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 10 Autopilot master caution and yellow line (Read 1523 times)
tommchowat
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Autopilot master caution and yellow line
Oct 12th, 2020 at 4:20pm
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Okay, last one didn't work, I'll try this one;

Autopilot master caution and yellow line through GS FMA during manually flown ILS approach occurs every time at about 20ft RA.

Screenshot below.

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Captain Sim
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Re: Autopilot master caution and yellow line
Reply #1 - Oct 14th, 2020 at 10:43am
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From what we see on the screenshot:
- You are way above glideslope
- AP is OFF
So what do you expect from the master caution, GS indication and EICAS message in that condition?

  
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tommchowat
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Re: Autopilot master caution and yellow line
Reply #2 - Oct 14th, 2020 at 11:57am
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AngryCaptain Sim wrote on Oct 14th, 2020 at 10:43am:
From what we see on the screenshot:
- You are way above glideslope
- AP is OFF
So what do you expect from the master caution, GS indication and EICAS message in that condition?



Yeah, the autopilot is off, it was disconnected earlier in the approach. There's no way it should be giving a master caution at 10 feet off the ground. The master caution and line through the GS FMA means the autopilot is operating in a degraded condition. Considering it wasn't even engaged, it means it's not operating at all. So if it's not operating at all, it shouldn't be warning me that it's degraded.

On a side note, you will always end up either full scale above or below the glideslope at 10 feet off the ground when landing manually. There's no pilot who can follow the GS all the way through the flare and touchdown, it just doesn't happen. And my reference for that is an ATPL with 4000 hours on the 737-800 and 1000 hours on the 747-400 (which is the type I'm current on now).

I really don't think you should be trying to pass this off as normal behaviour, unless every 757 pilot in real life gets an autopilot caution during manual flight at 10 feet off the ground. I find that hard to believe, but I'm happy to be proven wrong.
  
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tommchowat
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Re: Autopilot master caution and yellow line
Reply #3 - Oct 14th, 2020 at 12:02pm
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User CaptLE also has this issue on Page 2 of Systems and Dynamics thread in bug tracking.
  
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Alex T
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Re: Autopilot master caution and yellow line
Reply #4 - Oct 14th, 2020 at 2:32pm
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I can’t believe they tried to blame you on above glide slope 🤣 obviously that person doesn’t know if the GS were centered to wheels down, you would’ve broken the plane in to many pieces. Their logic for glide slope deviation is definitely off.
  
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Re: Autopilot master caution and yellow line
Reply #5 - Oct 14th, 2020 at 3:19pm
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tommchowat wrote on Oct 14th, 2020 at 11:57am:
757 pilot in real life

Let's wait for some feedback from that guy.
  
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JEB
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Re: Autopilot master caution and yellow line
Reply #6 - Oct 14th, 2020 at 4:41pm
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Captain Sim wrote on Oct 14th, 2020 at 3:19pm:
tommchowat wrote on Oct 14th, 2020 at 11:57am:
757 pilot in real life

Let's wait for some feedback from that guy.


As requested, 757/767 pilot here with 4000+ hrs.

Can confirm glideslope deviation can not casue an autopilot caution during manual flight.

I have also experienced the issue reported here on many occasions and it is certainly a sim issue - does not happen irl.
  
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CaptLE
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Re: Autopilot master caution and yellow line
Reply #7 - Oct 14th, 2020 at 5:15pm
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tommchowat wrote on Oct 14th, 2020 at 12:02pm:
User CaptLE also has this issue on Page 2 of Systems and Dynamics thread in bug tracking.


Yes, I posted this as a bug in the 1.503 version with the manual references; it was highlighted as 'on the bug list' in early May.

It wasn't in the 757 changelog for 1.6, but in the CS 767 changelog, it's shown as fixed in version 0.95 (13th May '20).

Was that just an error or was it indeed changed back then? (I don't have the 767).
It would be great to see it fixed on this aircraft.

Thanks
  

Liam Evans
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Re: Autopilot master caution and yellow line
Reply #8 - Oct 15th, 2020 at 9:44am
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JEB wrote on Oct 14th, 2020 at 4:41pm:
Can confirm glideslope deviation can not casue an autopilot caution during manual flight.

I have also experienced the issue reported here on many occasions and it is certainly a sim issue - does not happen irl.

Thanks.
So the only issue is, AP disengagement should not trigger the master caution light. Right?
  
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Alex T
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Re: Autopilot master caution and yellow line
Reply #9 - Oct 15th, 2020 at 10:18am
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Should also not get the line through GS when flaring

“ An alert is displayed if a significant deviation from localizer or glideslope occurs: the respective deviation scale changes color from white to amber and the associated pointer flashes. The alert stops when deviation returns to within normal limits. The glideslope alert is inhibited when below 100 feet RA. During a localizer alert, the stem of the rising runway symbol also flashes.”
  
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tommchowat
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Re: Autopilot master caution and yellow line
Reply #10 - Oct 15th, 2020 at 10:42am
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Captain Sim wrote on Oct 15th, 2020 at 9:44am:
JEB wrote on Oct 14th, 2020 at 4:41pm:
Can confirm glideslope deviation can not casue an autopilot caution during manual flight.

I have also experienced the issue reported here on many occasions and it is certainly a sim issue - does not happen irl.

Thanks.
So the only issue is, AP disengagement should not trigger the master caution light. Right?


Not really.

If the autopilot was engaged and it was unable to track the glideslope due to system degradation or bad glideslope signal, then the master caution and line through the GS FMA would be correct. However, in this case, the autopilot is already disengaged. There should be no master caution relating to the autopilot whilst it's disengaged.

Also, as noted above, in manual flight, if you deviate significantly from glideslope, you shouldn't get a yellow line through the FMA, but you should get 'glideslope' GPWS warning, except under 100 feet RA.

How you have it at the moment, the system is acting like the autopilot is engaged, when it's actually not. Hopefully this is clear.
  
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CaptLE
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Re: Autopilot master caution and yellow line
Reply #11 - Oct 15th, 2020 at 12:01pm
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Also the AUTO PILOT light immediately left of the upper EICAS should be inhibited, along with the EICAS message and the master caution light when manually landing after disconnecting the autopilot on the ILS approach.

These are all triggered by the line through G/S which shouldn't be occurring in this configuration and phase of flight.

Manual Part II:
"Autopilot (AUTO PILOT) Light:

Illuminated (amber) -
- a degraded operating condition exists in engaged autopilot" (page 97)

"AUTOPILOT, Caution, AUTO PILOT, Beeper

The engaged autopilot is operating in a degraded mode.
Engaged roll and/or pitch mode may have failed." (page 115)
  

CS757-_AUTOPILOT_EICAS_001.jpg ( 411 KB | 75 Downloads )
CS757-_AUTOPILOT_EICAS_001.jpg

Liam Evans
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JEB
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Re: Autopilot master caution and yellow line
Reply #12 - Oct 15th, 2020 at 12:15pm
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Captain Sim wrote on Oct 15th, 2020 at 9:44am:
JEB wrote on Oct 14th, 2020 at 4:41pm:
Can confirm glideslope deviation can not casue an autopilot caution during manual flight.

I have also experienced the issue reported here on many occasions and it is certainly a sim issue - does not happen irl.

Thanks.
So the only issue is, AP disengagement should not trigger the master caution light. Right?


Essentially all autopilot cautions/warnings are inhibited during manual flight. This includes the amber lines through FMAs.
  
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