Flashing Yellow A/T Disconnect Light

[r_stopnicki 92]

I have done a search but have not found a thread with a response, so here is my issue. I have lately found that on descent/approaches the A/T disconnect light starts to flash yellow. At the same time, the speed tape starts to fluctuate significantly while the aircraft accelerates beyond the selected airspeed (that it was maintaining quite nicely in the descent prior). At times, I have also noticed a yellow line, above the indicated air speed on the speed tape. It has happened while flying on-line and off line, and I believe that it has happened when flying into unsettled (stormy) conditions. I am sure that the FMC is trying to tell me something (unable to keep speed due to turbulence?) with the flashing yellow A/T disconnect light, but I am not sure what it is and how to react to the situation. (By the way, I thought that icing might be a problem, but the probes heats are on) Can anybody shed a light?Thx!Roberto

[emvaos 13]

Yellow is not disconnect but a warning... What probably happens is you are off the speed target by a margin and IAS moves the wrong way (ie. accelerating while over speed or decelerating while underspeed).

[WebMaximus 345]

I noticed the same problem on my last flight. Have never seen this before and I'm curious if this is a feature or a bug because the flashing is very erratic sort of speak.If some of our real NGX drivers read this maybe they can confirm if this indeed is a signal something is wrong and on par with how the real a/c behaves or if it's an issue with the NGX.

[r_stopnicki 92]

Hi EMVAOS, yes, I understand it is a warning, although I have had difficulty finding reference to it in the manuals and I am not quite sure what it means, becasue it appears suddenly and how to react to it. And Richard, that is exactly (erratic - that is the word I was looking for! :-) ) the way that the speed tape then behaves, erratically moving quickly up and down. I think that this is the way FSX simulates turbulence, but we will wait for a few more folks to chime in. Thank you both.Roberto

[RYR738 8]

Hi EMVAOS, yes, I understand it is a warning, although I have had difficulty finding reference to it in the manuals and I am not quite sure what it means, becasue it appears suddenly and how to react to it. And Richard, that is exactly (erratic - that is the word I was looking for! :-) ) the way that the speed tape then behaves, erratically moving quickly up and down. I think that this is the way FSX simulates turbulence, but we will wait for a few more folks to chime in. Thank you both.Roberto

See FCOM Vol 2 page 206 !! " airspeed differs from commanded value by +10 or -5 knots and is not approaching commanded value. " It is a Boeing Option for any airline. Fred.

[r_stopnicki 92]

Thank you Fred!Your "search" engine is obviously much bigger than mine, and you having flown the NGX might have helped "some" .. Now I understand what is happening. Particularly the "Flaps Not Up" condition. I believe that as a result of the "turbulent weather" the IAS fluctuates significantly and that has triggered the warning. And now the embarrasing question (not out of laziness, but I simply don't know where to look) ... how do you respond to this warning? Out of concern (and frustration) at the quickly approaching runway, I usually just disconnect the A/T and try to keep things going manually, because the A/T does not seem to be able to cope with the quirky IAS indications. Not the easiest at times, as was the case yesterday on a non-precision NDB approach to SLCO (in Bolivia) with 2000 m visibility and 400 ft cielings (it was likely quite illegal to even attempt it). Many thanks again!Roberto

[victorlima01 2]

Definetely busting those NDB minimums Roberto! As long as you keep it in the virtual world not a problem hehe. You'll probably find the answer to what you're looking for in the QRH. I'll take a look for you. But remember that whenever automation gets in ypur way and starts to become a distraction rather than a helpful hand, specially on critical floght phases such as approach, first thing you have to do is fly the airplane, with or without help (in this case, without). So a wild guess here before looking at the documentation but I think the safest thing to do would be to handfly the plane, just like you did. Hopefully Mr. STeiner will agree and shed some more light into the issue.

[paulyg123 124]

I too have the A/T turning off during level flight - no turbulance. I thought I was doing something wrong. I can sometin\mes reactivate it,other times it wont take until I change the throtle position.

[WebMaximus 345]

See FCOM Vol 2 page 206 !! " airspeed differs from commanded value by +10 or -5 knots and is not approaching commanded value. " It is a Boeing Option for any airline. Fred.

Thanks for pointing us in the right direction Fred, amazing how you keep learning new stuff all the time in this a/c :(

[ARM505 0]

..and yes, it comes on quite often IRL, but normally only briefly. The normal response (note that I didn't say 'correct response') is to reach over and push the button to make it go away. :) But if you've had to do that you've obviously checked out exactly what is happening with your speed/thrust setting. I normally see it on the descent with thrust levers at idle, where a combination of energy/flightpath means the aircraft doesn't end up slowing down despite the automatics thinking that it actually should.

[WebMaximus 345]

Thanks for your input Simon, always very exiting to hear how things work in the real a/c!

[r_stopnicki 92]

Great comments Simon. With responses we are getting, now we will know what to look at as lights start flashing (I sure could use a PNF sitting next to me, this thing is way too realistic!).Thanks!Roberto

[FreaK 1]

I have this little "issue" too but only when I'm using REX weather engine.. I almost crash during my approach because of a 25kt headwind... So I decided to try again but this time with the weather generated by FSX (25kt headwind too) and I didn't have any problem. I land properly with no yellow A/T flashing... Weird thing !

[flyfed 3]

Hi EMVAOS, yes, I understand it is a warning, although I have had difficulty finding reference to it in the manuals and I am not quite sure what it means, becasue it appears suddenly and how to react to it. And Richard, that is exactly (erratic - that is the word I was looking for! :-) ) the way that the speed tape then behaves, erratically moving quickly up and down. I think that this is the way FSX simulates turbulence, but we will wait for a few more folks to chime in. Thank you both.Roberto

Have you tried turning off the FS "turbulence" setting? "Off" is recommended at the bottom of page 0.00.15 of the Introduction document.

[WebMaximus 345]

I've seen that recommendation but I decided to keep the turbulence enabled since to me disabling it would have a negative impact on the realism never facing turbulence. I also have FSUIPC registered version which hopefully should keep me away from the most unrealistic wind changes notorious for FSX.