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.
Sources and Resources
http://www.fas.org/man/dod-101/sys/ac/equip/jpals.htm
Maintained by Robert Sherman
Originally created by John Pike
Updated Tuesday, January 19, 1999 5:33:16 PM