You can't tell snow depth from the air

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pelmet
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You can't tell snow depth from the air

Post by pelmet »

Learned that long ago but was lucky. This guy wasn't.

The Cessna 152, C-GZLF, was on a flight from St. Andrews, MB to Lac du Bonnet, MB. The pilot conducted a low pass before landing to inspect the runway. On touchdown, the aicraft encountered snow up to 12 inches in depth. The aircraft veered left to the edge of the runway, struck a snow drift, and overturned. The pilot and passenger exited without injuries. The aircraft sustained substantial damage to its wings, tail and propeller.
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iflyforpie
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Re: You can't tell snow depth from the air

Post by iflyforpie »

That's why you phone ahead for an RCR.

Just curious what people's personal limits are in snow on wheels? I've done four inches of powder and I've never gone through any drifted snow.
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Meddler
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Re: You can't tell snow depth from the air

Post by Meddler »

Depends on the type of ac. Ive landed and departed in probably 8 to 10 inches of fluffy stuff, with no tracks in it. A drift or crust would be a different story. That was in a light 182.

And no, Im not saying 10" when I mean 4. :mrgreen:
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pelmet
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Re: You can't tell snow depth from the air

Post by pelmet »

Remember something, if you have used your brakes, you have created heat. Now you melt some snow and you risk one or more frozen brakes on landing which can have very bad consequences.

Has anybody ever pushed a Cessna around on a very quiet day and you are near the wheel. It has been my experience that you can sometimes hear the disk rubbing against the pad. Maybe this always happens, I don't know. But rubbing creates heat. Is it a lot, I don't know but I wonder if brakes heat up a bit while taxiing even if no brakes are being used. If so, depending on the conditions, maybe there will be some melting then freezing depending on the OAT, amount of rubbing and taxiing distance.

I'm sure the Colonel can tell us a bit more.

I did see frozen brakes once in a King Air after doing one on the taxiing and taking off in dry snow. Had 30 degree left and right on landing and two tires with flat spots. The captain claimed that he had not used any braking while taxiing out but he was the kind of guy that might not tell the truth.

King Air's apparently are prone to frozen brakes. Apparently there are some with bleed air heating to the brakes.

Watch out for the drifts or deeper areas as well. On time I spent quite a while driving up and down a runway in a borrowed car to try and pack down the snow. It was only perhaps 4 inches but I didn't want frozen brakes.
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Re: You can't tell snow depth from the air

Post by PilotDAR »

Snow flying should get dual training all its own, there's so much to know...

I've done 8" of loose snow on wheels in the 150, but there are tricks to keep it safe. If you're maneuvering on loose snow on wheels, don't use the brakes at all, so they stay cool, as noted. If you must use one, lock it right away, as a locked brake will not develop heat. If it's that snowy, sliding a tire will not be a problem. Before you begin the takeoff, look at the wheel (presuming you can see it). If there is ice and water drops around the brake caliper, taking off would be unwise, until the brake is clear and dry.

If you think that you have frozen a brake and your next landing is to be on a friction surface, plan to touch and go, while to touch a wheel and test that it turns, instead of drags. Yes, if you land on dry pavement with a frozen brake, you're going to burn right through a tire, as you probably slide off to one side. If this is a risk you expect, carry a few of those little gas line methyl alcohol bottles in the plane. Pour one half and half over each brake, and you'll get airborne okay. Once up, try to watch each wheel spin down, if it's doing that, it's not frozen, and you're okay. If you think you froze a wheel, plan to land on a slippery surface - to apply your alcohol, before the paved runway landing. I have had to do this a number of times.

If you're going to land on unbroken snow on wheels, either KNOW the depth and type of snow, or don't land. Again, there are tricks, but they are beyond the scope of presenting on a public forum. DO NOT land wheel planes on snowmobile tracks. They look inviting, but if a snowmobile made a track the snow is not dense enough to support a plane, and you will be stuck. If the snow could have drifted, be alert to the possibility that there are alternating firm and fluffy spots. This will make for a very unpleasant ground run - I did this once in an Aztec, and the PIO which resulted was nearly a problem for me.

If you are landing un unbroken snow, which you are satisfied is suitable, remind yourself that the view of the surface might be like a glassy water landing - you cannot tell how high off you are - no texture. Plan a dragged in soft field type landing, so if you touch before you expect, you're already in a flare attitude. If you cannot do this (short length or skill concerns) don't attempt to land there. This is where snowmobile tracks can be useful. While not landing on or across them, you can land beside them, and use them to judge your altitude.

The fact the plane has enough power to land on a higher drag surface does not mean it has enough power to takeoff later. You can get stuck, not because you cannot get the plane moving, but because you cannot get it moving fast enough to take off. drag increases as a square of the speed for both air, and snow! Keep your soft field takeoff skills sharp. When I land on uncertain surfaces, I will drag one mainwheel first in a touch and go. I'm used to how much drag I expect to feel with the touch - too much drag, like the plane swings to that side with the wheel touch, and I'm not going to land there at all.

