Appendix B – Example
of an acceptable TAWS installation
ED Decision 2022/008/R
An example of an acceptable installation is a single approved TAWS comprising the following components or inputs:
(a) A single terrain awareness and warning computer.
(b) A single radio altimeter sensor.
(c) A single air data system.
(d) An ILS/GBAS/SBAS/MLS/MMR receiver for Class A TAWS only.
(e) An interface with the landing gear and flaps.
(f) A roll attitude sensor.
(g) An accurate source of aeroplane position e.g. Flight Management System (FMS), or a Global Positioning System (GPS) or both.
(h) Where operations are reliant on the use of QFE, an adequate means of determining the altitude should be provided.
(i) A terrain data base covering the expected region of normal operations, together with a means of updating the stored data and to check its validity (by effective date and geographical region)
(j) A terrain awareness display.
(k) A loudspeaker for voice announcements.
(l) Consideration should be given to presenting voice announcements via headsets at a preset level particularly where active noise-reducing or noise cancelling headsets are used.
(m) Indication of TAWS and sensor failures.
(n) Indication that the TAWS is operating in Basic GPWS mode only.
(o) A means to initiate the TAWS self-test function on the ground.
(p) An interface with the flight recording system to record TAWS alerts and inhibition of FLTA or PDA functions.
(q) Indication to the flight crew where geographical regions of operation or other factors which adversely affect system performance to the extent that the TAWS may be potentially misleading and should not be relied up. If this indication is not practicable, a flight crew procedure may be used to determine whether the navigation system accuracy is acceptable for continued use of the TAWS.
(r) A means for the flight crew to inhibit the FLTA and PDA functions together with appropriate annunciation of the inhibited condition.
(s) A display with a means for the flight crew to select or deselect the terrain information. An automatic pop-up mode may be used with a simple means to deselect the terrain information after an automatic pop-up.
[Issue: CS-ACNS/4]
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