k) GNSS and PBN Standards

Question 1

Performance Based Navigation (PBN) encompasses two types of navigation specifications:

Answer 1

RNAV (aRea NAVigation), and
RNP (Required Navigation Performance).

Question 2

What are the differences between RNAV and RNP ?

Answer 2

on-board performance monitoring and alerting is required for RNP but not for RNAV

Both aircraft and flight crew must meet performance standards for that route, which
may change according to the flight phase (en route, approach etc.) and the class of
airspace in which the aircraft is flying.

Question 2

RNAV missed approaches:

Answer 2

Loss of RAIM or RAIM Warning after the IAF – Missed Approach, if the RAIM
Warning then ceases when missed approach is selected you may use the GPS
for missed approach guidance, otherwise you need to use alternate guidance
such as NDB or Dead Reckoning to follow the missed approach procedure.

Answer 3

» RNP 2—en route
» RNP 1—arrivals (SIDs), and (STARs)
» RNP APCH — approach LNAV

Question 4

If in Controlled airspace you must Report RAIM loss of greater than ……….. even if you are receiving positional information for separation standards and if you have a track displacement of more than ………….

Answer 4

• If in Controlled airspace you must Report RAIM loss of greater than 5 minutes even
  if you are receiving positional information for separation standards and if you have a
  track displacement of more than 2 NM.
• When RAIM RESTORED notify ATC for further positional assessment/Assistance.
  When talking with ATC state ‘RAIM FAILURE or RAIM RESTORED

Question 5

Flight Planning

Item 18: G, R , Z

Answer 5

• G is required to indicate GNSS
• R is required to indicate PBN; R requires corresponding entries in Item 18.
• Z on a plan notification means NavGPS/OCEANIC is the sole means of navigation

Question 6

ADS-B

Answer 6

All IFR aircraft in Australia should now (from 2 February 2017) be ADS-B
compliant.

ADS-B is Automatic Dependent Surveillance Broadcast and enables all IFR
aircraft to be accurately tracked by air traffic controllers without the need for
conventional radar. Uses your GPS unit to communicate with ATC.

Question 6

Standard GPS modes:

Answer 6

………………………………………………………..Accuracy……..Full Scale Deflection
RNP2 =……….(en route) >30nm………..2.0nm………..∓5nm
RNP1 =………..(terminal) <30nm………..1.0nm………..∓1.0nm
RNP APCH = FAP/FAF approach………..0.3nm……….∓0.3

Question 7

Procedure for commencing an approach using GPS without entering a holding pattern:

Answer 7

1. In any airspace, the aircraft is tracking to an initial approach waypoint from within the caption region for that waypoint, or
2. In controlled airspace, the aircraft is being radar vectored to intercept the Initial approach segment or is tracking direct to the intermediate fix.

Note: The ‘direct to’ clearances may be requested to the intermediate fix (IF)
provided that the resultant change at the IF does not exceed 45° and the first track
of a GNSS procedure must be joined using the track guidance provided by the
GNSS receiver.

Question 8

Your aircraft is approved for Performance Based Navigation (PBN) which is fitted, and you are qualified
to use. What ATS Flight Notification letter symbol will you use on your flight plan to communicate this to Air
Traffic Control?

Answer 8

Code “R”

Question 9

Your aircraft is approved for PBN operations and you are utilising GNSS RNAV (LNAV) capabilities for
enroute segment of your flight when you notice RAIM is lost for a period of greater than 5 minutes but the GPS is still providing position information. What, (if anything) would be your actions assuming you are in Controlled Airspace?

Answer 9

Five (5) minutes is the limit, after which time ATC must be notified.

Question 10

You are tracking using your GPS for enroute IFR flight and you notice your estimate for the next enroute mandatory reporting point has changed. What is the maximum time difference you can accept before you must notify ATS?

Answer 10

Two (2) minutes.

Question 11

You are about to commence an GNSS RNAV approach, what integrity component of the GPS receiver must be confirmed as “available” before continuing the descent below the LSALT or MSA?

Answer 11

RAIM must be confirmed as available.
This is usually by the unit going into
APP mode prior to the FAF.

Question 12

RNAV Missed Approach

Answer 12

• Loss of Raim or Raim Warning after IAF or below MSA
• If Raim warning cease when missed approach is selected, you may use it for Missed approach guidance , otherwise must use DR or NDB/VOR

Question 13

Vertical Navigation available in AUstralia

Answer 13

• ILS
• Baro - VNAV (accurate barometric altimetry system)

Question 14

GNSS Errors and Limitations
7

Answer 14

• Ephemeris - (3m) old data
• Clock - (3m) clock drift
• Receiver - (1.5m) Noise interference
• Ionospheric - (10m)
• Atmospheric - (3m) water vapour
• Multipath - (3m) signal bounces off terrain
• Selective Availability - (55m) USGPS applied error

Question 14

Quality of GNSS Service
5

Answer 14

• Accuracy - How close (precision)
• Integrity - How much can you trust the info
• Availability - How often system is able to give accurante nav
• Continuity of Service - Work without service outages
• Interference - Affected by things

Question 15

Geometric Dilution of Precision
Give other examples of Dilution of Precision..

High GDOP (Poor Precision) , Low GDOP (Better Precision)

Answer 15

PDOP - Position Dilution of Precision - lat/longitude
TDOP - Time Dilution of Precision - GNSS system time
HDOP - Horizontal Dilution of Precision - loss of precision Horizontal
VDOP - Vertical Dilution of Precision - loss of precision vertical

Question 16

Augmentation System

Answer 16

GBAS - Ground base (3D GNSS aproach (GLS))
SBAS - Satelite Based - WAAS
ABAS - Aicraft Based - mandatory for GNSS - RAIM - FD - 4 satelites if alt connected
……………………………………………………………………………………..FD - 5 satelites ↘ Limits for -2.0nm enroute, 1.0nm term
…………………………………………………………………………………….FDE -6 satelites ↗ RAIM……..- 0.3nm approach

RAIM Loss
Insufficient satelites or GDOP is high
can’t provide integrity to horizontal integrity
Still able to use for enroute Navigation

RAIM Warning - Anomaly detected, no more reliable
Use another means of navigation

Question 17

PBN is able to keep a minimum of navigation accuracy

Answer 17

Surveillance - Use of ADSB and Mode S transponder
Navigation - RNP use Absolute navigation (precisely calculated)
………………….. VOR/NDB use relative navigation , which is unable to provide accuracy to PBN

Question 18

RNAV and RNP specifications

Answer 18

• RNAV - Absolute position, but no requirement for failure, mode error detection and alerting
  Calculate its position 95% of the time. Ex: RNAV1 = calculated its position accurate to within 1nm 95% of time
• RNP - Absolute position and must provide a failure mode and error detection/alerting
  Narrow obstacles and traffic separation
  Calculated its position within … nm 95%, but also ∓2nm 99.999%of the time
  Ex: RNP1: calculated position within 1nm within 95% of time and also ∓2nm containment limit 99.999% of time

Question 19

RNP Navigation Errors

Answer 19

• FTE - Flight Technical Error - ability to fly the required path
• PDE - Path Definition Error - issues with defining precise horizontal/vertical path
• NSE/PEE - Navigation System Error/Position Estimation Error - errors on calculated/actual position
• TSE - Total System Error - sum of all the errors