IREX Flashcards
Which of the following is a component of the user segment of the GNSS system? A) geostationary satellite B) uplink control C) user control station D) GNSS receiver unit
D
Ephemeris refers to:
A) A satellites battery state
B) The frequency of the navigational data messages
C) The calculated position of the satellite in its orbit
D) The C/A code offset uplinked by the master control station
C
A GNSS system is available at all times but is silently delivering navigation solutions which are out by 15 nm most of the time. The system has:
A) low accuracy, poor integrity and low availability
B) low accuracy, low continuity of service but high availability
C) high accuracy, high integrity but low availability
D) high continuity of service, low integrity but high availability
A
Which of the following is not an error in the GNSS system?
A) Clock
B) Ephemeris
C) Atmospheric
D) Night Effect
D
If GNSS Unit uses a widely spaced satellite constellation for the navigation solution, it is likely the position reported by the unit will:
A) have a high GDOP and low accuracy
B) have a low GDOP and high accuracy
C) have a high GDOP and high accuracy
D) have a low GDOP and low accuracy
B
RAIM is an acronym for:
A) Receiver Automatic Integrity Maintenance
B) Receiver Access Intelligent Monitoring
C) Range Activated Input Masking
D) Receiver Autonomous Integrity Monitoring
D
RAIM allows for fault detection (FD) in GNSS System. Which of the following statements is correct?
A) FD requires 5 satellites to be available (4 if barometric aiding is available)
B) FD is a requirement for TS-C129A systems without barometric aiding
C) TSO 145A/146A systems are only capable of less reliable FDE
D) Without FD a GNSS unit is unable to supply position information
A
The en-route horizontal tolerances before a RAIM alert is triggered is: A) 2nm B) 0.3nm C) 1nm D) 1.5nm
A
A GNSS unit doesn’t have sufficient satellite coverage, in this case a TSO 129 or 145/146 receiver will:
A) issue a RAIM loss message and an alternative means of navigation will be required
B) issue a RAIM warning message but the unit can still be used for navigation
C) issue a RAIM loss message but navigation may still be possible
D) issue a RAIM warning and switch off
C
The Airservices RAIM prediction shows there will be a RAIM outage during your flight and FD will not be available for TS-C146A. You were planning to use RNAV (GNSS) for the en-route and approach portion of your flight. Which statement is correct:
A) Your flight is not affected
B) Your flight is not affected as your receiver is TSO-C129 certified
C) FDE and FD will not be available during the period for which the outage is predicted
D) You may not use GNSS at any time during this flight
C
What is the coarse acquisition (C/A) code?
Series of 1’s and 0’s that uniquely identify a satellite
Transmitted from satellite
What is the navigation data message?
Contains current date and time of GNSS
Measure of satellites status and health
Current orbital position of satellite
What degrees must satellite be to minimise received signals?
15 degrees above horizon and in line of site.
What is the masking function used for?
Used to see which satellites will be unsuitable
What are the GNSS errors and limitations?
Ephemeris (3m) Clock (3m) Receiver (1.5m) Ionosphere (1m) and Atmosphere (3m) Multipath (3m) Selective availability (55m)
If satellites are close together, what happens to GDOP, accuracy and precision?
GDOP high
Reduced accuracy
Poor precision
If satellites are spread out, what happens to GDOP, accuracy and precision?
GDOP low
Better accuracy
Better precision
What does RAIM do?
Uses 5 satellites and calculates navigation solutions for each combo of 4 satellites in group. Solutions are compared and if too different then a warning comes up
What are the limits for a RAIM warning for en-route, terminal and 2D approaches?
2nm en-route ops
1nm terminal ops
0.3nm for 2D approaches
If a RAIM alert is displayed, will nav solutions be displayed?
No, not until RAIM is restored
What is barometric aiding and what is it mandatory for?
Altimeter provides non satellite vertical reference if satellites drop from 5 to 4.
Mandatory for TSO C129A
What is FDE and what is is required for?
Fault detection equipment, uses 6 satellites instead of 5, helps exclude faulty satellite.
FDE required for C145A and C146A
What is RAIM outage? When is FDE and FD unavailable unavailable due to this?
When 5 or 6 satellites not visible in the sky.
If only 5, FDE unavailable
If less than 5, FDE and FD unavailable
What can cause a RAIM loss? Can we still use?
If there is insufficient satellites or GDOP is too high.
May still be able to use
When does a RAIM warning occur? Can we still use?
Occur when abnormally is detected in solutions.
No, must use alternate source of navigation, any approach is to be immediately aborted.
Is RAIM required for GNSS operations?
Yes
If you hold a valid instrument rating, what can you do?
Fly IFR and at night under VFR
When must you submit your flight details for an IFR flight?
at least 30 mins before EOBT
What weather do you need for IFR?
Flight or area forecast and aerodrome forecast
(TAF and/or TTF) for destination and alternate including NOTAMs and AIC info
