Landing Issues

[nyydave 0]

Hey everyone,

 

I'm having a strange problem in about 75% of my landings where the 777 hits the runway and immediately goes full throttle. I feel like I have to have the aircraft set up correctly, speed at VREF+5 with A/T, autoland configured, speed breaks armed, auto breaks at 3. My physical throttle stays idle since before TOD. After a second on the ground I right click disarm A/P and give it a second right click to silence the alarm. By this point the 777 is usually throttle up and I fight it and click frantically to shut off any auto controls but it's like they're overriding me?

 

Let me know what I did silly...

 

David Chapman

[Mike777 163]

 

 

By this point the 777 is usually throttle up and I fight it and click frantically to shut off any auto controls but it's like they're overriding me?

 

Hi, David,

 

Looks like your approach setup is fine.  Your external throttle might be sending a spike.  Try disconnecting it and see if the problem goes away.  Also, try setting the throttle to "never" override the autothrottle and see if the problem goes away., although personally I don't like this setting as it is unrealistic.

 

Another thing to check: what mode is showing on the PFD at landing: Spd, Idle, or something else (autothrottle should go to idle just before touchdown)?

 

Mike

[77west 139]

I actually had the opposite for the first time ever, taking off from Auckland I advanced the thrust levers (Saitek) to 55%, hit toga switch and manually pushed them to the stops, as I always do, but about 10 seconds later the engines firewalled to like 108% N1 for some reason. I just manually retarded to the correct N1 and continued the roll. I think I might have to recalibrate my hardware throttles.

[scandinavian13 5,192]

 

 

hit toga switch and manually pushed them to the stops, as I always do, but about 10 seconds later the engines firewalled to like 108% N1 for some reason.

 

...because that's not what you're supposed to do. :wink:

 

In the real plane, the servos in the throttles keep the throttle levers in sync with the commanded thrust.  At a point in the takeoff roll, the A/T mode drops to HOLD.  This allows the crew to close the throttles easily in the event of an RTO.  As such, the A/T just releases the servo control and looks to see if the crew changes the throttle position in the real plane.  In your sim, however, since the A/T looks to see if your throttle position has "changed" since it was last set, it reverts to your physical throttle's position.

 

So, if you hit TOGA and your N1 increased to 100% (not the firewall), if your hardware throttle doesn't match that position, when it drops to HOLD, the sim will reset the throttle to your physical throttle location.  If you put it on the forward stops, as soon as it drops to HOLD, your sim throttle will be on the forward stops.

 

This is briefly explained in the Intro Manual, along with options on how to avoid issues like this (for you, it might be good to use the "always override your hardware" option if you don't want to bother with it).  I personally used "in hold mode," which is the default, along with the option to see your hardware position "when moving" to help sync the throttles on the takeoff roll.

 

You can see me using the hardware position option here (and I mention it in the video when it appears - look at the N1 gauge for a blue arc around 25:45):

 

[nyydave 0]

 

 

Another thing to check: what mode is showing on the PFD at landing: Spd, Idle, or something else (autothrottle should go to idle just before touchdown)?

 

That is a good question, and I'll have to check it out as I can't recall. I'll try the setting to disregard my throttle too just in case thanks.

[Mike777 163]

 

 

In your sim, however, since the A/T looks to see if your throttle position has "changed" since it was last set, it reverts to your physical throttle's position.

So, if you hit TOGA and your N1 increased to 100% (not the firewall), if your hardware throttle doesn't match that position, when it drops to HOLD, the sim will reset the throttle to your physical throttle location. If you put it on the forward stops, as soon as it drops to HOLD, your sim throttle will be on the forward stops.

 

On my system, the key thing is not to touch my manual throttle once I've pressed TOGA on takeoff roll.  As long as I am careful not to touch my manual throttle during takeoff (especially once the A/T goes into HOLD), I don't have a problem.  I think that sometimes I just leave my manual throttle alone after spooling up to @ 55% N1, other times I do firewall it, but before the A/T goes into HOLD.  Maybe some other manual throttles keep transmitting their positions manually, causing the problem on takeoff you and Dave are describing.  I use a Microsoft Sidewinder or a Logitech Extreme 3D Pro.  I have my manual throttle set to ALWAYS override autothrottle, the most realistic setting.

 

Mike

[scandinavian13 5,192]

 

 

Maybe some other manual throttles keep transmitting their positions manually, causing the problem on takeoff you and Dave are describing.

 

I think it's more of a control spike issue in most cases.  Either way, it's not quite a problem, per se.  It's a limitation between the sim and the real aircraft since most people don't have servo-equipped throttles.

 

 

 

I have my manual throttle set to ALWAYS override autothrottle, the most realistic setting.

 

Depends on your definition of "realistic."

