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discountinvestigator
7th Mar 2006, 21:54
Hi,

Forgive me please for this basic question which appears to be confusing a few 320 pilots.

If you have an ADR 1 failure, then you switch the system so that Captain's displays get information from ADR 3. ADR 1 feeds into EGPWS and GPWS functions.

Some airlines appear to be switching off GPWS TERR, some GPWS SYS and some both at this point.

So, what does ADR 1 feed? Why do I lose the GPWS rad alt fed functions if ADR 1 fails, or does ADR 1 feed in rad alt information to GPWS. Why do I lose the Glideslope function with ADR 1?

Sorry, but I do not have access to the manuals, merely extracts at the moment. I think I will go back to the P1 compass and a DHC1 shortly.
sabenaboy
8th Mar 2006, 08:40
Here"s what my FCOM says:

http://home.scarlet.be/~kd6qe2mr/adr1fault.jpg

And here an extract from FCOM 1.34.10:

http://home.scarlet.be/~kd6qe2mr/adirs_description.jpg

And here's a picture:

http://home.scarlet.be/~kd6qe2mr/gpws_schema.jpg

I'm afraid that that's all I could find in the FCOM.
discountinvestigator
8th Mar 2006, 10:17
Hi, the simulator pops up in the ECAM drills with the requirement to switch the GPWS to OFF. Should it say the GPWS TERR instead? Is this an ECAM error, a simulator error or my brain?

If you switch GPWS to off, then the working RA 1 radio altitude input is eliminated, the ILS box glide function goes as well.

The TERR switch takes out TAD and TCF (sorry, but I do not know what these are) only and leaves Modes 1 to 5 available.

Thank you for the diagram to assist in the debate!
sabenaboy
8th Mar 2006, 13:25
The TERR switch takes out TAD and TCF (sorry, but I do not know what these are)
I don't know either. I hope someone will be able to tell us.
safetypee
8th Mar 2006, 13:27
The TERR switch takes out TAD and TCF (sorry, but I do not know what these are) only and leaves Modes 1 to 5 available.
TAD is the Terrain Awareness Display (EGPWS terrain map) and TCF is Terrain Clearance Floor (EGPWS computation / warning boundary). If these are off i.e Terr Off/Fault then the Enhanced functions of GPWS will not be available, but the old style / standard GPWS (modes 1-5) should work. Remember that the old GPWS does not give you the same standard of protection as EGPWS does – take care.
See: www/egpws.com - ‘Operation’ – ‘Pilots Guides’ for more info