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Difference between revisions of "WAAS Performances"

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==WAAS Performances==
 
==WAAS Performances==
  
Satellite Based Augmentation Systems ([[SBAS General Introduction|SBAS]]) performances are usually described in terms of accuracy, integrity, availability and continuity. The WAAS specification performance requirements<ref name="WAAS SPEC">[http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/documents/media/waas/2892bC2a.pdf ''Specification for the Wide Area Augmentation System (WAAS)''], FAA-E- 2892b, August 13, 2001, [http://www.faa.org FAA].</ref> depend on the phase of the flight: 1) en route through non-precision approach (NPA) and 2) precision approach.
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Satellite Based Augmentation Systems ([[SBAS General Introduction|SBAS]]) performances are usually described in terms of [[Integrity|integrity]], [[Accuracy|accuracy]], [[Availability|availability]], and [[Continuity|continuity]]. The WAAS specification performance requirements<ref name="WAAS SPEC">[http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/documents/media/waas/2892bC2a.pdf ''Specification for the Wide Area Augmentation System (WAAS)''], FAA-E- 2892b, August 13, 2001, [http://www.faa.org FAA].</ref> depend on the phase of the flight: 1) en route through non-precision approach (NPA) and 2) precision approach.
  
 
According to its specification document, WAAS performance requirements are the following:<ref name="WAAS SPEC"/>
 
According to its specification document, WAAS performance requirements are the following:<ref name="WAAS SPEC"/>

Revision as of 07:35, 18 October 2011


WAASWAAS
Title WAAS Performances
Author(s) GMV.
Level Basic
Year of Publication 2011
Logo GMV.png


The Wide Area Augmentation System (WAAS) is the United States Satellite Based Augmentation System. The programme, started in 1992, is being carried out by the Federal Aviation Agency (FAA)[1] and is specially developed for the civil aviation community.[2] The system, which was declared operational in late 2003,[3] currently supports thousands of aircraft instrument approaches in more than one thousand airports in USA and Canada.[4] WAAS service area includes CONUS, Alaska, Canada and Mexico.[5] The WAAS programme is continuously in evolution; two development phases have been already covered, a third is in progress, and there are plans to improve the capability of the system in parallel with the evolution of the SBAS standards towards a dual-frequency augmentation service.[6]


WAAS Performances

Satellite Based Augmentation Systems (SBAS) performances are usually described in terms of integrity, accuracy, availability, and continuity. The WAAS specification performance requirements[7] depend on the phase of the flight: 1) en route through non-precision approach (NPA) and 2) precision approach.

According to its specification document, WAAS performance requirements are the following:[7]

1. WAAS Performance Requirements for En Route through 'Non-Precision Approach'
Performances Requirements for En Route through Non-Precision Approach
Performance Requirement Total System Navigation System WAAS Signal-in-Space Airborne
Availability 0.99999 0.99999 0.99999 N/S
Accuracy
95% Horizontal Position
99.999% Horizontal Position
95% Vertical Position
95% Pseudorange

N/S
N/S
N/A
N/A

100 m
500 m
N/A
N/S

N/S
N/S
N/A
N/S

N/S
N/S
N/A
1.2 m
Integrity
Integrity Risk
Time-to-Alarm

N/S
10 s

N/S
10 s

10-7/hour
8 s

N/S
2 s
Continuity
Continuity of Navigation
Continuity of Fault Detection (1)

1 - 10-5/hour
1 - (2x10-5)/hour

1 - 10-5/hour
1 - (2x10-5)/hour

1 - 10-8/hour
1 - 10-5/hour

1 - 10-5/hour
1 - 10-5/hour


(1) Excluding outages of less than 5 minutes.
2. WAAS Performance Requirements for Precision Approach
Performances Requirements for Precision Approach
Performance Requirement Total System Navigation System GPS/WAAS Signal-in-Space Airborne
Availability N/S N/S 0.999 N/S
Accuracy
95% Horizontal Position
95% Vertical Position
95% Pseudorange

33.5 m
9.8 m
N/A

7.6 m
7.6 m
N/S

N/S
N/S
N/S

N/S
N/S
1.2 m
Integrity
Integrity Risk
Time-to-Alarm

N/S
N/S

N/S
N/S

10-7/approach
5.2 s

N/S
N/S
Continuity
Continuity of Navigation
Continuity of Fault Detection
1 - 10-4/approach
N/S
N/S
1 - 10-4/approach
N/S
N/S
1 - (5.5x10-5)/approach
N/S
N/S
1 - (4.5x10-5)/approach
N/S
N/S
N/S stands for Not Specified.
N/A stands for Not Applicable.

On July 10, 2003, the WAAS system was certified for for safety-of-life aviation, covering 95% of the United States, and portions of Alaska [3][8]. At present, WAAS supports en-route, terminal and approach operations down to a full LPV-200 (CAT-I like Approach Capability) for the CONUS, Mexico and Canada. Typical performances provided by WAAS System when considering operating in LPV (Horizontal Alarm Limit = 40 m , Vertical Alarm Limit =50 m) are shown in next figure:[9]

Typical WAAS LPV Coverage

Notes

References