If you are going to land on ice, take mountain climbing ice screws with you. They are vital if you should need to tie it down there (which you really do want to do, if you're going to leave it, and walk to shore). One such ice screw is also vital, should you need to tie the plane to hand or jump start it.

None of the foregoing addresses considerations of ice thickness and type on frozen lakes, that is a whole other subject.
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Meddler
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Re: You can't tell snow depth from the air

Post by Meddler »

"One such ice screw is also vital, should you need to tie the plane to hand or jump start it. "

What happens next? :roll:
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Re: You can't tell snow depth from the air

Post by Meddler »

Lots of questionable advice here I would say, if taken as gospel by a low timer. Mostly just don't land if you don't know the conditions. As for frozen brakes, I've never had much for problems in small Cessna s. If you think they might be frozen, pump them first and land firm.

Land on a slippery surface first? Where would one do that?
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Re: You can't tell snow depth from the air

Post by PilotDAR »

What happens next?
I recommend the same thing which would have happened if you had had problems starting the plane on a high friction surface - because you still tied it.
I've never had much for problems in small Cessna s. If you think they might be frozen, pump them first and land firm.
Yes, these two sentences link well.

If, however, you have had problems with frozen brakes on small Cessnas, you'd probably have found that pumping them is of no use to unfreeze them. Landing firm might snap them loose, or, might cause a locked wheel to slide the tire down a runway and melt a flat, if you can keep it straight. Or, simply nose over your taildragger. Choosing to land on a slippery surface, like a grass runway you know well, would allow you to get the plane safely down, so you can free the frozen brake, perhaps with gas line antifreeze you wisely carried for the purpose. Then you can takeoff and fly onward to the dry paved runway you were originally headed for. I have certainly diverted to grass to assure that I did not land on pavement with a frozen brake.

Any advice should be questioned by anyone using it - that's how we really learn - by thinking and questioning. My advice, as always, is worth what you have paid for it.......
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lownslow
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Re: You can't tell snow depth from the air

Post by lownslow »

I've never dealt with too much snow (RCRs are a great thing) but I always wondered about that 'don't use your brakes' bit. Could you do the exact opposite and get them good and hot to boil off any contamination?

LnS.
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Re: You can't tell snow depth from the air

Post by Shiny Side Up »

If one's wheels are turning as you leave the ground, you're unlikely to have any problems with having a frozen brake on landing. The main problem occurs with frozen brakes is if you're riding them heavily while taxiing, you stomp on one to turn around (applying hefty power) blowing snow over that now closed hot brake. So you find people turning in circles at the end of the runway when as they're trying to line up they can't unlock the one wheel. Other place is when people are doing run ups after riding the brakes, blasting a ton of snow into the brakes. Worst case is when some fool yanks on the park brake after riding the brakes while taxiing through the snow.

Not having frozen brakes is as simple as not riding them while you're taxiing. If you don't heat them up, snow won't melt on them and then re-freeze later. Don't stop if you're in the white stuff. Avoid making turns where you'll need brake. Which way does power help you turn?

The best advice about snow, is if you're not certain, don't challenge it. Even if you get a good report. Came in for landing one night, just after some fresh snow had fallen. Asked tower if it was clear, he said "no but there's only an inch or two". An inch or two turned out to be deeper than the Cessna's wheels, we didn't stick around to find out how deep it was.
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Re: You can't tell snow depth from the air

Post by Meddler »

I recommend the same thing which would have happened if you had had problems starting the plane on a high friction surface - because you still tied it.
Just trying to be funny. I like the image of someone slashing the rope and then scrambling into the plane before it slowly skitters away across the lake. :mrgreen:
a grass runway
Oh, the grass. Right. I was thinking winter.
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image.jpg (80.68 KiB) Viewed 5063 times
Im sure its down there somewhere...

All depends where you are I guess. There arn't many options when the snow is deep here.

And yes, all advice should be taken with a grain of salt. I guess I should nt worry that student pilots will actually try stuff they read on these forums. If they did there would be planes falling out of the sky at pretty regular intervals...
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Re: You can't tell snow depth from the air

Post by PilotDAR »

Several times, I have seen hand started aircraft toodling along the ice or snow on skis, as their sole pilot starter rushes to catch up to it, and get in to get control. One Taylorcraft got to shore first. Thus, the wisdom to tie the aircraft while you start it (Oh, also a TC reg) was reaffirmed. Rope to tail tiedown, through ice screw or around tree, whatever, and back to the cabin tied. once in the cabin, and in control undo rope, let it slip through the tie point, and off you go. If you work it out really well, you get your ice screw back too!

Yes, we have grass runways, and even in winter, they are still grass runway, which may have snow on them, and may have bare spots. With a frozen wheel, or on skis, I would much rather hit a bare spot on a snow covered grass runway, than a bare spot on a paved runway.

