24/25 september 2002atn2002 (london)1 delivering cns/atm services to the aircraft presented by...

24/25 September 2002 ATN2002 (London) 1

Delivering CNS/ATM Services to the Aircraft

Presented by Forrest Colliver

A discussion of the FANS/ATN accommodation question, in the context of ground Air Traffic Service provider

communication architectures


The CNS/ATM Deployment Problem Statement (1 of 2)

Deploying CNS/ATM…what we’d like… We all implement CNS/ATM the same way… at the same pace… based on “master plan”, standardized on a global basis.

The reality… Regional stakeholders implement pieces of the CNS/ATM

puzzle based on local political & industrial priorities; using available technologies & tailored operational

procedures; on an ad hoc basis.

Meanwhile, ICAO, IATA, et. al. create the “real” CNS/ATM international operational service & technology standards; broad user consensus and on longer-term benefits models


The CNS/ATM DeploymentProblem Statement (2 of 2)

The result… Competing non-interoperable CNS/ATM technologies &

services Costly & inefficient process for stakeholders & vendors Compromised long-term CNS/ATM benefits No obvious growth path And of course…a lot of shouting… !


Data Link Implementation… the Status Quo

ATN : the ICAO, EUROCAE & RTCA standard for CNS/ATMEuropean & US trials from 1992+; operational deployment in US from 2003-2005; planning in progress in EuropeCPDLC is the benefits driver, based on positive business cases (C/AFT, RTCA, EUROCONTROL) plus user demandUses modern data links (VDL, SATCOM, ATM, IP etc.), thus integrity & performance suitable for high density airspaces

Point-to-Point Data Link Services

Trials in Europe & US from 1995+ have matured a variety of broadcast link technologies (VDL4; Mode S, UAT)Main user of broadcast data links remains surveillance applications based on ADS-B: from basic air/ground surveillance to autonomous aircraft surveillance systemsBroadcast media optimized for surveillance, not “data link”

Broadcast Data Link Services

FANS 1/A: de-facto oceanic data link standardPacific region trials from 1993+; first operational use from 1998+ (for routes in remote/oceanic airspaces)Services include FANS versions of ADS & CPDLCUses ACARS/AIRCOM as data link; performance and integrity acceptable in non-dense airspaces

Oceanic Data Link Services


The point-to-point data link problem in focus…

FANS 1/A & ATN look fairly similar on the surface… Both are point-to-point

sessions between controller, pilot and automated equipment Both support similar applications

context management, ADS & controller/pilot communication dialogs

However… FANS 1/A constrained by ACARS/AIRCOM and legacy architectures

Result: performance and application limitations ATN designed for digital data links & future CNS/ATM architectures

Result: fit for ICAO CNS/ATM purpose with architectural growth potential

Although significant application & performance differences exist between FANS & ATN, strong motivation for “accommodation” of FANS-equipped aircraft in ATN airspace exists, to better amortize FANS investments in these aircraft to-date.


FANS “Accommodation” Scenarios and Consequences (1

of 4)FANS accommodation issues thoroughly studied… by ICAO, IATA, IRRF & other industry groups

The conclusions, unchanged since 1995 ICAO analysis:1. Current FANS 1/A airborne systems cannot be accommodated

transparently in an ATN (EUROCAE ED-110) airspace implementing profile-changing messages without some form of operational workaround (procedural, voice read-back, etc.)

2. If FANS 1/A & ATN aircraft share ATN airspace without workarounds or upgrades: ATN services must be limited to those common with current FANS 1/A Profile-changing messages must be excluded Ground gateways or multi-protocol ground hosts will be required

In the case of FANS accommodation in dense/continental ATN airspace, ICAO CNS/ATM data link benefits will necessarily be constrained.


FANS “Accommodation” Scenarios and Consequences (2 of

4)

However, given that “FANS accommodation” transparent to the Air Traffic Service provider is

not viable, but that the coexistence of FANS & ATN aircraft in the same airspace is required, what are

the available communication architectural choices ?


