Simviation Forum - Harder landing in snow conditions?

Mar 16^th, 2012 at 9:19am

Gregorio Offline
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Sao Paulo, Brazil

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Posts: 40

I recently pulled up my FSX in a little spare time I had and set up a flight from UUDD to UUDL jsut for fun. I was using the PMDG 737NGX and REX as the weather engine. I asked REX to to use the real-world weather and it turned out to be a very snowy, cold day. Nonetheless, I set up the plane and went for the flight. Everything went well up until my final approach, where I made a call and would like my fellow virtual captains - or any real captains that may be around - to weight in if possible.

In FSX, UUDL does not have much to help one land as far as I could check. So I used my FMC route to get near the airport, but if I kept following the FMC it woud take me directly to the middle of the runway at an angle. So I switched to heading mode and flew a base leg by deviating from the FMC course while still following my descent plan, and made a turn to final using the runway heading (I was going for RWY05). By the time I saw the runway, I also realized that the descent would have to be a bit steep (around 1200-1300 ft/s) if I wanted to complete the landing. For a second or two I though about aborting the final approach and re-try the landing, yet I though this could work to my advantage. My reasoning was as follows.

1) The snow was strong. The runway is most like slippery.
2) I had some left/tail wing too (needed a bit of crabbing).

So I though that, by descending a bit steeper and flaring a bit earlier I could get the plane to land a bit harder, which would make the tires have more attrition with the runway (by the sheer force of the harder landing) and that would help in making sure the breaks could stop the airplane in a snowy/wet/tailwind situation. So I aimed the plane at the very beginning of the runway, descended around 1300 ft/s, set my autobreaks to MAX, and when close to it I pulled the yoke and reduced my vertical speed to around 700-800 ft/s and touched the rynway at the right spot.

I know, this is a simualtion and I don't think that FSX takes into account things like runway attrition coefficient, break efficiency given multiple weather variables (inserted by an external program by the way), and so on, but I wanted to make the right decision taking those factors into account.

The question is, what do you guys think? Was this a good call? Shoud I have tried a different landing? Any feedback is welcome.

Thanks!!!!

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Reply #1 - Mar 16^th, 2012 at 11:31am

Strategic Retreat Offline
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Another thing FS doesn't keep track of is icing. Theoretically it is possible to equip a plane with a VERY rough and incredibly limited icing capability under FS, but even this little is EXTREMELY rarely seen. I'd guess because not all coders of planes like to add a difficult matter like icing to their planes. The users may not like it, and so...

And so... not always the behavior of planes under FS mirrors the behavior of planes in Real Life, especially in certain conditions...

If you were landing under a strong snowfall...

...I'm sorry, but this is one place where your flight departs from reality, as if the snowfall is really strong, the airports subject to it are usually closed.

If there was strong snowfall, the right call would have been to divert to a different airport, because flying under heavy snow conditions makes easier for ice to accumulate on the flying surfaces, making the flight inherently more ~~dangerous~~ deadly.

The planes' anti-ice systems have a finite capability of keeping ice at bay. Freezing cold coupled with the humid nature of snow can easy overcome the anti-ice system of any planes in a lot of situations. This is why if it gets too much, every flight gets suspended in the airport under snowy onslaught.

And what I wrote above doesn't keep track of the possibility that the runway could have been contaminated by a huge amount of fallen snow that would have played havoc with your landing.

The fact that FS does not give you those variables does not mean you don't have to keep them in mind. If you allow the supermassive holes in the realism of FS to cradle you into a feeling of false security, making you say, "who cares... it isn't simulated anyway...", you're simply playing with a game, not using a simulator. Lips Sealed

There is no such a thing as overkill. Only unworthy targets.

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Reply #2 - Mar 16^th, 2012 at 4:43pm

Gregorio Offline
Colonel
Sao Paulo, Brazil

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Posts: 40

Thanks for the idea. Yes, I considered the airport closed scenario and the diversion, but as I said, it was one of those spare time flights between the longer ones where I sit down with the manuals to plan. I also had only the time to a short flight so when I saw myself in the situation, I just assumed that it was under the operational limits and landed. But then again, if it were under normal parameters, I guess I would not need a harder landing, right? Well, fllying and learning

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Reply #3 - Mar 17^th, 2012 at 2:53am

GlobalHobo Offline
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I Fly ORFAir

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From a real-world airplane driver: No, that was not the way you'd set things up in the NG (or any other real-world airplane.) A lot of Russian airfields are minimally equipped for IFR conditions (I don't have extensive experience in Russia, but enough to know that it can be quite a different experience than flying in western Europe or North America), so now you know one reason why Russia tends to have more crashes than other parts of the world. Russian pilots as a group are as good as anyone, but some of the older ones still think that they can make stuff up as they go along. But I digress.

