and Landing System (JPALS)
Precision Approach and Landing Capability (PALC)

The Joint Precision Approach and Landing System (JPALS) is a differential GPS that will provide a rapidly deployable,mobile, adverse weather, adverse terrain, day-night, and survivable precision approach and landing capability that supports joint service, civil, and multi-national interoperability. The Air Force's Global Access, Navigation, and Safety (GANS) program is a potential vehicle for collaboration. GANS is an umbrella avionics program that integrates GPS, navigation and safety equipment, Navigation Warfare (NAVWAR), avionics modernization, military ground-based infrastructure, Global Air Traffic Management (GATM), and the Joint Precision Approach and Landing System (JPALS).

The Joint Precision Approach and Landing System (JPALS) will allow aircraft to land on any suitable land or sea-based surface worldwide, while minimizing the impact to airfield operations because of a low ceiling or poor visibility. This next-generation approach and landing system will provide joint operational capability for U.S. forces to perform assigned conventional and special operations missions from fixed-base, tactical, shipboard, and austere environments under a wide range of meteorological and terrain conditions.

Existing civil and military systems do not satisfy JPALS requirements because they have a number of shortcomings and they limit joint operations. The Instrument Landing System (ILS) has complex siting requirements because of topography limitations, suffers from frequency congestion because of a finite number of available frequencies, and has frequency modulation interference problems in some areas. ILS is not deployable and is to be phased out by 2010 according to the Federal Radionavigation Plan. Precision Approach Radar (PAR) is the NATO standard, but it is airlift and manpower intensive. PAR is being phased out by the Air Force and has no civil interoperability. The Mobile Microwave Landing System (MMLS) provides no civil or allied interoperability. The Marine Remote Area Approach and Landing System and Instrument Carrier Landing System are not interoperable with Air Force, Army, civil users, or allies. The multiplicity of systems in itself hinders inter-Service, civil, and allied operations.

In 1992, the Assistant Secretary of Defense for C3I directed a study to analyze existing emerging PALS technologies. Tasking was passed through the Air Force to the DoD Policy Board on Federal Aviation, which chartered the Precision Landing Study Advisory Group (PLSAG) to produce a JPALS Mission Needs Statement (MNS). The Joint Requirements Oversight Council validated the MNS in August 1995.

The crash of a U.S. military transport in Bosnia in 1996, while flying a nonprecision approach in adverse weather, highlighted the need for a near-term, rapidly deployable precision approach system. As a result, the Air Mobility Command is pursuing an initiative to field a precision approach system to solve problems like the one encountered in Bosnia. In September 1996, the Commander of Transportation Command requested accelerated assessment for improved capability for 12 C-5s and 12 C-141s, in addition to 35 C-17s. To provide a near-term, austere precision landing capability, MMLS with the Commercial Microwave Landing System Avionics and the Precision Landing System Receiver are being examined as the material solution. The JPALS overarching integrating process team (OIPT) concurred with the material solution and noted that implementation was contingent upon identifying funds.

Developmental tests using the C-135 "Speckled Trout" aircraft demonstrated the capability to fly precision approaches using a local area differential GPS system. An analysis of alternatives (AoA) also explored using a microwave Landing System, Precision Approach Radar, and Tactical Transponder Landing System. The AoA also looked at civil Wide Area Augmentation System for use in domestic airspace and Enhanced Vision Systems in low visibility operations, as well as an upgraded Automatic Carrier Landing System for shipboard backup. A few key parameters drove the analysis of alternatives, particularly during the initial screening process. For JPALS, these key parameters were interoperability, likelihood of international standardization, level of modification required for commercial off-the-shelf products, deployability, schedule, and cost. For the near-term solution, schedule was paramount. System maturity and deployability were additional factors.

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