ASAS issues identified
in the AP23 work
ENRI International Workshop on ATM/CNS
5 & 6 March 2009
By
Jean-Marc Loscos, DSNA

Federal Aviation
Administration

AP23 Overview: Deliverables
Action Plan 23 is a FAA and Eurocontrol common study focused on thelonger term airborne surveillance and ground surveillance
applications.
Five deliverables from AP23:
D1 – General data exchange
D2 – Methodology to prioritize applications for AP23
D3 – Operational Role of Airborne Surveillance in Separating Traffic
D4 – Draft proposal for a second set of ADS-B/ASAS applications
D5 – Airborne separation applications : Issues paper
NOTE: D5 is still under work among AP23 for a delivery in 20092

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Contents
Main points from D5 - ASAS Key Issues
These are mostly the key questions in relation to ASAS:
1. Change to ATCO/Flight Crew role and procedures
2. Compatibility with TCAS
3. Transition towards airborne separation and self-separation
4. Airborne separation minima
5. Regulatory and safety case
6. Implementation and operational benefits

D5 sums up the question and tries to provide sensible answers
or indicates work required to provide solutions

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31. Change to ATCO and Flight crewrole and procedures
Paradigm change: new way of providing separation
with ASEP applications.
Several issues are identified:
The delegation of responsibility must be clear at each moment
In ASEP, a pair of aircraft is treated differently by ATCO and the impact
has to be assessed - especially on the design of ATCO HMI.
The duration of delegation might have an impact on mental picture andon traffic situational awareness.
For ASEP, is it always ATCO initiative or can it be on pilot’s request?

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41. Change to ATCO and Flight crewrole and procedures
The operational procedure must be decomposed in phases inorder to support clear and unambiguous role of actors.
With ASEP, traffic situational awareness is increased in the cockpit ☺…
but possibly decreased on the ground.

Data link can be used extensively.
To inform the “reference aircraft” of the ASEP procedure
To exchange technical data or complex messages
To inform ATC of aircraft intentions during the maneuver - however it isdebatable whether this information should be displayed to the ATCO.

Ground tools to determine the opportunity for the ASEP
procedure are probably required.
Monitoring aids could be proposed for reduction of workload?

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52. Compatibility with TCAS
IAPA Project (EUROCONTROL, 2005) showed that interactions
between ASAS applications and TCAS can occur:
When crossing at less than 5 NM SEP, RA can occur;
When crossing at less than 7 NM SEP, TA can occur.

RAs can become a show stopper
Repetitive RAs as in RVSM early days must be avoided=> ASAS procedure and logic must be designed “TCAS RA proof”

TAs can become annoying too=> Maybe a redesign of TCAS is the best way forward

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63. Transition towards
airborne separation and self-separation
Today

ASPAASEP

SSEP: what transition strategy?

ANSP’s way: identify applications that are locally beneficial and proceedwith gradual introduction of ASAS
Airlines and avionics industry’s way: define an operational concept thatmeets SESAR/NextGen objectives and develop a new system

Changing operational environment
Moving forward step by step can help to build up confidence in the newprocedures and gain experience before the next step.
But moving forward slowly makes it difficult to follow for aircraft
equipment and human actors, and will take time to reach SESAR or
NextGen goals.
Mutual benefits must be assessed to find the best agreement on theimplementation timeline

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4. Airborne separation minima
Can we introduce ASEP application without the determinationof airborne separation minima?
If the separation minima is based on airborne surveillance, is it aircraft
dependant rather than airspace dependant?
Do we need a set of values (3, 6, 9 NM) with respect to aircraftperformance?

If the airborne separation minima are too different fromground separation minima, is it operationally viable?
If Ground SEP >> Airborne SEP
Why not SSEP?
(in oceanic airspace in particular)
If Ground SEP << Airborne SEP
Why delegate separation?
(effectiveness of ASEP in terminal areas?)

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85. Regulatory aspects and safety case
ICAO provisions are sufficient to enable ASEP and SSEP.
The operational procedure must be crystal clear on the delegation ofresponsibility.
Contingency procedures must be developed relying on the airborneside solely. In any event, ATCO cannot recover responsibility if
Ground SEP is not met.

Safety cases are needed.
ANSP must establish a safety case for a given application in a given
airspace
The Regulatory authority will have to approve it for certification.
What will be required for this approval is still unclear.

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96. Implementation and operational benefits
ANSP will choose an AS application adapted to the local
environment.
Cost Benefit Assessment
ATCO and flight crew acceptability cannot be dissociated fromoperational benefits such as safety and flight efficiency.
It is difficult to evaluate benefits brought by ASAS application while ASAS
is one element of a complex ATM system.

Examples of CBA already achieved
NATS evaluated ASEP-ITP/ITF/ITM in North Atlantic airspace(ASSTAR project)
DSNA evaluated ASPA-S&M in Paris TMA(PALOMA and CRISTAL PARIS project)10

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6. Implementation and operational benefits
Operationalbenefits
What are the gains for ASEP-ITPin oceanic comparedtoATSA-ITP?
Only marginal additional benefits with a more complex equipment
However, more additional benefits could be brought by thecombination with other applications such as ASEP-ITF, ASEP-ITM.

DSNA evaluated the airspace design and the need for
mandatory carriage under ASPA-S&M
We can expect benefits without changing the Paris TMA but not much
Workable with partial equipage of the fleet, but no benefits under70% of equipped aircraft

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Conclusions
AP23 team is preparing for the future of AS applications
using NextGen/SESAR concept of operations and setting
the scene at the ICAO level.
The production of D5 on “airborne separation issues” will
provide a high level framework and possibly hints foranswers to the key questions.
ANSP and Airlines will need to assess detailed and specificapplications and conduct CBA before implementation.

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Thank you
Jean-Marc.Loscos@aviation-civile.gouv.fr

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