So, basically you want to fly a normal approach and landing and let the anti-skid do its work, even on an icy runway. Flying down in Antarctica, the runway WAS ice. You'd be amazed at what a functioning anti-skid system will cope with if you keep it within operational parameters. Trying to drive the mains through the top of the wing will NOT improve braking action!

If there are no charted approaches, it's easy to build a visual approach in the FMC, something the PMDG FMC replicates extremely well. It's a little too complicated to explain here, but I'm sure you will find something about building waypoints in the PMDG documentation, or else invest a few bucks in Bill Bulfer's FMC User's Guide. I keep it in my flight-bag to prep for sim-checks and for help with operations I don't use on a regular basis.

In a nutshell, the procedure is to extend the runway centerline out three to five miles and build a few lead-in L-Nav/V-Nav points. Then you can either fly a coupled approach using the auto-pilot or hand-fly with the aid of the flight-director. You've got to plan ahead for this, though. It's not something you do while you're zipping around the pattern. And if you can't complete the landing using a normal, stabilized approach, go around. If you're high, come back around with a better set-up. You can get away with an abnormal approach in MSFS sometimes, but in the real world, that usually results in bent airplanes at least, and dead people at worst.

I can understand your confusion, though. Not a whole lot of snow in Sao Paulo. One of the reasons I have enjoyed my visits there. The warm weather and the *a-hem* delightful "scenery." Wink

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Reply #4 - Mar 18^th, 2012 at 10:23pm

-Crossfire- Offline
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Northern Canada

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Strategic Retreat wrote on Mar 16^th, 2012 at 11:31am:

If you were landing under a strong snowfall...

...I'm sorry, but this is one place where your flight departs from reality, as if the snowfall is really strong, the airports subject to it are usually closed.

If there was strong snowfall, the right call would have been to divert to a different airport, because flying under heavy snow conditions makes easier for ice to accumulate on the flying surfaces, making the flight inherently more ~~dangerous~~ deadly.

The planes' anti-ice systems have a finite capability of keeping ice at bay. Freezing cold coupled with the humid nature of snow can easy overcome the anti-ice system of any planes in a lot of situations. This is why if it gets too much, every flight gets suspended in the airport under snowy onslaught.

And what I wrote above doesn't keep track of the possibility that the runway could have been contaminated by a huge amount of fallen snow that would have played havoc with your landing.

The fact that FS does not give you those variables does not mean you don't have to keep them in mind. If you allow the supermassive holes in the realism of FS to cradle you into a feeling of false security, making you say, "who cares... it isn't simulated anyway...", you're simply playing with a game, not using a simulator. Lips Sealed

Sorry mate... gotta call you on a couple things here...

Flying through snow (heavy or light) generates the least amount of airframe icing compared to other icing conditions. All you get is a little impact snow on the leading edges, nothing to worry about.

Maybe some airports close during heavy snowfall... but in Canada, it's business as usual, albeit with delays. Winter ops just takes longer, for obvious reasons.

We fly the King Air into short strips, at night, in snowy conditions, somtimes in 2 miles vis... or less. Oh ya, and to land, you have to do a circling NDB approch. And some of the airports dont have PAPI's. Wink

It makes for some challenging flying. As for landing in snow, it sure does make your landings softer.

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Reply #5 - Mar 19^th, 2012 at 7:56am

Gregorio Offline
Colonel
Sao Paulo, Brazil

Gender:
Posts: 40

@GlobalHobo Thanks!!! Really appreciate the feedback. Yep, I've built some waypoints in the PMDG's FMC before. In the end, what prompted the situation I found myself on was lack of planning. Again, it it was a quick flight and it was still fun to do. But I'm glad that it helped me learn and improve my simmed-flight technique

And yes, there is no snow in São Paulo. Never. Actually we are having a very hot summer this year and, albeit a bit windy sometimes, the days seem to be beautiful for VFR flights. Maybe one day I'll get up there as a real pilot.

@ALL Thank you all for your feedback. Really appreciated!!!

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Reply #6 - Mar 19^th, 2012 at 4:56pm

Strategic Retreat Offline
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-Crossfire- wrote on Mar 18^th, 2012 at 10:23pm:

Sorry mate... gotta call you on a couple things here...

Flying through snow (heavy or light) generates the least amount of airframe icing compared to other icing conditions. All you get is a little impact snow on the leading edges, nothing to worry about.

Maybe some airports close during heavy snowfall... but in Canada, it's business as usual, albeit with delays. Winter ops just takes longer, for obvious reasons.

