If you wish to contribute or participate in the discussions about articles you are invited to contact the Editor

WAAS Performances

From Navipedia
Revision as of 15:41, 20 June 2011 by Irene.Hidalgo (talk | contribs) (WAAS Performances)
Jump to navigation Jump to search


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


The Wide Area Augmentation System (WAAS) is an GPS Augmentation system developed by the Federal Aviation Administration (FAA), with the goal of improving its accuracy, integrity, and availability. Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.

WAAS Performances

Performances are usually described in terms of accuracy, integrity, availability and continuity. The WAAS specification Performance Requirements[1] are different depending on the phase of the flight: en route through 1) Non-precision approach (NPA) and 2) Precision Approach.

1) WAAS Performance Requirements for Non-Precision Approach are summarized in the following table:

Performances Requirements for Non-Precison Approach
Performance Requirement Total System Navigation System WAAS Signal-in-Space Airborne
Availability 0.999 0.999 0.999 Not Specified (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

10e-7/hour
8 s

N/S
2 s
Continuity
Continuity of Navigation
Continuity of Fault Detection

1 - 10e-5/hour
1 - (2x10e-5)/hour

1 - 10e-5/hour
1 - (2x10e-5)/hour

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

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

2) WAAS Performance Requirements for Precision Approach are summarized in the following table:

Performances Requirements for Precison Approach
Performance Requirement Total System Navigation System WAAS Signal-in-Space Airborne
Availability Not Specified (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

10e-7/approach
5.2 s

N/S
N/S
Continuity of Function
Continuity of Navigation
Continuity of Fault Detection
1 - 10e-4/approach
N/S
N/S
1 - 10e-4/approach
N/S
N/S
1 - (5.5x10e-5)/approach
N/S
N/S
1 - (4.5x10e-5)/approach
N/S
N/S

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:

Typical WAAS LPV Coverage

Notes

References

  1. ^ FAA.Specification for the Wide Area Augmentation System(WAAS). FAA-E- 2892b. August 13, 2001.