TDZ & FPM GRADING

[ajurt37]

Travis,

Just to chime in on the soft landing, with airliners on a contaminated runway you usually want the plane firmly on the ground, so too soft a landing would be a no go. Apparently even an Airbus Autoland has some variance with 2ft/sec on the low side, 3ft/sec average and 5ft/sec on the high side).

Andre

[Travis]

At the end of this post is a graph I threw together. The first two columns are Andre's Airbus (low and high) Autoland values translated to FPM - thanks to Andre! - and my observations of the default FSX ILS 'autoland' values made many years ago.

My FSX ILS autoland tests gave me anywhere from 600 to 800 FPM when I allowed it to take the test aircraft to the ground.  Which IRL would only be done under a CAT III(b or c) landing.  CAT I or CAT II landings usually call for the autopilot to be disco'ed a few hundred feet AGL and hand flown to the ground.

Landing speed seemed to matter in terms of the vertical speed noticed.

I used the freeware RAAS 2.0 add-on to give me the landing rates. FSCaptain functioned as a backup... which was very close to the RAAS findings.
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The other four columns are the low-to-high rates to achieve an "FSCaptain PAX Nice Landing" compliment.

I believe our options would allow any Captain to define how their PAX should react under reasonable terms.  I am willing to accept arguments for our three new options, and even arguments to allow other levels.

We do need to keep the existing set in place mostly out of a sense of "this is how you have been accustomed to make a 'nice landing'".
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I'm still interesting in defining a non-overweight Hard Landing / Inspection floor.  (The current Alpha 2 Test floor is set to 1000FPM, but I can easily go as low as 800 - or more if I've been convinced of something.)

The Hard Landing floor could be a simple one-size-fits-all approach, or it could be coupled to aircraft size classes, or even to allow variants for individual aircrafts.

And of course a Hard Landing (Inspection) is completely separate from a "PAX Nice Landing".  The former is dictated by aircraft manufacturers and / or aviation authorities.  The latter comes from "human subjective perception."



Best regards,

[ajurt37]

Travis,

>>I believe our options would allow any Captain to define how their PAX should react under reasonable terms.
Agreed

We do need to keep the existing set in place mostly out of a sense of "this is how you have been accustomed to make a 'nice landing'".
Agreed as well.

As for a hard landing floor, this seems to be somewhat company specific in the real world and not always necessarily follow the aircraft manufacturer recommendations...

I like this quote I found in a forum:
"As my 757 base training instructor once told me "it's better to make a firm landing on the aiming point, than a greaser outside the touchdown zone"...

It never ceases to amaze me how (having used our judgement and skill to safely and efficiently transport them from A to B) passengers overall opinions of a "good or bad" flight are restricted just to those few seconds around touchdown. That's what makes a good flight for them, smooth and soft.

In essence, their argument is totally flawed. They would prefer a smooth and soft touchdown but in heavy rain onto a wet runway if I did a greaser and ended up a couple of thousand feet beyond the aiming point their opinion would soon change as we aquaplane off the end of the runway into the mud!"

Andre

[Travis]

Hi Andre,

I more than agree with your assessment that passenger "concerns" are often contra the "concerns" of the airlines (or of their insurers, etc.).

FSCaptain doesn't track the history of airliner use (although we could), which is one of the reasons behind our Inspection system.  In short, if a Captain feels that they botched something up on a flight leg (or had an aircraft system failure) which would (IRL) prevent the aircraft from being moved - not to mention flown - they could enable the ENFORCE_INSPECTIONS=1 option.

The most that could do is to prevent a multi-leg flight from continuing, ore prevent a new flight from beginning.

If you are running the FCDU.EXE and you are given an inspection, then if you really want to make another flight, just close the FCDU.EXE and restart it.  (Hey Presto, no damage....)

