RNAV Systems

Question 1

What are the two approved RNAV systems in Australia?

Answer 1

1. Inertial Navigation System (INS/IRS)
2. Global Navigation Satellite System (GNSS/GPS)

Question 2

Elements of INS/IRS

Answer 2

• contains gyroscopes and accelerometers.
• Measures angular velocity and linear acceleration respectively.
• provides positional data to a Flight Management System or its own internal navigation waypoint database
• It may update its position by using GPS and VOR/ DMEs.

Question 3

INS

Answer 3

Inertial Navigation System

Question 4

IRS

Answer 4

Inertial Reference System

Question 5

Difference between IRS & INS?

Answer 5

IRS uses ring-laser gyroscopes as opposed to ILS’s conventional gyroscopes

Interference between counter-propagating laser beams shifts a standing-wave pattern which is detected as motion.

RLGs initialise faster than conventional gyroscopes

Question 6

GPS uses trilateration from at least ______ satellites.

Answer 6

4

Question 7

How many satellites are required for navigation in aviation?

Answer 7

5.

4, where utilising further equipment to enhance accuracy (e.g. data from pressure altimeter)

Question 8

__________ is a requirement for GPS/GNSS to be used as a primary navigation tool.

Answer 8

Barometric aiding.

Question 9

RAIM

Answer 9

Receiver Autonomous Integrity Monitoring (RAIM)

Question 10

Elements of RAIM

Answer 10

• Performs consistency checks on satellites
• Checks GPS receiver itself
• Alerts pilot if checks fail
• RAIM outages are predictable and available at pre-flight briefing.
• RAIM prediction is available from Pilot briefings on the Airservices website.