Questions about landing in the snow:

How deep is too deep, and what's the best way to determine how the depth of snow? Does the safe depth vary with weight and CG? Obviously floatation (tire size) is a big factor?

Are deep tracks freezing solid overnight something to worry about, when taking off the next day?

School me up please.

Love the thread title! In for the scoop on snow-wheeling as well.

Gump

I'm a big chicken when it comes to landing in snow on tires, unless I'm able to observe the snow depth and condition from the ground first. We get a lot of windblown crust on top here, which can ruin your day in a hurry (even if you're just landing in a snowed-in two track road). My rule of thumb is "the snow is always deeper, and in worse condition, than it looks from the air."

I've rarely been wrong when following that maxim, so my other rule is "don't land in snow any farther away than I want to snowshoe home."

Like I said...big chicken here.

So many variables...... anybody giving advice on the subject is just asking for trouble! What is great in the morning may tip you over a few hours later, or the other way around. My big fear is, while still on the summer time 29's, I end up landing on some snow very early in the winter, this is before I switch over to the 8:00's with the wheel skis. If I ever flip while on wheels, with a perfectly good set of wheel skis in the hangar, I'll feel like the worlds biggest dumb ass! Really, REALLY treat the subject with extreme caution, as there is no hard and fast rule as to what works.

Simple solution: Hire someone with a helicopter to fly you to your proposed landing site. Carefully examine snow conditions there. Is it more than a couple inches deep, don't go. If it's crusty, don't go. If it's slushy, don't go. If it's less than four or five inches deep, and pure powder, have your helo pilot IMMEDIATELY fly you back to your plane, get in and fly to your newfound landing zone.

Or, buy a set of skis and do it right.....you'll still get stuck occasionally, but at least it'll be right side up....usually.

MTV

Thus the question, I don't think there's a one-line answer
Surely someone here has experience of what is safe?

I have landed in patchy snow before, and snow about 1" deep. Both times it just felt like making a normal landing. I guess there will be about 2" of snow this time around, melting rather than crusting up. It is too thin for skis and wont last long enough to get in and out before it melts. We never get powder, always wet crap. Besides, I don't have a ski rating.

I imagine a thin layer (<3") of wet melting snow behaves much like 'hydroplaning the wheels' at first? Then you drop in as you slow down? Or is it more of a grabby surface?

Gump's picture clearly shows why very deep snow / nosewheel aircraft / small tires is a bad combination. Looks like that thing flipped over in about a 1/2 second after the nosewheel touched down.

To be clear, I am not interesting in pioneering spots with 6" or feet of snow.
I want to know where it starts to get risky. 2, 3" I can't see being a problem with tundra tires. A little more, well I wouldn't go near it (except maybe to try judge the depth?).

Unless you're at your LZ on foot at the exact time you want to take off or land, you CAN NOT judge the depth, firmness, or characteristics of the snow. From the air.... You can't tell shit, other than there's white stuff on the ground. Make a low fly-by to "test" the snow by dragging your wheels.... See the pics above.

Play in the snow on wheels, you end up upside down. Some of the best airplane drivers on this site have learned that lesson the hard way. Bushwheels won't help you either.

Gump

Ok, so when broken terrain allows you to clearly see the depth of the snow from a close fly-by, how deep is getting too risky to land?

If you did land in snow just fractionally too deep, how would the aircraft react?

I am assuming you guys in AK still fly the fringe-seasons, and have to deal with thin melty snow cover from time to time.

Battson wrote:Ok, so when broken terrain allows you to clearly see the depth of the snow from a close fly-by, how deep is getting too risky to land?

If you did land in snow just fractionally too deep, how would the aircraft react?

I am assuming you guys in AK still fly the fringe-seasons, and have to deal with thin melty snow cover from time to time.

Apparently, you prefer not to listen to the answer.

Read what Gump wrote.

Anything else, and you're a test pilot. How does you're insurance company feel about that?

There is NO WAY to safely evaluate landing in snow from the air. Not to say it hasn't been done safely, but the pictures Gump posted tell the story of what happens if you misjudge. And that was a nose wheel airplane....think a tailwheel would have stayed upright? Not hardly. And that is not deep snow.

MTV

Oregon pilot association uses these... (4) located at Beaver Marsh about the middle of the runway.

(If you are a snow Haole, be very careful anytime you deal with snow!)

mtv wrote:Apparently, you prefer not to listen to the answer.

Read what Gump wrote.

Anything else, and you're a test pilot. How does you're insurance company feel about that?

There is NO WAY to safely evaluate landing in snow from the air. Not to say it hasn't been done safely, but the pictures Gump posted tell the story of what happens if you misjudge. And that was a nose wheel airplane....think a tailwheel would have stayed upright? Not hardly. And that is not deep snow.

MTV

Mike, no need to get short about it...

A little context: I know a lot of guys who are landing in snow regularly, every winter. We don't get enough for skis mostly, so it's part of doing business for some. I know one guy who's flipped once, when it was just too deep like Gump's example, and another couple who have skidded off. The rest do fine and have done for 35 years +.