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If I read you correctly that some airlines have... diverted from some aircraft manufacturer's guidance on what constitutes an inspective event - and please let me know if I misread your post - then on my Monday, I could add an airline-specific value for something like MAX_INSPECTIVE_LANDING_VSPEED to the list for Alpha 3.

I hope to release Alpha 2 on my upcoming Tuesday.  I'll post the current Alpha Changelist late on my Monday.

I would appreciate any input on what should be the default "Minimum Inspective Landing VSpeed", as well as a good minimum value for any general circumstances.  (This is the value which would enforce a flight-ending aircraft inspection after all.)

Personally, I really wouldn't want to go below 900fpm because the default FSX ILS autoland seemed to top out at around 800fpm and I don't want us to penalize a CAT III-ish landing.  (But feel free to tell me I'm wrong!)

Do know that I never tested FS9 or P3D4 for their ILS autoland values... so if Captains would like to test those simulators with "default-ish" aircraft, I would be happy to make such an adjustment be simulator-specific.

Just as easily, I want to have aircraft-specific "Minimum Inspective Landing VSpeed values" - which would be overridden by an associated airline specific value, if we do go in that direction.  (If I didn't misread your post....)

Best,

[Travis]

Nov 24, 2019 16:38:43 GMT -5 ajurt37 said:

"In essence, their argument is totally flawed. They would prefer a smooth and soft touchdown but in heavy rain onto a wet runway if I did a greaser and ended up a couple of thousand feet beyond the aiming point their opinion would soon change as we aquaplane off the end of the runway into the mud!

I missed replying to this section....

Even today if a Captain totally greases their landing and does everything else in order to get a PAX Nice Landing bonus... if there's a runway overrun, the bonus is nixed.

Best,

[ajurt37]

Travis,

No, you read that right. That was a quote from a person who had worked for 8 different airlines.

Re the "Minimum Inspective Landing VSpeed" I agree it has to be above the FS9/FSX/P3D Autoland values which are usually around 7-800 feet on average. I haven't done an autoland in a long time. Here in Canada it is (or was?) mandatory to do an autoland once every 6 month but they're usually done in good weather. However I've seen comments from guys who fly in Europe who have to do it much more often.

Since it's impossible to test the autoland of all the different planes I would either leave it as is or make it an option the user can supply.

Andre

[Travis]

Hi Andre,

I've defined the default value as 1000fpm, and I've added (yet to test) an aircraft override. I'd like to eventually have an airline override too, but I need to make baby steps for a while here. So no GUI editing for the foreseeable future.

Best,

[alaskanflyboy]

Nov 21, 2019 14:17:29 GMT -5 Travis said:

What fpm rate would you judge to be a minimum for an inspection call?  I used 1000fpm as a placeholder - that sounds pretty hard to me.

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Is there anything else we should consider to call for an inspection?  Should smaller aircraft like your Cadet or a Skyhawk be judged at a different (less?) rate than airliners??

[/quote]


Realistically, it's not the decent rate in FPM that is the killer as faster forward speed makes less an angle of impact at the same descent rate.

Gs at impact are a more direct factor as I recall in damaging the aircraft, and even that will matter more on the strength of the airframe and the dampening effects of the landing gear. I know the some track Gs, but I don't know how reliably calculated they are or if they factor in on landing in the sim.

[Travis]

I missed this thread last evening....

I've added a GForce capture element, so we can look at various elements and conduct some tests. From smooth landing tests to near-crash landing tests that is.

The one aircraft which this would be useless on is the Majestic Q400. They do their own GForce measurements, and over the first few years of use, I've found them to report what I would call, "shockingly varied numbers."

Best,

[alaskanflyboy]

Nov 30, 2019 15:56:31 GMT -5 Travis said:

I missed this thread last evening....

I've added a GForce capture element, so we can look at various elements and conduct some tests. From smooth landing tests to near-crash landing tests that is.

The one aircraft which this would be useless on is the Majestic Q400. They do their own GForce measurements, and over the first few years of use, I've found them to report what I would call, "shockingly varied numbers."

