Local Area Augmentation System

The Local Area Augmentation System (LAAS) is an all-weather aircraft landing system based on real-time differential correction of the GPS signal. Local reference receivers Located around the airport send data to a central location at the airport . This data is used to formulate a correction message, which is then transmitted to users via a VHF Data Link . A receiver on an aircraft uses this information to correct GPS signals, which then provides a standard ILS -style display to use while flying a precision approach . The FAA has stopped using the term LAAS and has transitioned to the International Civil Aviation Organization(ICAO) terminology of Ground-Based Augmentation System (GBAS). [1] The FAA has indefinitely delayed plans for federal GBAS acquisition, the system can be purchased by air and non-Federal navigation aid. [2]

History

The International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPS), Annex 10 on Radio-frequency Navigation provides international standards for GPS to support precision landing. The history of these standards can be traced back to the United States by the Federal Aviation Administration to a Local Area Augmentation System (LAAS). Many references still refer to LAAS, although the current international terminology is GBAS and GBAS Landing System (GLS).

GBAS monitors GNSS satellites and provides correction messages to users in the vicinity of the GBAS station. The use of the GPS to detect the anomalous behavior of a satellite is an important issue. The GBAS provides corrections to the GPS signals with accurate approach operations. GBAS works, see GBAS-How It Works. [3]

Current GBAS standards only GNSS frequency and support landings to Category-1 minima. These GBAS systems are identified as GBAS Approach Service Type C (GAST-C). Draft requirements for a GAST-D system are under review by ICAO. A GAST-D system will support operations to Category-III minima. Many organizations are conducting research in multi-frequency GBAS. Other efforts are exploring the addition of Galileo corrections for GBAS.

Honeywell has developed a Non-Federal CAT-1 GBAS that has received System Design Approval (SDA) from the Federal Aviation Administration (FAA) in September 2009 [1]. The GBAS facility at Newark Liberty International Airport achieved Operational Approval on Sept. 28, 2012. [4] A second GBAS installed at Houston Intercontinental Airport received Operational Approval on April 23, 2013. [5] Honeywell systems are also internationally Operational system in Bremen, Germany. Additional systems are installed in the process of being installed. Operational approval of several more systems is expected shortly.

Operation

Local reference receivers are located around an airport at precisely surveyed locations. The signal from the GPS constellation is used to calculate the position of the LAAS ground station, which is then compared to its precisely surveyed position. This data is used to formulate a correction message which is transmitted to users via a VHF data link. A receiver on the aircraft uses this information to correct the GPS signals it receives. This information is used to create an ILS-type display for aircraft approach and landing purposes. Honeywell’s CAT I system provides precision approach service within a radius of 23 NM surrounding a single airport. LAAS mitigates GPS threats in the Local Area to a much greater accuracy than WAAS and therefore provides a higher level of service not attainable by WAAS. LAAS ‘ S VHF uplink signal is currently being sent to the frequency band from 108 MHz to 118 MHz with existing ILS localizer and VOR navigational aids. LAAS uses a Time Division Multiple Access (TDMA) technology in servicing the entire airport with a single frequency allocation. With future replacement of ILS, LAAS will reduce the congested VHF NAV band.

Accuracy

The current Category-1 (GAST-C) GBAS achieves a Category I Precision Approach of 16 m laterally and 4 m vertically. [6] The goal of a to-be developed GAST-D GBAS is to provide Category III Precision Approach capability. RTCA DO-245A, Minimum Aviation System Performance Standards for Local Area Augmentation System (LAAS) . The GAST-D GBAS will allow aircraft to land with zero visibility using ‘autoland’ systems.

Benefits

One of the primary benefits of LAAS is that it can be used for multiple precision approaches within the local area. For example, if Chicago O’Hare has twelve runway ends, each with a separate ILS, all twelve ILS facilities can be replaced with a single LAAS system. ILS equipment. This equipment has been tested and found to comply with the limits for a.

Another benefit is the potential for approaches that are not straight-in. Aircraft equipped with LAAS technology can utilize curved or complex approaches such that they could be flown on to avoid obstacles or to decrease noise levels in areas surrounding an airport. This technology shares similar characteristics with the older Microwave Landing System (MLS) Approaches, Commonly seen in Europe. Both systems allow lower visibility requirements are complex approaches That traditional Wide Area Augmentation Systems (WAAS) and Instrument Landing Systems (ILS) couldn’t allow. Citation needed ]

The LAA and WAAS capability. The FAA also has a single set of navigational equipments . This NDB ‘s, DME , VOR , ILS , MLS and GPS receivers . The FAA hopes this will result in decreased cost to the airlines and passengers as well as general aviation .

Drawbacks

LAAS shares the drawbacks of all RF landing systems; (Or intentional or accidental), and.

Variations

The Joint Precision Approach and Landing System (JPALS) is a similar system for military use. Honeywell has developed the SLS-4000 (SLS-4000) Honeywell International Satellite Landing System (SLS-4000) which received System Design Approval (SDA) from the FAA on September 3, -4000 Block 1) in September 2012. [2] [7]

Future

The FAA’s National Airspace System (NAS) Enterprise Architecture (EA) is the blueprint for transforming the current NAS to the Next Generation Air Transportation System (NextGen). The NAS Service Roadmaps for the future. They show the evolution of major FAA investments / programs in today’s NAS services to meet the future demand. The GBAS Precision Approaches in the Next Generation Implementation Plan.

The FAA is expected to replace legacy navigation systems with satellite navigation technology; Non-Federal navigation aid. The United States Government has adopted a non-federal navigation aid system. GBA systems and seek international standardization. [2]

See also

  • Acronyms and abbreviations in avionics
  • Differential GPS
  • Global Positioning System
  • GPS and Geo Augmented Navigation
  • Instrument Landing System : ILS
  • Joint Precision Approach and Landing System is a similar system for military use.
  • Precision approach
  • WAAS
  • EGNOS
  • Autoland

References

  1. Jump up^ “GNSS Frequently Asked Questions – GBAS” . Www.faa.gov . Retrieved 2016-05-19 .
  2. ^ Jump up to:a b c “Satellite Navigation – Ground Based Augmentation System (GBAS)” . Www.faa.gov . Retrieved 2016-05-19 .
  3. Jump up^ http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/howitworks/
  4. Jump up^ http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/mobileAll/GBAS_Newark.pdf
  5. Jump up^ http://www.fly2houston.com/0/3921086/0/83280/
  6. Jump up^ RTCA DO-245A Table 2-1
  7. Jump up^ “SmartPath Ground-Based Augmentation System” . Aerospace.honeywell.com . Retrieved 2016-05-19 .
  8. ^ Federal Aviation Administration (FAA) (February 27, 2004). “Ground Based Augmentation System (LAAS)” . Retrieved April 5, 2010 .
  9. ^ Department of Transportation and Department of Defense (March 25, 2002). “2008-2012 FAA Flight Plan” (PDF) . Retrieved April 5, 2010 .
  10. IHS Aerospace – Honeywell (July 7, 2005). Honeywell to Update Local Area Augmentation System (LAAS) Prototype. Press Release.

 

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