1. CLASS I Candidate CSs (started by 2006) GENERAL ASM ATFM ATS COM NAV
Reference
CONOPS
(2011)
Software
Assurance
Level
Cross Domain
Information
Sharing
A-CDM
UAV
Systems
Operation
ASM
Flexible Use
Of Airspace
Airspace
Design
ATFM
IFPS
User Manual
Data
Exchange
Format
E-ATFM
(CFMU/IFPS)
ATS
OLDI
Open ATC
Architecture
Model
ATS Middleware
(ACC-ACC only)
Interoperability
Of Flight
Data Processing
A-SMGSC
(Level 1 & 2)
COM
NAV
GBAS
CAT I
Procedures on
Use of GPS
SURV
Surveillance
Data Exchange
AIS
MET
CLASS I Candidate CSs
(started by 2006)

2. CLASS II Candidate CSs (started in 2007) GENERAL ASM ATFM ATS COM NAV
DL Services
over ATN in
Continental Airspace
DL Services
over FANS1/A in
Continental Airspace
DL Services
over ACARS in
Continental Airspace
ATS
A-SMGCS
(Level 3 & higher)
Arrival
Management
Departure
Management
Surveillance
Performance
COM
European AMHS
Profile
Telephone for ATC
purposes
Voice over IP
(ground only)
NAV
SBAS
Galileo, GNSS
SURV
Ground-based
primary radar
equipment
Multilateration
Equipment
Surveillances
Services using
ADS-B
AIS
Generic Data
Process & Principles
Integrity -
Data Origination
Integrity -
Data Publication
MET
Systems & Procedures
For the use of
MET info
CLASS II Candidate CSs
(started in 2007)

3. CLASS III Candidate CSs
GENERAL
Reference
CONOPS
(2020)
ATFM-CDM
ASM
ATFM
Advanced Data
Exchange Formats
ATS
Interfaces
CWP /
Data Processing
Interfaces with
Flight Data
Operator Positions
Interfaces with
Local centre
Sub-systems
Flight Plan
Information
Subscriber Systems
ATS Middleware
(inter & intra ACC)
COM
Directory services
In Support
of AMHS
Voice over IP
(including
air/ground)
NAV
DME ground
equipment
ILS ground
equipment
MLS
GBAS CAT II/III
SURV
AIS
Aeronautical
Information
Exchange (AIXM)
MET
CLASS III Candidate CSs
(started by 2008 or later)

4. CLASS IV Candidate CSs (started on demand) GENERAL ASM ATFM ATS COM
Surveillance
Data Processing
COM
Ground and mobile
AM Stations
( – 137 Mhz)
HF radio
equipment
UHF for use by
Civil ATC
NAV
NDB
Ground equipment
VOR, D-VOR
ground equipment
VHF Marker
Beacon
Ground equipment
SURV
Ground-based
secondary radar
equipment
AIS
CLASS IV Candidate CSs
(started on demand)
MET