o The deployment of Controller Pilot Data Link Communication (CPDLC) reduces the amount of information available in the party line.
o The visual scans are limited in front of and above the own aircraft.
o The visual scans provide a rough estimate of the range, the relative altitude, and the vertical tendency.
o Instrument Meteorological Conditions (IMC) limit the visual scans.
ATSAW AIRB improves the construction of traffic awareness as:
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It detects all aircraft capable of ADS-B OUT around the own aircraft.
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It is more precise than visual scans for the location of surrounding aircraft.
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It does not depend of the meteorological conditions.
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It reduces the mental effort of the flight crew to construct the traffic picture.
3.6.2.2.2. Visual Acquisition for See-and-Avoid
The See-and-Avoid procedure mainly relies on the visual acquisition of surrounding aircraft. However, the flight crew hardly achieves the visual acquisition of an aircraft because:
o Aircraft that fly VFR are often small, and aircraft that fly IFR are bigger but faster.
o An aircraft on a collision course remains on a constant bearing. The flight crew hardly detects the threat due to the lack of apparent relative movement.
o In busy flight phases (e.g. approach), the flight crew may inadvertently reduce the time for visual scans due to the workload increase.
o The windshield limits the visual scans. Some dead angles appear in specific aircraft attitude (e.g. during a turn).
o The flight crew may wrongly identify an aircraft through visual scans.
ATSAW AIRB improves the visual acquisition for See-and-Avoid as:
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It provides a precise location of surrounding aircraft.
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It provides the flight number (when available) of each aircraft.
3.6.2.2.3. Traffic Information Broadcasts by Aircraft (TIBA)
The Traffic Information Broadcasts by Aircraft (TIBA) is applied in areas where:
- Radar surveillance is low or absent, or
- Communications are not reliable, or
- Air Traffic Services are not reliable.
The TIBA objective is the collision avoidance instead of separation provision. Therefore, in TIBA airspaces, a flight crew may perform a collision avoidance maneuver based on TIBA reports listened on the radio frequency. In this context, the flight crew makes again a significant mental effort to construct the traffic picture. In addition, in TIBA airspaces, it is for collision avoidance purposes. Refer to Attachment C of ICAO Annex 11 (see References) for details about the TIBA procedure.
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