Overview of RAIM

Air Traffic Management Engineering Officer ATMC, MLIT

Instructor Training on New CNS/ATM Systems Training “ATFM, GNSS Specialized Course”

Nov. 11, Fukuoka

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Contents

PBN

GNSS

RAIM

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PBN

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Area Navigation

Area Navigation

A method of navigation which permits aircraft operation on any desired flight path within the coverage of ground or space-based navigation aids or within the limits of the capability of self-contained aids, or a combination of these.

conventional navigation area navigation

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PBN concept

PBN Concept

◊ The PBN concept specifies that aircraft RNAV or RNP system performance requirements be defined in terms of accuracy, integrity, continuity.

◊ The PBN concept represents a shift from sensor-based to PBN.

PBN relies on the use of area navigation and comprises three components.

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PBN and sensor-based navigation

PBN: Performance Based Navigation

Area navigation based on performance requirements for aircraft operating along an ATS route, on an instrument approach procedure or in a designated airspace.

Sensor-Based Navigation

Area navigation not based on performance requirements for aircraft operating.

e.g.

DME/DME RNAV

GNSS(GPS) RNAV

GBAS Approach ･･･

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Navigation specification

Navigation specification

A set of aircraft and aircrew requirements needed to support

Performance-based Navigation operations within a defined airspace. There are two kinds of navigation specification.

◊ RNAV specification

A navigation specification based on area navigation that does not include the requirement for on-board performance monitoring and alerting.

◊ RNP specification

A navigation specification based on area navigation that includes the requirement for on-board performance monitoring and alerting.

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No requirement for on-board performance monitoring and alerting

RNAV 10

RNAV specifications

Navigation specification designations

Navigation specifications

Includes a requirement for on-board performance monitoring and alerting

RNP specifications

Oceanic

RNAV 5

En-route

RNAV 1

SID/STAR

RNP 4

Oceanic

RNP 1

SID/STAR

RNP APCH

RNP AR APCH

Approach

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Application of RNAV and RNP specification by flight phase

En-route

RNAV5

Arrival

RNAV1, RNP1

Departure

RNAV1, RNP1

Approach

RNAV(GNSS)

RNP, RNP-AR

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GNSS

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SBAS GPS

(USA)

GLONASS (Russia)

Galileo (Europe)

WAAS (USA)

EGNOS (Europe)

MSAS (Japan)

Positioning system

Augmentation system

GNSS

GNSS elements

GNSS: Global Navigation Satellite System SBAS: Satellite Based Augmentation System GBAS: Grand Based Augmentation System ABAS: Aircraft Based Augmentation System

GBAS ABAS

WAAS (USA)

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GPS

（FAA HP）

GPS (Global Positioning System) Satellite

Altitude: 20,200 ㎞

Period : 11 hours and 58 minites

24 satellites basically

• 4 satellites each in 6 orbits

• 31 satellites (as of Nov. 11)

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Orbit information error

Troposphere

Ionosphere Ionospheric delay（～100m） depend on frequency

Tropospheric delay（～20m）

Multi-pass

Satellite clock error

Altitude 250～400km

Altitude ～7km

Sunbeam

Error factor of the GPS

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Necessity of augmentation system

ICAO GNSS Manual

The existing core satellite constellations were not designed to meet civil aviation performance requirements.

Their signals require augmentation in the form of ABAS, GBAS or SBAS as prescribed in Annex 10.

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Signal-in-space requirements

ICAO SARPs Annex 10 (Aeronautical Telecommunications)

◊ Accuracy (horizontal, vertical), Integrity, Time-to-alert

Continuity, Availability

◊ Horizontal alert limit

• Oceanic 4 NM

• En-route 2 NM

• Terminal 1 NM

• Non-precision 0.3NM approach

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RAIM

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Overview of ABAS

ABAS (Aircraft-Based Augmentation System)

◊ ABAS is an avionics implementation that processes core constellation signals with information available on board the aircraft.

◊ ABAS provides integrity monitoring using redundant range measurements to support fault detection (FD) or fault detection and exclusion (FDE).

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Overview of ABAS

Functions

◊ Classes of integrity monitoring

• Receiver Autonomous Integrity Monitoring (RAIM) – Uses GNSS information exclusively

• Aircraft Autonomous Integrity Monitoring (AAIM) – Uses information from additional on-board sensors

such as IRS and barometric altimeters

◊ Availability aiding for the position solution

◊ Accuracy aiding through estimation of remaining errors in determined ranges

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Necessity of RAIM prediction

ABAS availability

◊ RAIM levels are required for RNAV/RNP (RNAV 5, RNAV 2, RNAV 1 and RNP APCH) and can be verified either through NOTAMs (where available) or through prediction services.

◊ RAIM availability prediction should take into account the latest GPS constellation NOTAMs and avionics model.

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Necessity of RAIM prediction

ABAS availability

◊ The service may be provided by the ANSP, avionics manufacturer, other entities or through an airborne receiver RAIM prediction capability.

◊ In the event of a predicted, continuous loss of appropriate level of fault detection of more than five minutes for any part of the RNAV/RNP operation, the flight planning should be revised.

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Selective Function for RAIM Prediction

SA (Selective Availability)

◊ SA is an intentional degradation of GPS accuracy.

◊ The U.S government discontinued its use of SA in order to make GPS more responsive to civil and commercial users worldwide.

Baro-Aiding (Barometric Aiding)

◊ Baro-Aiding augments GPS signal with altitude and can

also help to increase availability when there are enough

visible satellites.

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Mask Angle

◊ The elevation angle from the horizon below which a receiver is unable to track satellites.

◊ Lower mask angle receiver has small non available area for GPS use.

FD (Fault Detection) / FDE (Fault Detection and Exclusion)

◊ FD requires at least 5 satellites with good geometry to detect a faulty signal.

◊ FDE requires 6 satellites.

Selective Function for RAIM Prediction

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How create the RAIM NOTAM?

CNS coordinator

RAIM NOTAM

Predict RAIM availability

ATMC

MSV-10

GPS

GPS condition and maintenance plan

US COAST GUARD

(02087/11 NOTAMR 0198/11

Q)RJJJ/QGAXX/I/NBO/A/000/999/4146N14049E005

A)RJCH B)1104011452 C)1104041500

E)GPS RAIM OUTAGES PREDICTED FOR APCH

AS FLW

1104011810/1104011820

1104020005/1104020020)

Aircraft operators

AISC

Request

NOTAM issuance

Aeronautical Information Officer

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Prediction Result （sample）

RAIM CONDITIONs

legend

MSAS CONDITIONs (MTSAT-1R)

legend

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ANCHORAGE FIR

PETROPAVLOVSK-

KAMCHATSKY FIR

YUZHNO-

SAKHALINSK

FIR

OAKLAND FIR

PYONGYANG

FIR

VLADIVOSTOK FIR

INCHEON

FIR

MANILA FIR

SHANGHAI

FIR

TAIPEI FIR

FUKUOKA FIR

FUKUOKA FIR

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RAIM NOTAM(Example)

Thank you for your attention