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skyrider

"SINGLE CH" During Dual Channel Approach

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Just an observation: When selecting the second autopilot during a dual channel approach "CMD" remains annunciated until glideslope capture, at which point it changes to "SINGLE CH" followed by "CMD" following a successful self test. What should happen is that "CMD" should change to "SINGLE CH" the moment the second autopilot is selected & not be delayed until glideslope capture. The subsequent change is correct. Cheers, Doug


Doug Boynton

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Hmmm. I thought it went from CMD to SINGLE CH on LOC cap and then to CMD when the self-check was completed, the 2nd A/P connected and FLARE was armed. You'll be SINGLE CH if you've got one A/P selected once LOC has captured.


Matt Cee

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Hmmm. I thought it went from CMD to SINGLE CH on LOC cap and then to CMD when the self-check was completed, the 2nd A/P connected and FLARE was armed. You'll be SINGLE CH if you've got one A/P selected once LOC has captured.
Matt, you are quite correct, my apologies for the disinformation! At least we are agreed that SINGLE CH occurs before glideslope capture. Cheers, Doug

Doug Boynton

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Hmmm. I thought it went from CMD to SINGLE CH on LOC cap and then to CMD when the self-check was completed, the 2nd A/P connected and FLARE was armed. You'll be SINGLE CH if you've got one A/P selected once LOC has captured.
Another issue for SP1 or a hotfix please... Doug

Doug Boynton

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Out of interest, do you guys file tickets for these sorts of things or just hope someone important stops by and sees it? sig.gif

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Out of interest, do you guys file tickets for these sorts of things or just hope someone important stops by and sees it? sig.gif
I just hope that someone important stops by, sees it & acts on it! What's the best method for getting it to the right guys? Doug

Doug Boynton

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People are still having a problem understanding this !!! If you capture the localizer with VOR/LOC it will announce CMD.( you cannot have single channel in VOR/LOC mode !!!)If you capture the localizer with APP it will announce Single Channel.it will be Single Channel untill 1500 feet and then change to Land 3 for the Collind MCP or back to CMD for the Honeywell MCP.( provided you have also captured the glideslope of course.) This is correct and has been correct since Hotfix 3.Before hotfix 3 it was not correct. Fred.


Frederic Steiner.

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People are still having a problem understanding this !!! If you capture the localizer with VOR/LOC it will announce CMD.( you cannot have single channel in VOR/LOC mode !!!)If you capture the localizer with APP it will announce Single Channel.it will be Single Channel untill 1500 feet and then change to Land 3 for the Collind MCP or back to CMD for the Honeywell MCP.( provided you have also captured the glideslope of course.) This is correct and has been correct since Hotfix 3.Before hotfix 3 it was not correct. Fred.
Well, if you want to be picky, the self-check starts at 1500'. That takes ~200' feet and then you'll get CMD or LAND.

Matt Cee

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People are still having a problem understanding this !!! If you capture the localizer with VOR/LOC it will announce CMD.( you cannot have single channel in VOR/LOC mode !!!)If you capture the localizer with APP it will announce Single Channel.it will be Single Channel untill 1500 feet and then change to Land 3 for the Collind MCP or back to CMD for the Honeywell MCP.( provided you have also captured the glideslope of course.) This is correct and has been correct since Hotfix 3.Before hotfix 3 it was not correct. Fred.
Please see FCOMv2 page 4.20.4 I though it was usual to capture the localiser first using VOR/LOC & only then select APP in order to avoid false glideslopes. What is the correct sequence of annunciations in this case? The fact is that, at the moment the NGX does not annunciate SINGLE CH until glideslope capture which is incorrect, it should do so sometime before... Cheers, Doug

Doug Boynton

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Well, if you want to be picky, the self-check starts at 1500'. That takes ~200' feet and then you'll get CMD or LAND.
To be even pickier ! LOL.gif The self check will only start at 1500 ft if you have selected both autopilots !If for example you only selected the 2nd autopilot at 1200 ft the self check would start at 1200 ft. Fred.
Please see FCOMv2 page 4.20.4 I though it was usual to capture the localiser first using VOR/LOC & only then select APP in order to avoid false glideslopes. What is the correct sequence of annunciations in this case? The fact is that, at the moment the NGX does not annunciate SINGLE CH until glideslope capture which is incorrect, it should do so sometime before... Cheers, Doug
Most airlines will be using APP for localizer and glideslope capture.If you do press VOR/LOC first the annunciation will be CMD.It will change to Single Channel after pressing APP and capturing the glideslope. Fred.

Frederic Steiner.

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It will change to Single Channel after pressing APP and capturing the glideslope. Fred.
That's what the NGX does, but: According to the FCOM it annunciates SINGLE CH on localiser capture, not glideslope capture. Assuming you have a single AP engaged in command mode it will be annunciating CMD anyway, even before localiser capture. Doug

Doug Boynton

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That's what the NGX does, but: According to the FCOM it annunciates SINGLE CH on localiser capture, not glideslope capture.
Yes that is correct !! We are talking about capturing the localizer in APP mode.APP mode will always announce single channel for localizer capture. VOR/LOC mode will not. ( The NGX does this perfectly) Fred.

Frederic Steiner.

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To be even pickier ! LOL.gif The self check will only start at 1500 ft if you have selected both autopilots !
... plus three seconds... sig.gif

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Yes that is correct !! We are talking about capturing the localizer in APP mode.APP mode will always announce single channel for localizer capture. VOR/LOC mode will not. Fred.
I agree with you regarding capturing the localiser in APP mode (FCOMv2 4.10.15) Do you have any reference to show what happens using VOR/LOC mode? Doug

Doug Boynton

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so when is the appropriate time to engage the other AP, or in most cases CMD B? A lot of the time, for me anyway, I have a hard time getting both A and B to stay connected at the same time. Thanks!


Ty J. Peres - KBZN

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