No flare with auto land

[downscc 1,327]

1 hour ago, rennman said:

This just in from a real word Delta 777 pilot..

"In other words, if a 777 autolanded at max landing weight at 500fpm, it would likely be considered a hard landing and require an inspection."

You'll forgive me if I favor his report...

https://www.airlinepilotforums.com/delta/112437-777-touchdown-vs.html#post2557886

Are you claiming the PMDG 777 autoland touches down at 500 fpm? 

[scandinavian13 5,192]

20 hours ago, rennman said:

im looking for -250 fpm or less for a "kiss" touchdown...

No.

This will come across gruff, but it's because the Generic VA Experience that most find has some sort of contrived, awful, gamey, worthless "landing rate" competition where -0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001 is ideal.

THIS.
IS.
COMPLETE.
GARBAGE.

STOP.
IT.

AND PROMPTLY tell your VA to (kindly) STOP IT, and perhaps burn the landing rate tables with a DROP TABLE statement...please.

----------

The autoland function wasn't built to satisfy garbage VA stats.

Autoland was built to put the plane on the ground without breaking it, and do so SAFELY. Safe landings are positive, and firm.

...not gamey VA-based garbage [number as shown above] "kiss landings." You want to show off a gamey landing rate? Go for it. Do it manually, and waste runway while doing so. You want the plane to manage the landing? Then enjoy the show, as built, as designed: a firm touchdown.

[Ephedrin 418]

500fpm is about 5 knots... this might be not the best touchdown for a fully loaded 777... but our concern was about hunting a minimum vertical speed for the touchdown and that is one of the greatest mistakes one can do in aviation... the VSI is completely irrelevant on short final. at least as soon as your GPWS starts to call out from 50 to 10 your eyes are at the far horizon and you rise your nose to a firm and definite touch down. if you looked on your VSI you would probably bounce and end up elsewhere but not on the runway. When you aim for the numbers or for the 500 feet markers if you will and do as described you will likely have a proper landing on the 1000 ft marker at the latest.. 

 

while 5 knots against a wall is quite hard, a good landing is normally between 100 and 300 fpm. although it doesn't matter at all. When you're savely down and it felt okay then it WAS okay. There is no reason and no sense for/in trying a 10fpm touchdown. Even if some VAs make a competition around it. They likely haven't understood a landing at all...After 600+ flights for my VA my average landing rate is at 153 fpm and that's where it should be... My ranking is somewhere at 500 but that just shows how wrong many programs use to teach the desktop pilots. all above those that show the landing rate just before you even have deployed your reversers...

[kevinh 409]

I was flying the 777 tonight. I never use autoland but I tried it on this occasion to see what touchdown rate it achieved. FSUIPC recorded it as -172 fpm but subjectively it felt much smoother than that. Indicated rate of climb was almost zero. I've seen so many odd touchdown rates from FSUIPC that I don't regard it as anything more than rough estimate. It doesn't reflect the complex dynamics of touchdown. It's a snapshot of what the vertical speed was when FSUIPC detected aircraft on ground.

[downscc 1,327]

Same as Kevin, I only use autoland for CATIII operations so I loaded a 77W at KIAH and set the GW to 552 klbs and flew a local pattern for a coupled ILS27 approach. I opened a second window with a locked spot view to see exactly when the rear set of tires on the main trucks touched down and grabbed a screenie when it happened so I could study it later.  It appears that on initial contact of the rear tires that the descent rate is about 350 fpm but of course as the second and third set of tires make their touchdown the descent rate smoothly decelerates to nil.  Maybe this is what is giving the OP problems is the misunderstanding of how the six tire main trucks act on landing; rather than a singular event it is spread out between first contact and full contact so it is hard to say that the initial contact is analogous to a 737 touchdown with a single pair of tires on its mains.  The touchdown initial rate of descent on first contact is smoothly decreased to nil over what appears to be an interval of time that exceeds a second, maybe 2 seconds, not sure.  FCOM 14.20.3 eludes to the dampening available during landing, so this is an engineered feature.

Edited March 24, 2018 by downscc

[BrianW 124]

The real 777 Autopilot Flight Director System (AFDS) flare mode is designed to put the aircraft down 450’ beyond the glideslope transmitter at 1.5 feet/second  (90 FPM). The altitude which flare mode is initiated varies based on descent rate to help achieve the values above.

[downscc 1,327]

11 minutes ago, BrianW said:

The real 777 Autopilot Flight Director System (AFDS) flare mode is designed to put the aircraft down 450’ beyond the glideslope transmitter at 1.5 feet/second  (90 FPM). The altitude which flare mode is initiated varies based on descent rate to help achieve the values above.

When is that 1.5 ft/s measured?  If it is when all six tires on the main are down then yes, PMDG has modeled it correctly. In fact, they might not have enough oleo compression since the dampening effect seems to be doing a good job of decelerating that final couple of feet.

[rennman 4]

On 3/24/2018 at 6:09 PM, scandinavian13 said:

Autoland was built to put the plane on the ground without breaking it,

real world pilots say -500 fpm will break it...or at least require an inspection

Edited March 27, 2018 by rennman

[rennman 4]

On 3/24/2018 at 5:28 PM, downscc said:

Are you claiming the PMDG 777 autoland touches down at 500 fpm? 

yes it does for me...i came here to see if that was normal or not...i dont understand people who think it is...

but in any case...i am either doing it wrong or there is a config error

[rennman 4]

On 3/24/2018 at 7:12 PM, kevinh said:

 FSUIPC recorded it as -172 fpm

thank you for confirming...either im making a mistake or the config file is off...which parameter controls flare rate so i can check?

thanks again.

[rennman 4]

On 3/24/2018 at 6:11 PM, Ephedrin said:

 hunting a minimum vertical speed for the touchdown and that is one of the greatest mistakes one can do in aviation...

 

of course...i only check the log after to see...its very hard to tell in flightsim

[kevinh 409]

23 hours ago, rennman said:

thank you for confirming...either im making a mistake or the config file is off...which parameter controls flare rate so i can check?

thanks again.

The 777 has a custom autopilot model by PMDG. There is nothing that you can adjust in aircraft.cfg. 

[30K 72]

The best thing about this landing rate bull*** is that they never take the G-force into account.

It is laughable when they compare their **** and tell me I need to practice because of my bad 221 fpm landing rate.

A -50 fpm landing but with 1.89 G-force feels definitely harder than a -200 1.08 G-force landing but you know I'll just leave this here.

[30K 72]

On 27/03/2018 at 4:22 PM, rennman said:

real world pilots say -500 fpm will break it...or at least require an inspection

Dude when touching down with MLW!

Whenever the situation requires you to land with MLW there will be an inspection because in 99% of these cases something forced you to do that.

The only reason, where not an emergency causes this plan of action, I can imagine is, that you saved a lot of fuel due to favorable winds but these would need to be strong word not allowed winds.

 

Furthermore:

I just conducted an CATIII Autoland at KDEN. The landing rate was -381fpm so much for this "they always touch down with 500".

Edited March 30, 2018 by 30K

[BlueStar 323]

28 minutes ago, 30K said:

Dude when touching down with MLW!

Whenever the situation requires you to land with MLW there will be an inspection because in 99% of these cases something forced you to do that.

The B777 is certified to land at 10 feet per second at MGLW and 6 feet per second at MGTOW. It was not unusual in my world to land at or near MGLW and takeoff at or above MGTOW.