B777 Grnd Prox Light
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Joined: Mar 2007
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From: Up North….
B777 Grnd Prox Light
A simple question...I hope!
On the GPWS G/S INHIBIT switch on the B777, in the case of DONT SINK, SINK RATE, TERRAIN, TOO LOW FLAPS,TOO LOW GEAR,TOO LOW TERRAIN
Does the whole of the switch light up, i.e. GND PROX G/S INHB? Or just the GND or the GND PROX? (Examples in the attached images)
Simple question I know but the FCOM isn't very clear and it seems strange that the whole thing including the G/S INHB would light up for example for a DONT SINK alert
On the GPWS G/S INHIBIT switch on the B777, in the case of DONT SINK, SINK RATE, TERRAIN, TOO LOW FLAPS,TOO LOW GEAR,TOO LOW TERRAIN
Does the whole of the switch light up, i.e. GND PROX G/S INHB? Or just the GND or the GND PROX? (Examples in the attached images)
Simple question I know but the FCOM isn't very clear and it seems strange that the whole thing including the G/S INHB would light up for example for a DONT SINK alert
Joined: Feb 2004
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From: Australia
Next time you're on the aircraft, try a Master Dim and Test light test and look at the relative sizes of the PROX and G/S INHB lettering. If the 777 is anything like the 747-400, the "G/S INHB" lettering is hardly noticeable due to its size. Pictures in FCOMs may be misleading.
Last edited by NSEU; 17th June 2016 at 13:26. Reason: Addition of picture
Joined: Jun 2000
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From: last time I looked I was still here.
Felix: I think what wiggy is hinting at is that you have 3 questions running on Tech Log. These a simple questions you could and should be asking your in-house instructors. They are simple questions; they should know the answers. They are also items you could ask to see in the simulator. In that way you would have your answers much more quickly and with much more clarity. On Prune, as we have seen over the years, there are quite differing opinions and some down-right wrong answers. Wiggy is suggesting you would be better served in your quest for knowledge by consulting your own training organisation.
Thread Starter
Joined: Mar 2007
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From: Up North….
well for a start the simulator is something that we don't often see as you I am sure are aware. When I have a question and I'm sitting home sometimes the easiest way and quickest way is to ask on here and also to ask the more traditional sources, that tend to take much longer to answer. The whole point of Prune is to ask questions, be they simple or not, you have the choice to answer or not....the number and the nature of my questions really are irrelevant.
Joined: Feb 2004
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From: Australia
I agree with Felix. Using up valuable sim time with dozens of small questions seems wasteful. Yes, posting questions in a public forum does give rise to differences in opinion, but they are usually resolved. If there are any queries unresolved (sometimes due to differences in procedures), then is the time to ask your tech guys.
Questions in public forums also increases awareness and may offer perspectives not found elsewhere.
Personally, I look forward to adding my tuppence-worth (helpful or otherwise)
Questions in public forums also increases awareness and may offer perspectives not found elsewhere.
Personally, I look forward to adding my tuppence-worth (helpful or otherwise)
Joined: Apr 2008
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From: nowhere
I have to admit, this one is quite minor but I am happy with the questions. Otherwise it will just be Airbus discussion. And that would be unacceptable. 
And to be honest, none of us seem to know. So after your next sim, let us know.
And to be honest, none of us seem to know. So after your next sim, let us know.
Joined: Feb 2004
Posts: 1,410
Likes: 37
From: Australia
You have to wonder why the lettering "G/S INHB" was even included in the switch design.
If the G/S INHB legend doesn't light up during general GND PROX warnings, when would it illuminate? The switch is black when there are no warnings (so the legends are not visible).
Note that Korry switches only have 4 bulbs: Two (side by side) for the upper switch half, two (side by side) for the lower half. There is no individual control for single lamps in a pair, which means that if the G/S INHB illuminates during a light test, it has to illuminate during a ground proximity warning.
I doubt very much that GND only illuminates during ground proximity warnings (that would be nonsensical). Both GND and PROX must illuminate.
The only way the switch manufacturers could stop only the G/S INHB legend illuminating is by putting some kind of obstruction between the lower lamp pair and the G/S INHB legend. If they did that, the "G/S INHB" legend would never be seen (including during lamp tests).
If the switch is pushed below 1000', but prior to a glideslope warning, is there any visual confirmation that the inhibit mode has become active?
If the G/S INHB legend doesn't light up during general GND PROX warnings, when would it illuminate? The switch is black when there are no warnings (so the legends are not visible).
Note that Korry switches only have 4 bulbs: Two (side by side) for the upper switch half, two (side by side) for the lower half. There is no individual control for single lamps in a pair, which means that if the G/S INHB illuminates during a light test, it has to illuminate during a ground proximity warning.
I doubt very much that GND only illuminates during ground proximity warnings (that would be nonsensical). Both GND and PROX must illuminate.
The only way the switch manufacturers could stop only the G/S INHB legend illuminating is by putting some kind of obstruction between the lower lamp pair and the G/S INHB legend. If they did that, the "G/S INHB" legend would never be seen (including during lamp tests).
If the switch is pushed below 1000', but prior to a glideslope warning, is there any visual confirmation that the inhibit mode has become active?
