ASSTAR User Forum ASAS-TN2 Workshop – 4 April 06 – Rome

ASAS Crossing and Passing Applications in Radar Airspace(operational concept and operational procedure)

Jean-Marc Loscos, Bernard Hasquenoph, Claude ChamayouDSNA

ASSTAR User ForumASSTAR User ForumASAS-TN2 Workshop – 4 April 06 – RomeASAS-TN2 Workshop – 4 April 06 – Rome

OVERVIEWOVERVIEW

Operational concept: airborne separation application

– Visual clearance extrapolation

– Operational applicability in radar airspace

ASAS C&P application in radar airspace

– Applicability conditions

– Phases

– Phraseology

Issues and questions

Operational conceptOperational concept

Airborne separation category according to PO-ASAS classification

– Delegation of responsibility from the controller to the flight crew to execute a crossing manoeuvre with respect to one designated target aircraft.

– The controller remains responsible for the separation with respect to the other aircraft in the sector.

Conditions

– This is post AS/GS package I and ADS-B IN (and data link) would be available.

– Traffic conditions would be similar to current situation for Controller tools.

Related Programmes

– MA-AFAS, MFF, IAPA

Operational applicability in radar airspaceOperational applicability in radar airspace

In a given crossing, separation can be achieved by ATC

– laterally

<1000ft>5Nm


In a given crossing, separation can be achieved by ATC

– vertically

1000ft<5Nm

Visual clearance extrapolationVisual clearance extrapolation

Upon flight crew visual acquisition, the ATCO can clear the aircraft for visual separation.

The flight crew maintains continuous visual contact and notify the ATCO when “Clear of Traffic”.

– The applicability conditions were very constrained, e.g. VMC, convergence of the trajectories, visual range.

– The procedure had to be dropped at high altitudes for safety reasons, i.e. triggering ACAS alerts.

Thanks to ADS-B, visual acquisition would no longer be required, applicability conditions would be relaxed.

The procedure must be designed in such a way NOT to trigger ACAS alerts. IAPA project provides results on range values to ensure compatibility. 5 NM is recommended value for lateral crossing.

ASAS Lateral crossing applicationASAS Lateral crossing application

Description

– To allow a controlled and suitably ASAS equipped aircraft to modify its horizontal trajectory in order to achieve lateral separation by itself (airborne separation) from another converging controlled flight independently of vertical profile.

Expected benefits

– With no change in current ground separation minima, capacity and flight efficiency gains are expected by allowing aircraft to fly more closely to their original flight plan and possibly reducing the number of deviations from flight plan.

Presently, the actual distances for crossing aircraft exceed the applicable separation minima in radar airspace by a large margin. This is because the air traffic controller anticipates and manages his workload by issuing early spacing manoeuvre instructions

– Capacity is declared for a given sector to accommodate ATCO’s workload. If the workload could be reduced, declared capacity could be increased.


Target aircraft

Clearance aircraft

: published way point

Surrounding traffic

XTKmax

TKmax

Maximum track alteration

Sector boundaries


Scenarios : Co-altitude Pass Behind, Co-altitude Pass In Front, Descending Pass Behind and Climbing Pass Behind

Clear of traffic

Suggested TCPs Target aircraft

Clearance aircraft

Offset route

Operational Environment

– The operational environment for this application is envisaged to be radar airspace in Europe.

– Envisioned operational scenarios First scenario: both aircraft fly in the same sector for the duration of the

application. Second scenario : a transition to another sector by one or both aircraft

occurs while the two aircraft perform lateral crossing


59%29%

7%

5%

41%

Horizontal crossing,Vertically separated, Novertical crossing

Fully separated

Horizontally separatedonly

Vertically separated only

Out of 24 hours of flights, 331 encounters were identified among which 41 % (>144) could support ASAS Crossing procedure. This represents in average 3 potential ASAS Procedure per hour per sector.

Count of crossings on actual radar data of 2 Feb 06 traffic on ACC sectors T and W


ASAS C&P Operational PhasesASAS C&P Operational Phases

Set-up Phase

Identification Phase

Clearance Phase

Execution Phase

Termination Phase

Controller

Flight crew

Application phase by phaseApplication phase by phase

Applicability conditions at set-up phase: ATCO Both clearance and target aircraft are appropriately equipped

(ASAS and ADS-B respectively). Aircraft trajectories are appropriate for lateral separation, e.g.

routes are crossing (ICAO definition). The manoeuvre for conflict resolution is contained in an envelope

that the ATCO checks as compatible with surrounding traffic (possibly including the resuming manoeuvre).

Before initiating the application, the ATCO will ensure that the target aircraft adheres to its own route.


Identification phase: ATCO and Flight Crew

– The ATCO transmits the target ID to the flight crew.

– The flight crew confirms the positive identification.

Clearance phase: ATCO and Flight Crew

– The ATCO transmits the clearance for ASAS lateral separation including possible constraints.

– The flight crew acknowledges.


Execution phase: Flight Crew

– The flight crew starts the lateral separation process monitors the separation during the whole process until the system declares

« clear of traffic ».

Termination phase: Flight Crew and ATCO

– The flight crew reports: « clear of traffic ». « resuming navigation », as previously cleared by the ATCO.

– The ATCO issues further clearance as necessary.

Lateral crossing applicationLateral crossing application

Termination conditions

– The clearance aircraft is able to resume safely to its own navigation

– The two aircraft are no longer in conflict.

Phraseology: suggestions for ASAS crossing procedure

ATCO: For ASAS crossing, identify “Target ID”

Clearance: OK, target at 11 o’clock and 55 NM

ATCO: pass behind target, then resuming to WPT .

Clearance: passing behind / [unable to pass behind]

(ATCO: target ID, for information, you are under ASAS crossing) optional

Clearance: Clear of traffic, on course to WPT.

ATCO: Roger.

Issues and questionsIssues and questions Applicability conditions

– Does the controller need assistance?

Acceptability

– By pilots: do both crews need to know the trajectory of the other a/c?

– By controllers: do they need to know the actual deviation?

– Sense of the manoeuvre? (pass in front, pass behind or separate?)

Workload and task sharing

– Monitoring by pilots?

Phraseology

– Number of messages needed?

– Target Aircraft call sign?

Are there other beneficial scenarios?

ASSTAR User Forum ASAS-TN2 Workshop – 4 April 06 – Rome

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