We fly the King Air into short strips, at night, in snowy conditions, somtimes in 2 miles vis... or less. Oh ya, and to land, you have to do a circling NDB approch. And some of the airports dont have PAPI's. Wink

It makes for some challenging flying. As for landing in snow, it sure does make your landings softer.

I know. I never said there is no way to fly in snowy condition, or Alaska and Siberia would be off limits always. Wink

Please notice in my message the specifier "heavy" snowfall. The kind of icy snowfall that in less than a hour can mess-up every kind of communication routes, the kind that in three continuous hours of falling can make even train tracks impracticable (the kind happened even here in Italy for a while, this February, on some places... Italy was unrecognizable from the satellites for a good part of last month).

And, I specified too, the problem is not exclusively at the flight stage. Under a heavy snowfall can be difficult if not outright impossible to remove the snow that falls on the runway until the snowfall abates. I suppose, if your gear malfunctions, belly landing on a snow-covered runway can be better than a belly-landing on a completely dry and non-contaminated runway (less probability of a fire starting because of sparks caused by metal dragged on tarmac), but this is a rather extreme scenario... and ruining purposefully your landing gear on an ungodly tall snow deposit on the runway so you can relatively more securely belly-land on the snow is not what a good pilot should plan to end the current flight (at least if s/he has the choice to land elsewhere, where is safer). Grin

There is no such a thing as overkill. Only unworthy targets.

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Reply #7 - Mar 19^th, 2012 at 7:15pm

DaveSims Offline
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Clear Lake, Iowa

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Strategic Retreat wrote on Mar 19^th, 2012 at 4:56pm:

-Crossfire- wrote on Mar 18^th, 2012 at 10:23pm:

Sorry mate... gotta call you on a couple things here...

Flying through snow (heavy or light) generates the least amount of airframe icing compared to other icing conditions. All you get is a little impact snow on the leading edges, nothing to worry about.

Maybe some airports close during heavy snowfall... but in Canada, it's business as usual, albeit with delays. Winter ops just takes longer, for obvious reasons.

We fly the King Air into short strips, at night, in snowy conditions, somtimes in 2 miles vis... or less. Oh ya, and to land, you have to do a circling NDB approch. And some of the airports dont have PAPI's. Wink

It makes for some challenging flying. As for landing in snow, it sure does make your landings softer.

I know. I never said there is no way to fly in snowy condition, or Alaska and Siberia would be off limits always. Wink

Please notice in my message the specifier "heavy" snowfall. The kind of icy snowfall that in less than a hour can mess-up every kind of communication routes, the kind that in three continuous hours of falling can make even train tracks impracticable (the kind happened even here in Italy for a while, this February, on some places... Italy was unrecognizable from the satellites for a good part of last month).

And, I specified too, the problem is not exclusively at the flight stage. Under a heavy snowfall can be difficult if not outright impossible to remove the snow that falls on the runway until the snowfall abates. I suppose, if your gear malfunctions, belly landing on a snow-covered runway can be better than a belly-landing on a completely dry and non-contaminated runway (less probability of a fire starting because of sparks caused by metal dragged on tarmac), but this is a rather extreme scenario... and ruining purposefully your landing gear on an ungodly tall snow deposit on the runway so you can relatively more securely belly-land on the snow is not what a good pilot should plan to end the current flight (at least if s/he has the choice to land elsewhere, where is safer). Grin

Have you ever seen the equipment airports have for snow removal (http://www.oshkoshairport.com/en/SnowTrucks.aspx)? ; Very, very rarely does a snow shut down an airport, as we (yes we, I happen to plow snow on airport) are plowing from the first flake to the last, never allowing much to accumulate.

You also need to get some real world experience about snow/ice accumulation on aircraft. Snow does not lead to ice on the aircraft, does not stick to the aircraft, and does not usually affect flight operations much other than low visibilities and possibly slick runways. Freezing rain and freezing fog are what cause ice to accumulate, and are very dangerous even for the largest and best equipped aircraft.

Dave

www.flymcw.com

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Reply #8 - Mar 19^th, 2012 at 11:39pm

GlobalHobo Offline
Colonel
I Fly ORFAir

Posts: 124

Quote:

In the end, what prompted the situation I found myself on was lack of planning.

That, sir, is one of the best lessons anyone can learn, whether the flying is simulated or real: The better the planning, the better the flight. Goes for everyday life, too. Doesn't eliminate the possibility of something wierd happening (A Yeti on the runway perhaps?), but you're better prepared to handle it if it does.

Keep the shiny-side up. Tchau!