FANS “Accommodation” Scenarios and Consequences (3

of 4)

External Gateways External to the CNS/ATM provider perimeter & control Likely operated by communication service provider, like

store & forward message switch, performing FANS/ATN application conversion

Internal Gateways Internal to the CNS/ATM provider perimeter & control Likely operated by ATS provider, performing mainly protocol

conversionMulti-Protocol CNS/ATM Host

Implemented within CNS/ATM provider perimeter & control Part of ATS provider ATM host system; includes both

application & communication functions; preserves end-to-end service relationships with no intermediate translation functions


FANS “Accommodation” Scenarios and Consequences (4 of

4)

Characteristic External Gateway

Internal Gateway Multi-Protocol Host

Acquisition Cost Relatively high per gateway(due to technical

complexity and certification issues)

Medium per gateway(similar to External, but with reduced technical

complexity)

Relatively low(integrated/optimized for

host)

Lifecycle Cost High(limited control over operating costs and

network tariffs)

High(limited control over operating costs and

network tariffs)

Medium to Low(better control over

operating costs and network tariffs)

Technical Complexity High(completely generic)

Medium(partly optimized for ATS

center needs)

Low(fully optimized for ATS

center needs)

Performance Relatively lower(due to complex

functionality & sessions per aircraft)

Medium(partly optimized for ATS

center needs)

Relatively higher(fully optimized for ATS

center needs)

Security Issues Significant(due to scope of control and

technical complexity)

Moderate(partly optimized for ATS

center needs)

Low(optimized for ATS center needs; operated by ATS

authority)

Liability & Certification Complexity

High(due to application gateway role in end-to-end services)

Medium(due to design assurance

requirements)

Low(based on integration with ATS host system & center)

Maintains ATN Baseline 1 Service Benefits

No(due to conversion of FANS

to ATN application messages)

Possible(depends on “application” nature, or not, of gateway)

Yes(maintains separate

ATN/FANS end-to-end thread)


Ground Data Link Architecture

Basic ATN

ATNG/G BIS

Local ATNG/G BIS

ATNA/G BIS

WAN(X.25, IP, FR, …)

ATCC

Local ATNG/G BIS

ATCC

ATNG/G BIS

ATSO

ATNA/G BIS

ATNA/G BIS

ATN ES/BIS

CSP





General ATN Backbone Extension

ATNG/G BIS

ATNG/G BIS

ATSO

CSP

ATNG/G BIS

ATSO

BackboneBIS

Backbone BIS

Backbone BISWAN

(X.25, IP, FR, …)

WAN(X.25, IP, FR, …)ATN

A/G BIS


ATN ES/BIS

To other domains…

To network management systems



FANS Accommodation using Gateways

ATNG/G BIS

ATNG/G BIS

ATNA/G BIS

WAN

WAN

ATCC

ATNG/G BIS

ATS

WAN

CSP

FANS ATNGTW

FANSaccess

ACARSNetwork

ATNG/G BIS

ATCC

FANS ATNGTW

Internal

External

ATNFANS 1/A



Multi-Protocol Host

FDPSSDPSHMI

VDL 4

VDL Mode 4Stations

NationalNetworks

UAT

Mode S‘ ExtendedSquitter ’Mode S

Radarnet

Mode S

CAERAFCTS

Satcom

ATN

ATN ES

Aircraft data

VDL Mode 2

MeteoData

ATIS

Meteo Access

VHF Satcom

ACARS NetworksSITA-ARINC

CPDLCADS

FANS-1

ATCC Access



ATN Design Tradeoffs

ATS Service Providers

End-Systems Only

End-Systems and ATN Routers Only

End-Systems, ATN Routers and some Subnetworks

End-Systems, ATN Routers and most Subnetworks

Communication Service Providers

Full ATN Internet Service

Partial ATN Internet Service&/or Subnetwork Service

Most Ground-Ground Subnetwork & Air-Ground Subnetwork Service

Some Ground-Ground Subnetwork & Air-Ground Subnetwork Service

Incre

ase

cap

ital in

vestm

en

tD

ecre

ase

ATS o

pera

ting co

stsIn

crease

ATS co

ntro

l of co

mm

unica

tions

Balance between ATS providers and Communication Service providers to provide ATN

service interfaces


Conclusions Numerous analyses have shown that current FANS 1/A

aircraft cannot be accommodated transparently in ATN Baseline 1 airspace, without loss of benefits available to ATN aircraft.

However, FANS 1/A aircraft may be able to obtain benefits in mixed airspaces without comprising services to ATN aircraft, if ATS providers communicate to each aircraft type directly.

This approach eliminates the viability of the “external gateway”, but can be supported by the internal gateway, if properly implemented and operated.

The best ground architecture for FANS accommodation is the multi-protocol ATS host:

Since FANS and ATN aircraft can be clearly distinguished for air traffic management and communication purposes, and,

Since ATS services can be tailored to local needs.

24/25 september 2002atn2002 (london)1 delivering cns/atm services to the aircraft presented by...

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