Talk:Double switching

Regarding "A Peruvian airplane ... crashed into the sea."
There was a BBC programme (Horizon?) on this many years ago, but I can't find any reference to it now. --Occultations 20:42, 31 July 2007 (UTC)

Is this the flight?
A trawl though hundreds of references for "Attitude Indicator Accident" finds the following as the first match.

The accident in question sounds a bitlike Copa Airlines Flight 201.

Tabletop (talk) 11:02, 30 April 2008 (UTC)

I think you've identified the incident, but I wonder whether it is relevant to an article on double switching. Is there any indication that Copa 201 had a malfunction due to a single switch path? My understanding from the Nova episode was that the pilots had manually selected to display a single artificial horizon on both displays. When that device malfunctioned (due to a fault in the wiring harness), neither pilot has a display selected that would indicate the descrepancy with the other (properly functioning) horizons. Including this incident in this article insinuates that an alternate design (one using double switching) would have prevented this problem. If that is intended, it would be better style to state it more explicitly and provide a citation that supports that conclusion. If that isn't the intent, this bit should be moved to a different article, perhaps a "list of accidents caused by wiring faults". I don't see the relevance of the Seconds from Disaster reference, since the article doesn't list this incident in any of the episodes. Wcoole (talk) 21:24, 19 December 2012 (UTC)


 * Double switching is a form of redundancy.   Tabletop (talk)

Faulty attitude indicator
See Copa Airlines Flight 201

The attitude indicator is duplicated, indeed, triplicated, so that a single fault need not cause a false green and a crash.

Double switching is similar, is that it prevents (most) single faults causing a false green and a crash.

So there is a similarity. Tabletop (talk) 10:19, 2 May 2013 (UTC)

Korean Airline crash
See: Korean Air Cargo Flight 8509

In another crash, the pilot's indicator was apparently faulty, though the other two were working OK. However Korean culture didn't not allow a mere first officer to draw such problems to the attention of the Captain, and the plane slammed into the ground.

Broadly speaking, double switching is a special case of redundancy. Tabletop (talk) 10:31, 2 May 2013 (UTC)

Telephones requiring 4 wires
Where did the requirement for telephones needing 4 wires come from? Telephones require 2 wires. Even in every UK installation, Only 2 (two) wires come into the premises. A third wire is introduced locally but only to support the ringing circuit of older telephones. All modern telephones only use two wires to connect and many only have 2 contacts in the connector plug. DieSwartzPunkt (talk) 11:21, 25 March 2014 (UTC)
 * Telephone circuits only require 2 wires. I am in fact deleting this section for 3 reasons.  1. It is entirely unreferenced.  2.  It is factually wrong.  3. It is not related to the subject of the article as it is addressing earth crosstalk an not double switching.


 * I am also deleting a couple of other sections as they too are addressing earth crosstalk and not double switching. 85.255.235.41 (talk) 14:22, 25 March 2014 (UTC)


 * While multi-channel long distance telephone circuits with intermediate amplifiers can operate with 2 wires, cross talk between the opposing directions can be a problem. This crosstalk is reduced if 4 wires are provided, with amplifiers in one direction are separated from amplifiers in the other direction.   Has DieSwartzPunkt considered the case of long distance multichannel circuits?    Tabletop (talk) 07:07, 26 March 2014 (UTC)


 * DieSwartzPunkt did not consider long distance multichannel circuits because the (now deleted) article section never mentioned them. The subject of the section was telephones and erroneously claimed that telephones use four wires (for all I know they may in some odd systems in some parts of the world, but they certainly don't have to, and certainly don't around here).  DieSwartzPunkt (talk) 12:44, 26 March 2014 (UTC)