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Background: I'm a huge aviation enthusiast with a lapsed PPL. Have flown some larger aircraft on MSFS, but never flown anything in real life bigger than a C172.

I was lucky enough to do a bit of Simulator time on a B737 simulator this weekend. One thing I wanted to try out was an ILS approach in very limited visibility. The instructor set me up, and asked what ILS display I was "used to seeing". I described it, and she set it to this - totally what I was expecting:

enter image description here
(Thats the purple vertical bar for centre line and purple blip for glide slope).

So, my question is, what was the "Other" option? This may be specific for a B737, or it may not. Why are there 2 types of instrumentation for an ILS approach? Is one a newer system, and is it therefore preferred.

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up vote 5 down vote accepted

In the Boeing next-generation "NG" flight decks, the PFD can be configured one of two ways. The first way, is the default presentation, where you only see to top of the HSI. The pilot will fly the aircraft via the pips along the bottom and right of the attitude indication (and usually with the flight director cross as well):

enter image description here

If my memory is correct, Boeing, NASA, and others did a number of human factors studies over the years and found that this layout allowed pilots to more quickly understand critical flight information, and this layout is now standard even in GA glass cockpits (e.g. Garmin G1000, Collins Proline).

The second configuration provides a virtual "six-pack":

enter image description here

This configuration is primarily used for airlines that are transitioning between "Classic" and "NG" flight decks. One airline I remember in particular is Southwest, as they had a combination of 737-300/400 and -700/800 aircraft and having a classic configuration on their new flight decks allowed all of their pilots to fly any of the aircraft, without needing significant differences training. The particular presentation can be customized per the airline's needs. An airline will typically move exclusively to the modern PFD display once all of the older aircraft are moved out of the fleet.

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That would be the double needle display. Here are the 3 most common displays:

enter image description here

The one on the left is the one you are used to.

the one in the middle is the classic double needle design where each line pivots on the point at the top or on the left. The one on the right is equivalent to the one in the middle except that the bars don't rotate but just move up and down and left and right.

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Thanks ratchetfreek, as per question is one system newer? Are any the preferred system or just pilot preference? – Jamiec Jun 16 '14 at 12:47
I wouldn't expect B737 to ever show the right two options. Either HSI or the indicators around PFD (they do work similar to the right one, true). – Jan Hudec Jun 16 '14 at 13:01
... or flight director, of course. – Jan Hudec Jun 16 '14 at 13:07

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