In TIBA airspaces, the flight crew considers there is a collision risk when another aircraft is:
o  At the same flight level or is going to climb/descent through the flight level of the own aircraft

o  Converging on the same route or estimating to pass a point at almost the same time as the own aircraft.

ATSA AIRB improves the TIBA procedure as:
o  It reduces the mental effort of the flight crew to construct the traffic picture.

o  It permits the flight crew to anticipate any maneuvers for collision avoidance.

o  Some flight crews do not broadcast traffic information on the TIBA frequency.

3.6.2.3. IN CRUISE: ATSA IN TRAIL PROCEDURE (ATSA ITP)
ATSA ITP is the use of ATSAW with the In Trail Procedure (ITP). The ITP enables aircraft in oceanic and remote non-radar airspaces to change flight levels on a more frequent basis. The benefits of the ITP are:
.  
A reduction of the fuel consumption by flying the optimum cruise flight level

.  
A reduction of emissions by burning less fuel

.  
An improvement of the flight efficiency by flying flight levels with more favorable winds

.  
An improvement of the flight safety by avoiding flight levels with turbulence

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An increase of the airspace capacity by musical chair sequence: an ITP aircraft leaving its initial flight level leaves a space for another aircraft.

ATSAW significantly improves the traffic awareness of the flight crew. When the flight crew applies the ITP with ATSAW, the ATC controller may authorize the flight crew to climb or descent with temporarily reduced minima of longitudinal separations in predefined circumstances. Therefore, thanks to the reduced longitudinal separation minima, flight level changes should be more frequent.
Note: The ATC controller authorizes reduced longitudinal separation minima during the climb or descent only. The ATC controller re-establishes procedural longitudinal separation minima when the aircraft reaches the new flight level.
The use of ATSAW with the In Trail Procedure is fully described in
Appendix C – ATSAW In Trail Procedure (ITP).
3.6.2.4.  DURING APPROACH: ATSA VISUAL SEPARATION ON APPROACH (ATSA VSA)
ATSA VSA (also called Enhanced Visual Separation on Approach) is the use of ATSAW with the Visual Separation on Approach (VSA) procedure. The VSA procedure permits the flight crew to maintain a visual separation on the preceding aircraft during the approach when VMC conditions are met. The visual separation is shorter than the standard radar separation. Therefore, the benefits of the VSA procedure are:
.  
An increase of the airport landing capacity thanks to the shorter separations between aircraft. The increase is even more significant for airports that operate closely spaced parallel runways. Indeed, at such airports, the VSA procedure permits to simultaneously use several arrival streams with alternation of landings on parallel runways. When the VSA procedure is suspended, some arrival streams are suspended, and the airport landing capacity is reduced.
　
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