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Reply #9 - Mar 22^nd, 2012 at 12:18am

Strategic Retreat Offline
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DaveSims wrote on Mar 19^th, 2012 at 7:15pm:

Have you ever seen the equipment airports have for snow removal (http://www.oshkoshairport.com/en/SnowTrucks.aspx)? Very, very rarely does a snow shut down an airport, as we (yes we, I happen to plow snow on airport) are plowing from the first flake to the last, never allowing much to accumulate.

Not everywhere there's the same equipment. While advanced equipment is expected in airports where the snow falls copious and frequently, there are a lot of places in the world where the investment of one or more of the more capable of those machines (I remember to have seen one in TV that blew fire on the tarmac to melt ice, in use somewhere, too) is hardly justified.

You cannot really justify the expense of various hundreds of grands -- be them dollars, euros or pounds -- on a machine that you will use once every decade, if even.

And in those airports (see the various center Italy ones to get an idea), when the snow, that time every decade or so, decides to hit... snow may overrun the machinery. Especially when snow hits hard like this year... nothing like it was remembered ever since 1942... when this happen, and not only here in Italy, things get stuck for a while. Airports must close to allow for better weather that's allow for snow to be carted out of the way.

Last minute buying a larger snow-plow does hardly work, you know. Especially when they cannot deliver it to you because the airport is jammed by an exceptional snowfall.

DaveSims wrote on Mar 19^th, 2012 at 7:15pm:

You also need to get some real world experience about snow/ice accumulation on aircraft. Snow does not lead to ice on the aircraft, does not stick to the aircraft, and does not usually affect flight operations much other than low visibilities and possibly slick runways. Freezing rain and freezing fog are what cause ice to accumulate, and are very dangerous even for the largest and best equipped aircraft.

Are you saying that snow doesn't ice up an aircraft? At all? Under heavy fall condition even? Ever? Huh

Man, they do not make snow like in the past anymore, nowadays. Roll Eyes

Sorry, but while I may be read as over-dramatizing it, you are trying to balance things by over-downplaying it. Let's find a middle way, ok? While I am aware that is water in suspension on freezing cold metal that is the main carrier for planes icing, you cannot simply blow away the effects on the planes of snow in heavy fall conditions with a shrug, the way you seem to be doing. Tongue

There is no such a thing as overkill. Only unworthy targets.

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Reply #10 - Mar 22^nd, 2012 at 2:45am

-Crossfire- Offline
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Northern Canada

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Strategic Retreat wrote on Mar 22^nd, 2012 at 12:18am:

Are you saying that snow doesn't ice up an aircraft? At all? Under heavy fall condition even? Ever? Huh

In flight... it doesn't, on the ground, in the right conditions, obviously... yes.

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Reply #11 - Mar 22^nd, 2012 at 8:13am

garryrussell Offline
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Hello!

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Driving a car in heavy dry snow, sometimes you don't even need the wipers because the snow blows up and over the car without hitting the windscreen, so doesn't accumilate mich on a moving object

If it's wet snow then it does hit but that tends to slide off surfaces rather than ice up

I've known the local shut a few times in heavy snow, not due to ice but simply because the visibilty drops below limits.

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Reply #12 - Mar 22^nd, 2012 at 7:12pm

DaveSims Offline
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Clear Lake, Iowa

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Strategic Retreat wrote on Mar 22^nd, 2012 at 12:18am:

Are you saying that snow doesn't ice up an aircraft? At all? Under heavy fall condition even? Ever? Huh

Yes, snow may accumulate on top of the aircraft surfaces while it is sitting on the ground. However if usually does not stick. I will use my snow plow as an example. Before we start plowing, we usually start up our plows and park them outside of their heated buildings. This is not to warm up the engines, but to cool down the windshield and snow plow blade. Once the surface is cooled below 32F (0C), the snow does not melt and refreeze to the surface, it simply slips off. This helps prevent ice buildup on the windshield and on the plow blade.

Since the aircraft is usually outside, the skin is already below freezing, so the snow does not stick. Ice on aircraft is caused by the skin of the aircraft being below freezing, but the moisture, in the form of cloud or freezing rain, is still mostly liquid in nature. This causes the ice buildup that can be dangerous to aircraft.

As I mentioned before, the biggest issues snow events create for aircraft operations is limited visibility, and potentially contaminated runways. Yes, I do realize there are airports out of the snow belt that are ill equipped for the unusual snow fall. I used to work at one. Our "snow plan", which all US commercial airports big and small must have one, simply said in the event of snow, close the airport and come back tomorrow when it melts. Wink

David Sims
Airport Operations Supervisor/ARFF Training Officer
Mason City Municipal Airport

Dave

www.flymcw.com

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