R' Rawlings

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An Historical Perspective
Area Navigation

• R. Rawlings
• Airspace Management and Navigation Unit
• EUROCONTROL Agency

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OVERVIEW

• Development of RNAV
• B-RNAV Implementation
• Limitations
• Where Now

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STARTING POINT

• Where do we start?
• VOR Movers
• DECCA Navigator eg OMNITRACK etc 1960s
• Starting point for systems we today call RNAV
• Late 60s early 70s -
• Early digital RNAV using VOR/DME navigation

Potential benefits of RNAV systems have long been
appreciated but only slowly realised .
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TOWARDS THE FMS

• 70-80s emphasis placed on FMS - economy of
  operation etc.
• 1971 Decca Ambac MONA FMS system certified for
  carriage on L1011
• VOR/DME RNAV at start
• mid 70s - DME/DME
• 1980 DME/DME accuracy shown better than 0.5NM.
• Phased implementation for RNAV in en-route and
  terminal area recommended. Eventual use of
  4D-RNAV anticipated.
• 1983 EUROCONTROL analysis of 12000 en-route
  tracks show standard deviation of 0.4NM.

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POST 1980s

• FMS has become standard fit on modern aircraft
• But
• ATC could not provide special service for limited
  subset of aircraft - reduces capacity
• routes remained oriented to ground navaids
• optimum profiles (FMS) constrained by need to
  maximize airspace capacity
• Expected gains therefore not realised

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RESULT

• Pressure from operators who equipped with RNAV
• Options reviewed in late 1980s
• Considered status and future development
  capabilities
• Considered 1998 as a target date for RNAV
  application

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EQUIPAGE FORECASTS
1986 estimates
100
by operators for
ALL Area NAV
P-RNAV (1986 Estimates)
80
FMS 1986 Est.
60
Area NAV (1981 IATA Est.)
40
FMS (1981 IATA Est.)
20
1986 Estimate
4D FMS
0
1980
1990
2000
Year
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ECAC MINISTERS DECISIONS

• The two ECAC Strategies for the 1990s, adopted
  in April 1990 and March 1992 respectively,
  required that
• the carriage of RNAV equipment will become
  mandatory in all en-route airspace by 1 January
  1998.
• States are to make available RNAV based
  procedures for IFR operations in Terminal areas.

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PREPARATION

• BASIS ECAC Strategy for 90s
• ICAO FEATS Strategy
• FEATS -P-RNAV the norm in the first half of the
  period of application (1995-2005)
• AIC issued by EUROCONTROL in 1991
• Precision RNAV (P-RNAV) required above FL 290
• Basic RNAV (B-RNAV) required in designated
  airspace below 290
• RNAV Standard developed by EUROCONTROL -
  published 1993

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B-RNAV Implemented

• 1995 AIC
• With effect from 1998, the carriage of B-RNAV
  equipment approved for RNP 5 operations will
  become mandatory on the entire ATS Route Network
  in the ECAC area including designated feeder
  routes (SIDs STARs) in/out of notified TMAs.

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WHY B-RNAV ?

• EUROCONTROL instituted a review of RNAV policy
• aircraft equipage slower than predicted
  (practically no retrofit had occurred)
• benefit to cost ratio of P-RNAV remained positive
  but was much smaller than expected.
• benefits to be derived from B-RNAV were
  themselves significant and sufficient to warrant
  a B-RNAV mandate,
• achieving capacity gains would require a uniform
  application on all ATS routes and link/feeder
  routes.

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B-RNAV EQUIPPAGE

• Ground infrastructure (VOR/DME) remains
• non-RNAV reversion possible
• Not proposed for Terminal Operations
• Therefore simplified requirements
• lower integrity/continuity/functionality
• no data base required
• enabled significant proportion of aircraft to
  meet requirement with existing equipment, allowed
  simpler GPS based systems

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B-RNAV LIMITATIONS

• Limited applicability to TMA
• workload
• wide variation in track performance on procedures
• integrity
• BUT
• Many aircraft equipped with systems better than
  minimum

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B-RNAV RESULTS

• Greater flexibility to airspace designers -
  routes no longer have to be defined by navaid
  locations.
• Additional routes possible
• Structural changes support increased airspace
  capacity
• Revised route structure gives reduced track
  miles.
• Impact on aircraft equipage kept to a minimum.

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EXAMPLE
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BEYOND INITIAL B-RNAV IMPLEMENTATION

• Uniform application for all en-route Flight
  Levels and - where needed - on feeder routes
  to/from TMAs
• Aims of FEATS Strategy met even though P-RNAV not
  required
• Need to consider longer term developments post
  B-RNAV
• Navigation Strategy developed - covers period to
  2015 and beyond

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FREE ROUTES PROJECT

• NEXT STEP FOR EN-ROUTE RNAV APPLICATION
• Remove need for fixed RNAV Routes in upper
  airspace
• 8-States Project, Civil and Military
• (Belgium, Denmark, Finland, Germany,
  Luxembourg, Netherlands, Norway, Sweden and
  Eurocontrol)
• provides
• Increased capacity
• Reduced cost
• More flexibility
• No additional airborne equipment (B-RNAV)
• Phased Implementation extend ultimately to whole
  ECAC

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TMA RNAV

• Pressure to use RNAV in TMA
• Need to link Airport with RNAV en-route
• RNAV routes offer potential for improved
  efficiency
• environmental impact
• Implementations have started to occur
• Initially B-RNAV with operational restrictions
• now P-RNAV using the new JAA material

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OBSERVATIONS

• Some initial implementations gave poor track
  consistency
• large variation in RNAV procedure application
• RNAV limitations not always appreciated in the
  design of procedures
• To develop a consistent and safe ECAC wide
  application - Terminal Airspace RNAV Application
  (TARA) Task force established

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Performance Variation
Performance differences observed during
EUROCONTROL Studies in early 90s
OM16
DALIK
DC10
B737
B737
B737
B737
SID
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TMA RNAV DEVELOPMENTS

• Initial work directed to providing greatest
  applicability to existing equipment
• EUROCONTROL RNAV Procedure Design Guidelines
  published 1998
• JAA TGL for P-RNAV published in November 2000

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Precision RNAV (P-RNAV)

• RNP 1 accuracy
• Aim to enable majority of FMS/RNAV meet standard.
• Early application of RNAV meeting RNP 1 accuracy

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RNP (x) RNAV

• MASPS for RNP (x) RNAV developed jointly by RTCA
  and EUROCAE
• Aim
• RNAV capable of meeting RNP requirements
• Integrity
• Functionality
• etc.

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THE FUTURE

• RNAV applications developing rapidly -
  criticality of operations increase
• En-route
• TMA
• Approach
• Need to ensure that RNAV developments can provide
  the environment in which RNAV applications can be
  safe, efficient and cost effective.

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IMPLICATIONS

• Need to consider the implications of the proposed
  RNAV applications
• Operators - decisions about re-equipment
• ATS providers - preparations for changes to
  airspace and operations
• Data providers - quality of co-ordinate data
• Airspace planners/procedure designers -RNAV
  capability and limitations
• etc

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