Best,

Since it's modus operadi to allow opt-outs/ins I don't see the Majestic bird being a detractor. I also would say for the sake of landing impacts, if G-force indeed even spikes on touchdown in any of the sims, it might work to use the sim's g-force measurement even with the Majestic Q400.

[Travis]

Hi John,

Here's a screenshot of what the FCDU will look like on rollout....

That line will appear in yellow and red if the values exceed expectations.

We normally have only checked GForce while in the air, and we maintain a rolling average to smooth out any 'bumps,' plus we have the option to 'dampen turbulence' included. So I need to make some changes so that at touchdown (and after a runway overrun!) non-dampened non-average numbers can be returned.

(The Majestic doesn't use the simulator's flight engine, so the GForce AVAR is at a constant level. I want to think there's another 'high-fidelity' aircraft which does likewise, but I can't recall which one.)

Best,

[Travis]

I want to add that despite not being able to have easy-to-use GForce values for a small set of aircraft, I'd like to go ahead with allowing GForce to be a deciding factor in calling for aircraft inspections.

I just need to get good figures. One of my landings recorded a GForce value of 0.9862. (!!) That was an averaged and dampened value though.

Once I have it working to my (possibly ignorant) satisfaction, I'll update the Alpha 2 build.

Best,

[Travis]

Here's the results of a landing in a Carenado C208 in P3D4 (my earlier screen was from a VirtualCol Saab 340 in FSX):

It was a sharp landing (VSpeed-wise) but not too bad (or so I thought).  The GForce seen here (3.1274!!!) was the single instant non-dampened, non-averaged value.  The averaged and dampened GForce value for the second leading up to the point of landing was 1.1536. (The averaging lasts for 18 ticks - one second.)

I'll next try an averaged but not dampened value using the same aircraft back in FSX.   If luck holds, I'll make that flight later in my evening.

As soon as I can find a decent method for display - the Landing GForce values are currently not tied into the Inspection routine... for now they're just for display and logging - I'll update Alpha 2 so more Captains can begin testing.

I would really need everyone's FCDU logs to help me make better decisions.  I don't have FS9 installed, but I do have the FS9 Caravan Amphibian in use in my FSX.  So once I can make comparisons of similar apples, I can begin to bolt down a good model. 

Best,

[Travis]

I've had some interesting short test flights since my last post!!

In my "try it in FSX" flight, I was flying in near-to-CATI conditions. (The ceiling was 800 ft.)

I don't have global AI in P3D4, so that earlier flight went fine. But in FSX - with AI - a Beech 1900 collided with me just before IAP. (Its tail hit my ceiling because my altitude was lower.)

The collision didn't affect my aircraft because I don't allow SimConnect Collisions to damage my aircraft's systems. (But I did get an Inspection Hold after landing.)

So I just throttled back and maintained my glideslope and let the "aggressor Beech" to carry on and land first.

My Active Sky weather was still in a 'pea soup' condition.

Then about 500 AGL, when I had broken through the clouds, I saw the Beech turning off the runway. So I proceeded....

About 300 AGL, what had to be the Active Sky "Wake Turbulence" took ahold and I was slammed into the ground!!

As in all MSFS simulators, I began to bounce.

When I stabilized on the runway and began my rollout, I had 1400+ fpm vertical speed... and 0.9843 GForce. That didn't make any sense....

Now I need to step away for a few days to deal with real-world chores and things.   But I'll be thinking on a way to eliminate "negative-G landings" which even though that's what the sim reports, can't happen....

Best,

[Travis]

Dec 5, 2019 19:38:41 GMT -5 Travis said:

Now I need to step away for a few days to deal with real-world chores and things.   But I'll be thinking on a way to eliminate "negative-G landings" which even though that's what the sim reports, can't happen....

After a good night's sleep, I've come up with a cunning plan. I'll hope to run a couple of short tests by the end of my Saturday.