 

If it's the fact that on the real plane, taking manual control of the throttles will override the commanded A/T setting, then sure.

 

At the same time, since most people don't have realistic servo throttles, HOLD ONLY could also be considered pretty realistic because that's the only time A/T hands direct control over to you (and makes it easier to do so - in modes other than HOLD, you're going to be fighting servo pressure from my understanding).

 

Most realistic, to me, would be NEVER override with servo throttles; or HOLD only for manual-only.  Just me, though...

[Mike777 163]

At the same time, since most people don't have realistic servo throttles, HOLD ONLY could also be considered pretty realistic because that's the only time A/T hands direct control over to you (and makes it easier to do so - in modes other than HOLD, you're going to be fighting servo pressure from my understanding).

 

Kyle,

 

You are quite right about that.  As I understand it, in the real T7 the pilot can maintain the throttle where he wants it by keeping his hand on the throttle levers.  On most FS systems, certainly on mine, I would have to keep making small movements on the throttle lever just to keep it where I want it.

 

BTW, my understanding of what happened to Asiana 214 is that the PF had FLC set, along with the missed approach altitude, so the aircraft started to power up and climb.  He then forced the levers to minimum and held them there, causing the A/T to go into HOLD, no more airspeed regulation, and we all know the rest.

 

Mike

 

 

That is a good question, and I'll have to check it out as I can't recall. I'll try the setting to disregard my throttle too just in case thanks.

 

David,

 

From what you said about your throttle levers causing the engines to firewall on takeoff, and what Kyle said about spikes, I am guessing you are getting a spike on landing.  If you set the manual throttle either to NEVER override autothrottle or override only in HOLD, this problem should go away.  The A/T should never go into HOLD during final approach.  It should be either in SPD or, shortly before touchdown, IDLE.  This should be the case on an Autoland, on an ILS approach where you switch of the Autopilot (but not the Autothrottle) at some point, and on a VNAV approach.

 

Although PMDG does not advise it, I use FSUIPC for my throttle control.  It has a box to eliminate spikes that you can check.  If FSUIPC throttle causes you problems, you can always go back to FSX.

 

Mike

[nyydave 0]

Alright, I set the joystick to "Never" override the throttle and everything is fine now.

 

To answer an earlier question, my PFD speed goes from "SPD" on approach to "Idle" on touchdown. It must have been a joystick issue, thanks everyone.

[77west 139]

...because that's not what you're supposed to do. :wink:

 

In the real plane, the servos in the throttles keep the throttle levers in sync with the commanded thrust.  At a point in the takeoff roll, the A/T mode drops to HOLD.  This allows the crew to close the throttles easily in the event of an RTO.  As such, the A/T just releases the servo control and looks to see if the crew changes the throttle position in the real plane.  In your sim, however, since the A/T looks to see if your throttle position has "changed" since it was last set, it reverts to your physical throttle's position.

 

So, if you hit TOGA and your N1 increased to 100% (not the firewall), if your hardware throttle doesn't match that position, when it drops to HOLD, the sim will reset the throttle to your physical throttle location.  If you put it on the forward stops, as soon as it drops to HOLD, your sim throttle will be on the forward stops.

 

This is briefly explained in the Intro Manual, along with options on how to avoid issues like this (for you, it might be good to use the "always override your hardware" option if you don't want to bother with it).  I personally used "in hold mode," which is the default, along with the option to see your hardware position "when moving" to help sync the throttles on the takeoff roll.

 

You can see me using the hardware position option here (and I mention it in the video when it appears - look at the N1 gauge for a blue arc around 25:45):

 

http://www.youtube.com/watch?v=6h_IAoL6Pik

Thanks Kyle, I do realize I am not doing it entirely the correct way, perhaps I should have said, as per PMDG Tutorial page 63, after THR REF is announced, I push the thrust levers fully forward. If I don't do this, I get thrust rollback when mode changes to HOLD. In my post I was only surprised because after many, many 777 flights, it was the first time that when entering HOLD mode, the thrust actually increased. (opposite to the rollback if levers left at 55%, I only ever had rollback, NOT increase to max thrust) I presume this is something to do with my hardware throttles. I have not had this issue before, I do use "override in hold mode" and also option to see physical lever position. I might have to change it though to "always override", I think whilst troubleshooting some other CTD issues I may have lost calibration.

 

It was kinda fun though seeing a pretty light 777 jump from 90% to 108%, almost as if I lit the afterburners!

 

Unlike some people on here I have actually read all of the manuals, AND watched your tutorials

 

Thanks for that info.

 

Regards

[scandinavian13 5,192]

 

 

Unlike some people on here I have actually read all of the manuals, AND watched your tutorials

 

Thanks for the support!  :wink:

(and for doing your homework!)