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Respond to TAWS alerts without delay in an appropriate manner.
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Correlate the results of the navigation accuracy check with the operation of the predictive TAWS functions (e.g. overhead TERR switched to OFF when GPS PRIMARY is lost and NAV mode cannot be continued – applicable only if the automatic TERR deselection has not been activated).
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Chase doubts in ATC communications, especially during approach and landing (e.g. confirmation of radar contact, altimeter settings). Refer to FOBN “Human Performance – Effective Pilot/Controller Communications” (See AIRBUS References).
4.3. REGULATIONS FOR TAWS
The carriage of TAWS with forward-looking terrain avoidance function (i.e. predictive functions) is mandatory in all ICAO member States as per ICAO Annex 6 – Operation of Aircraft – Part I:
“6.15.2 All turbine-engined aeroplanes of a maximum certificated take-off mass in excess of 15 000 kg or authorized to carry more than 30 passengers shall be equipped with a ground proximity warning system which has a forward looking terrain avoidance function.”
As per EASA EU OPS 1.665:
- TAWS with a predictive terrain hazard warning function is mandatory.
As per FAA FAR 121.354:
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TAWS is mandatory for aircraft manufactured after 29 MAR 2002.
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TAWS is mandatory since 29 MAR 2005 for aircraft manufactured on or before 29 MAR 2002.
4.4. MANUFACTURERS FOR TAWS
To fulfill the Terrain Awareness function, AIRBUS proposes the following two systems: the Honeywell EGPWS and the ACSS T2CAS, available at the time of writing the brochure.
TAWS CP ND
Figure 4-26 provides a simplified view of the TAWS architecture.
* Refer to 4.1.4 – Introduction of GPS Position into TAWS Architecture for details.
4.4.1. HONEYWELL EGPWS
The Honeywell GPWS was the first system to be certified on AIRBUS aircraft in early 1990s. The Honeywell EGPWS was the first system capable of predictive functions to be certified on AIRBUS aircraft in late 1990s on A300/A310/A320/A330/A340 aircraft.
More information is available at http://www.honeywell.com/sites/aero/Egpws-Home.htm.
4.4.2. ACSS T2CAS
The ACSS T2CAS includes a TAWS module capable of predictive functions. It was certified in 2004 on AIRBUS aircraft.
As the name indicates, the T2CAS encompasses two functions (traffic awareness and terrain awareness) into the same Line Replaceable Unit (LRU). In terms of architecture, the T2CAS LRU is inserted into the ACAS LRU (e.g. TCAS 2000) and EGPWS wirings are directly connected to the T2CAS (refer to Figure 4-28).
The advantages of T2CAS are less weight, simplified maintenance, less wiring, less sparing.
More information is available at http://www.acssonboard.com/products/t2cas/.
4.4.3. TAWS MODULE OF ACSS T3CAS
The ACSS T3CAS is a further step of integration including:
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