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CajunRon

In approach speed intervention - still can't slow down

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On final approach onto RW35L at DFW.  I am trying to do a "by the book" landing based on the information in Tutorial 1.   After VNAV slows me down to 210 (flaps 1 extended) I pressed the speed knob to get into speed intervention mode.  I have SPD, LOC and G/S activated (in green) on the PFD.     I lower the gear and  I dial in 172 knots and extend flaps 5.   The plane begins to slow but before reaching 172 the speed jumps irratically and won't slow any more.   I extend speed breaks, dial in 154 and begin extending flaps to produce as much drag as I can.  I extend all the way to flaps 30.,  The plane is accelerating, the autothrottle is calling for more power with N1 climbing past 57  I checked to see if I accidentally hit the TO/GA button.  The PFD is still displaying G/S mode, not TO/GA.   I'm sure this is pilot error but I can't figure out what I'm doing wrong.

 

I'm using REX Essential Plus for my weather and the weather at DFW is thundershowers with winds at 350 deg at 9 kts  (yes I know, I'm landing with the wind but my FMC was already programmed for 35L and I wouldn't think 9 kts tailwind would be a big problem...certainly not one that would cause autothrottle to throttle up while I'm calling for a slower speed thru speed intervention)

 

Any ideas what I'm doing wrong?  I checked the "bug file" and didn't see anything indicating any bug in this area.

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Almost sounds like the sim cant decide if it should use the MCP speed (and thus reduce thrust) or increase thrust because of conflicting inputs.

 

So make sure that if you are using thrust levers (joystick), that you have set the option "Thrust lever override AT - Never" in the CDU.

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You can have 15deg of flap out before you get to 175k. You will need to check the manual but I think you can have 5deg out at around 200k and 15deg around 185kt

 

of course I could be completely wrong but its worth a look, it will slow you down big time

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So make sure that if you are using thrust levers (joystick), that you have set the option "Thrust lever override AT - Never" in the CDU.

 

Thanks. I will give that a try.   I actually followed the instructions in the tutorial that says that once the PFD shows the throttle to be in IDLE mode, to move my physical throttle to idle also...which I did.  (I thought it said that this was "real life" ...i.e. moving the physical throttle to idle when the flight computer put the autothrottle to idle)

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PMDG airplanes don't handle turbulence well. You are probably experiencing that along with simulated wake vortexes and anything else REX uses.

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Setting thrust lever override to NEVER did not help.   I'm actually loading a saved "mid-air" flight where it is transitioning from the STAR to the approach.   So the FMC is not starting from the very beginning (takeoff, climb etc).  It's starting from where it was when I saved the flight.  I didn't use the SAVE STATE in the CDU but only FSX's SAVE.  I now suspect this to be the source of the problem. I'll experiment some more. 

 

I'll post any findings.  Thanks.

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Setting thrust lever override to NEVER did not help.   I'm actually loading a saved "mid-air" flight where it is transitioning from the STAR to the approach.   So the FMC is not starting from the very beginning (takeoff, climb etc).  It's starting from where it was when I saved the flight.  I didn't use the SAVE STATE in the CDU but only FSX's SAVE.  I now suspect this to be the source of the problem. I'll experiment some more. 

 

I'll post any findings.  Thanks.

It's very likely the reason of this strange behavior.

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It's starting from where it was when I saved the flight. I didn't use the SAVE STATE in the CDU but only FSX's SAVE. I now suspect this to be the source of the problem.

 

Hi, CajunRon,

 

I doubt the problem is with your reloading of an FSX saved state.  Saving using FSX does save the panel state as it is at the time of the save.  If you are seeing the same settings as when you saved (for example flaps, MCP modes) and the same FMC info (same legs showing, same leg is the next leg, etc.) then your reloaded flight is most likely just fine.

 

i

 


PMDG airplanes don't handle turbulence well. You are probably experiencing that along with simulated wake vortexes and anything else REX uses.

 

CajonRon, from what you are saying, I suspect the weather is the issue.  I don't have any weather addon, but with thunderstorms the wind is gusty.  The autothrottle will try to compensate for rapid windspeed changes.  It is designed to add speed in such situations even if you set the landing speed recommended by the FMC.  Try the same wind,  but without the thunderstorm or other turbulence-producing settings and see if it works better.

 

BTW from what you are saying, you don't have a tailwind, you have a headwind.  At any rate, just keep the wind but lose the turbulence!

 

Mike

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He does have a head wind not a tail wind. 350/9 is the wind coming from a heading of 350@ 9 knots, RWY 35 is perfect.

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pictures. otherwise we cannot really tell what is going on...

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