Because rest seem to do fine, I was looking for someone with experience, to tell me how to stay safe. I take your points on board, that is why I asked, but I have additional questions also. I respect your decision not to risk it yourself, but many others do it successfully.

Especially if you've been to a place before, if the snow sits atop a rock or post, with vertical sides, you can see the snow depth like a cut-away cross section. I have used this method before, I wish I had all my photos uploaded to show the example. Of course that only really works with a fresh fall, which is kinda all we ever get here (it disappears so fast). I appreciate you can't get a feel for the condition of snow until it is too late. I was interested to hear about other ideas, and I understand there are none?

To be clear, I am only thinking about a little snow (hard to see but there was a steady 1" on the airstrip):


Not a lot of snow (in my books, lookes like 3" on the tires), but it doesn't seem to bother some people I know:


Hopefully that helps?


BTW, I am officially approved as a test pilot right now. I am insured for it too. The underwriter didn't even increase the rates. No kidding.

If I know my landing surface intimately... Gravel runway for example, with state snowplow keeping it bladed off, or a flat chunk of ground I know is suitable, I will play in maybe 2-3 inches of fresh snow for landing. For take-off maybe a bit more if I walk off the strip to see how it feels.

But an unknown surface with no idea of what's covered up, or snow that's drifted and had a chance to harden up. No way. Get into a crust, or a drift not seen in flat light, you have an instant problem. And anything more in depth than just those few inches there is way too much drag, and you're stuck.

Gump

Thanks Gump, that is real good advice.

Also, adding to my "fear" list is ...

frozen (icey) snowmachine tracks covered by some fresh powder. The big snowmachines can really leave some deep ruts.

Here's one way to evaluate snow for landing.....




But the only way to do it long term and safely is to be damn careful and even more lucky.



Does that look deep?????

I'm with Gump. I don't mind taking off in 4-5 inches on my packed dirt strip, but landing on more than 3-4 makes me nervous, even on 29s. If you have any variation in the terrain, windblown snow over a rut/ditch/culvert makes the danger completely invisible.

Landing on a snowy road might also look easy, but it can quickly turn into a pucker fest as you sit there and wonder if you're going to get it shut down before you slide off into the much deeper borrow pit on one side or the other. Forget directional control in that situation, you only have a directional vote, at best. The average crown on most dirt roads is enough to start you sliding sideways, especially if there is any crosswind. Don't ask me how I know.

Another factor which I stupidly failed to consider one time was how much more takeoff roll was required to get out of a few inches of wet snow. A lot. I'm lucky to still be here after that particular rodeo.

An inch or two of patchy snow is one thing, but more than that--especially if the ground is fully blanketed/you're unfamiliar with the terrain underneath / and/or you've had any changing wx since the snow fell--and I revert back to being a chicken pretty quickly. Things seem to go south on snow much faster than on terra firma, and where I live it's often below zero when they do.

UtahMaule wrote:Does that look deep?????

Judging by the tail fin, it looks about 6" or so

That is more than I would ever plan on messing with. Seems like if you can't see ground through it, it's always too deep to risk it.

RanchPilot wrote:An inch or two of patchy snow is one thing, but more than that--especially if the ground is fully blanketed/you're unfamiliar with the terrain underneath / and/or you've had any changing wx since the snow fell--and I revert back to being a chicken pretty quickly.

Totally agree.
Good to hear about your road experiences too, there is a track I could also be landing on, so that is good to know.

Glad to share in your experiences, I am fast gaining a healthy fear of landing in blanket snow cover.

Battson,

Sorry if I came across as short. I for one have screwed the pooch on a snow landing, because in the conditions ambient it simply wasn't possible to evaluate the situation and the surface, AND I wasn't bright/informed enough to realize that.

I've landed on wheels in snow, and on snow a good bit on skis. I tell folks that ski flying is the most fun you can have in an airplane.....but, if you play in the snow enough, you're going to break something.

I was lucky and just broke an axle, but I've also slept out a couple other times I'd really rather not have because I misjudged snow conditions. I can build a one person shelter in record time now, so I'll probably never get stuck again.....yeah, right!

MTV

I can't remember the source right now, but I was just reading an accident report of a C-180 wheel plane that flipped in snow here in AK. Apparently the pilot did a low pass on a remote strip and thought he saw gravel showing through. He discovered upon coming to an (upside-down) stop that what looked like gravel from the air was actually stove ash spread by locals to hasten melting, on top of about two feet of snowpack.

[edit: here it is: From the BAS testimonials page]

Incident occurred at Shell Lake, approx. 80 NM NW of Anchorage. I was the only person on board. Approx. 3 1/2 feet of snow with a 1000' stretch with freshly-strewn fireplace ash, cinders, and dirt, apparently spread to melt the snow faster. Looked like gravel showing through a few inches of rotting snow!