Like so many forms of information ('cause really books are not much different than the internet, just slower and with the risk of paper cuts) things which new pilots can read on the internet can be properly applied, misapplied, or applied by lesser skilled pilots who should not be applying them. That's up to the pilot to determine for them self. For myself, I do not post anything, which I would not train in person to a pilot of adequate competence for the aircraft type being flown. But the relevance of what I post is for the reader to decide, it makes no difference to me. I could repost passages out of flight manuals, and pilots could get into trouble with what is described, even though it was the best information for that aircraft. I have darn near had accidents doing exactly what a flight manual says, probably because my underlying training was not adequate.
It is still up to every pilot to seek out competent training on type and environment. But with some clues as to the training they seek, and then the competence trainer, skills can really be well grown.

Remember.. the first thing I wrote on the subject of snow flying in this thread?
Snow flying should get dual training all its own
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Meddler
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Re: You can't tell snow depth from the air

Post by Meddler »

Rope to tail tiedown, through ice screw or around tree, whatever, and back to the cabin tied.
Ah, now I follow you. Same as with a floatplane at a dock when you re not sure it ll start. You ll still have to explain how to get the ice screw back though. Im a bit slow on the uptake this am.
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Re: You can't tell snow depth from the air

Post by PilotDAR »

The Ice screw may be a loss. I've always got them back, when I was satisfied that the aircraft could be held by hand at an idle. But, if in doubt, would I rather risk loosing an ice screw or a plane? Easy choice, and having the ice screw gave me the choice! It's the same kind of thinking which generally has me landing enroute, if I think I might need fuel, rather than hoping I have enough to make it.... I know it's not as "white scarf" like, but who am I trying to impress?

I have also seen ice augers, and chainsaws, to cut holes in the ice, through which bits of 2x4 were submerged to act as a tie point. Equally effective, but a lot more work, and things to carry with you!

I was called one night a few decades back, by a not yet pilot friend, who told me that a mutual friend had left two 180's and one 185, all on wheels, parked on the ice. Big winds forecast for the next day, and no way to tie them down. Would I fly them out to a nearby airport for tiedown? So, two night departures off the ice (which had a lot of standing water, so spray everywhere). The third 180, we found could not be started for a mechanical reason. Okay, I'll saw holes, put 2x4's down the holes and tie it. I sawed the first hole through a few feet of ice, waiting for the spray of water. No water spray, instead, gravel! The ice went solid to the shallow bottom. We had to push the 180 well off shore, to find water deep enough to saw into, to place the 2x4's. We were done about 1AM, as the wind began to pick up.

So, now, I just carry three ice screws in each plane - much less effort!
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iflyforpie
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Re: You can't tell snow depth from the air

Post by iflyforpie »

An ice screw is $5.... cheaper than a call out or CAA membership.... assuming they would even come out to boost you.
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Re: You can't tell snow depth from the air

Post by Meddler »

Cool story. I wonder what the regs are for "night departures from frozen lakes with standing water". But ya, if frozen lakes are your thing, I can see how ice screws could be important.

Oh, hey! Did the brakes freeze up with all that standing water?
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Re: You can't tell snow depth from the air

Post by PilotDAR »

Did the brakes freeze up with all that standing water?
Nope, it wasn't below freezing!
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Re: You can't tell snow depth from the air

Post by Blakey »

Meddler wrote:
Rope to tail tiedown, through ice screw or around tree, whatever, and back to the cabin tied.
Ah, now I follow you. Same as with a floatplane at a dock when you re not sure it ll start. You ll still have to explain how to get the ice screw back though. Im a bit slow on the uptake this am.
That's easy. You're in the middle of the lake so you just hold onto the rope while you taxi around the ice-screw counter-clockwise a dozen times or so!
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Re: You can't tell snow depth from the air

Post by Meddler »

:lol: dang. Now Ive gotta go put my plane on skis and try that. :rolleyes:
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pelmet
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Re: You can't tell snow depth from the air

Post by pelmet »

pelmet wrote: Sat Feb 01, 2014 1:19 am Learned that long ago but was lucky. This guy wasn't.

The Cessna 152, C-GZLF, was on a flight from St. Andrews, MB to Lac du Bonnet, MB. The pilot conducted a low pass before landing to inspect the runway. On touchdown, the aicraft encountered snow up to 12 inches in depth. The aircraft veered left to the edge of the runway, struck a snow drift, and overturned. The pilot and passenger exited without injuries. The aircraft sustained substantial damage to its wings, tail and propeller.
Here is an example of how reading posts in this forum could help prevent an accident....this subject was brought up four years ago as I was hoping it could prevent future crashes. There were some good responses and discussion from other postes and I thank you for that.

Unfortunately, while we will never know if we prevented an accident or two, it appears that these incidents continue. I wonder if it would be beneficial for some of this sort of info to be mandatory teaching for initial pilot training....

C-GQRA, a Cessna 172S aircraft operated by Waterloo-Wellington Flying Club, departed from Kitchener/Waterloo, ON (CYKF) on a round robin night VFR flight to Tobermory, ON (CNR4). Since CNR4 does not have winter maintenance as indicated in the Canada Flight Supplement, there was no intention to land there. However, upon arrival at CNR4, the pilot elected to land. The aircraft touched down on the snow covered runway and flipped over. The pilot was wearing a shoulder harness and was not injured. The aircraft was substantially damaged.
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