GPS and INS theory and operating characteristics (Cont)

T-45C TS INav-02

Introduction to INav and Voice Procedures

FAA has approved U.S. civil operators to use GPS

as a primary navigation means in oceanic airspace

and in some other designated remote airspace

areas

GPS Standard Position Service (SPS) has 100

meters horizontal positioning accuracy with a

GPS Precise Positioning Service (PPS) is limited to

authorized U.S. and allied military, federal government,

and civil users who can satisfy specific U.S. security

requirements. PPS requires use of government

authorized crypto-keys. PPS is highly accurate,

averaging 16 meters

10. Differential GPS is being considered by FAA for

certification as a terminal precision approach system.

At the time of this writing FAA had not approved any

GPS system for precision approaches

NOTE: Differential GPS systems transmit a GPS

signal correction factor that is valid for a local area.

Receiving aircraft process that factor along with their

received GPS signals, which produces the level of

accuracy necessary for precision approaches.

11. At least five GPS satellites are in view at any one

time from any place on earth

12. Improved GPS satellites are being designed and

planned for future launch

13. Receiver Autonomous Integrity Monitoring (RAIM) is

a GPS means of determining when a satellite is

providing corrupted information due to jamming or

other reasons

NOTE: RAIM usage requires additional satellite(s)

to be in view, the exact number depends upon the

particular GPS receiver capability and degree of

RAIM capability to be utilized. The T-45C does not

use RAIM.

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