You can't tell snow depth from the air

[pelmet]

C-FCDM, a privately operated Maule M-7-235C aircraft, was on a flight from Langley Regional, BC (CYNJ) with stops in Hope, Osoyoos and Beaverdell, BC before returning to CYNJ. The pilot had completed two passes over the airstrip at Beaverdell and determined that the snow-covered runway was suitable for landing. Shortly after the touchdown, the main wheels dug into the snow and the aircraft flipped over. The aircraft sustained damage to the wing, wing struts, propeller and windshield. The pilot was uninjured.

[pelmet]

C-FUVJ, a privately operated Bellanca 8GCBC (Scout), equipped with tundra tires, was operating
from Winters Aire Park / Indus, AB (CFY4) to a private airfield 5 nm NNW of Markerville, AB. Prior
to landing on the private airfield, the pilot conducted 2 field surface inspection passes at low
altitude. Due to the field crop stubble being visible through the snow, the pilot determined that the
landing surface snow cover was only a few inches thick. As the pilot attempted to land and the tires
contacted the landing surface, the aircraft sunk into approximately 10 inches of snow. The aircraft
nosed over and came to rest upside down. The pilot, who was the sole occupant, was uninjured
and the 406 ELT was activated. The aircraft received minor damage.
2020-03-21

[pelmet]

While I have driven back and forth along a paved runway with a car to compress a few inches of snow to allow for a reduced takeoff length, I can't say I have heard of what must be deep snow on a grass runway being compressed by heavy equipment for wheel operations. It sounds kind of risky.

C-GWKI, the Academie Aeronautique Inc. Cessna 152 was on a training flight with a student and
instructor on board. During the landing roll at Hawkesbury (CPG5), ON the nosewheel dug into soft
snow and the aircraft flipped over. No injuries were reported but the aircraft was substantially
damaged. The snow had not been plowed from the runway but was compressed by equipment to
provide a hard surface for landing aircraft. Prior to the landing the aircraft flew over the runway to
determine surface condition.

[PilotDAR]

I can't say I have heard of what must be deep snow on a grass runway being compressed by heavy equipment for wheel operations. It sounds kind of risky.

I know an airport which did this years back. Mostly for skiplanes, though some very skilled wheel pilots used the compressed runway. It's a poor idea for wheelplanes. The snow cannot be compressed enough to be helpful, so it ends up being unhelpful, in luring pilots into thinking it might work when it probably won't.

Low pressure tundra tires aside, do not land on snow compressed by anything lighter than the snowplow truck. Snowmobile tracks, for example, are not at all suitable for wheel landings, the snow will not be compressed nearly enough.

If you are not certain that the snow depth is within your's, and the airplane's capabilities, do not land a wheelplane there.

If you land a wheelplane in loose snow, avoid the use of the brakes with great importance! If you use the brakes a little, and the discs warm up, the snow blowing around them will melt and refreeze, locking your wheels solid once you stop. If this is after a taxi in and parking, it's just inconvenient ('cause you're not going anywhere until you melt them). If it happens after takeoff, you have a bigger problem, as you'll be touching down with locked wheels, unless you find somewhere very slippery to land on. When I suspect this was a risk, I'll watch the mainwheel after takeoff, to see it spin down, which is usually a better sign. If I'm in doubt, and I have taken off a slippery runway, I'll go back, and do a touch and go, without touching the brakes at all. If all is normal, I'll continue on. If I feel or see that I have a frozen wheel, I will change my plans accordingly. Carrying a couple of the 50ml white bottles of alcohol for adding to your gas, can be handy for adding to a frozen brake caliper and disc.

[digits_]

Carrying a couple of the 50ml white bottles of alcohol for adding to your gas,

Maybe I'm misunderstanding this sentence, but when would you add alcohol to your fuel?

[PilotDAR]

I should clarify; the little white 50ml bottles are methyl alcohol, which is known to be added to auto gas in cars. It is suitable, and the 50 ml containers convenient for pouring on your frozen brakes to get you going. Isopropyl alcohol is the product to deice airplane gasoline, and should be used as the manufacturer says.

[co-joe]

I've had several high time float guys tell me they hate offstrip ski ops, because you just never know what the snow consistency is until you commit the full weight of your aircraft to it. You can buzz the snow and pack it down several times to get an idea what the density is like but there is a certain amount of pure guesswork to ski ops.

[pelmet]

"C-GMOB, a Piper PA-31-350, operated by Eagle Air Enterprises Ltd. was conducting a VFR flight
from Pukatawagan (CZFG), MB to The Pas/Grace Lake (CJR3), MB with the pilot and 5
passengers on board. The pilot carried out a visual approach and landing on Runway 17 at CJR3.
After the aircraft touched down, the pilot realized the runway was covered in approximately 1.5 feet
of snow. The nose gear subsequently collapsed, the aircraft veered right, and stopped on the edge
of the runway. The pilot and passengers exited the aircraft by the main cabin door. The RCMP and
EMS attended the scene. There were no injuries.

The was no NOTAM runway condition report issued for Runway 17/35 at CJR3; however, the
Canada Flight Supplement advises that Runway 17/35 at CJR3 has no winter maintenance."




Reminds me of the time I went in a Cessna to a not very busy airport that had a fairly long runway. There was no mention in the CFS about No Winter Maintenance and no notam. Runway turned out to be 100% snow covered. I could actually see some runway features through the snow such as different shades of white where crack repairs had been made making me think it was just a centimeter or so of snow. The only portion of the runway that had any disturbed snow was where a vehicle drove onto it for a little bit and then back onto the taxiway. When I did my low flyby, I saw that the car tracks revealed snow deeper than I expected and that it was wet snow as well. Perhaps OK to land but what about taking off and issues with snow on brakes, so I decided not to land. Turned out that there was no winter maintenance that year but no notam.

In the Piper case with no winter maintenance, it would be best to get some local knowledge prior to departure. Somehow, it doesn't seem that surprising that an airport with no winter maintenance in Manitoba has lots of snow on it in mid-January.

[OtherRedBaron]

I can't say I have heard of what must be deep snow on a grass runway being compressed by heavy equipment for wheel operations. It sounds kind of risky.

I know an airport which did this years back. Mostly for skiplanes, though some very skilled wheel pilots used the compressed runway. It's a poor idea for wheelplanes. The snow cannot be compressed enough to be helpful, so it ends up being unhelpful, in luring pilots into thinking it might work when it probably won't.

Low pressure tundra tires aside, do not land on snow compressed by anything lighter than the snowplow truck. Snowmobile tracks, for example, are not at all suitable for wheel landings, the snow will not be compressed nearly enough.

If you are not certain that the snow depth is within your's, and the airplane's capabilities, do not land a wheelplane there.

If you land a wheelplane in loose snow, avoid the use of the brakes with great importance! If you use the brakes a little, and the discs warm up, the snow blowing around them will melt and refreeze, locking your wheels solid once you stop. If this is after a taxi in and parking, it's just inconvenient ('cause you're not going anywhere until you melt them). If it happens after takeoff, you have a bigger problem, as you'll be touching down with locked wheels, unless you find somewhere very slippery to land on. When I suspect this was a risk, I'll watch the mainwheel after takeoff, to see it spin down, which is usually a better sign. If I'm in doubt, and I have taken off a slippery runway, I'll go back, and do a touch and go, without touching the brakes at all. If all is normal, I'll continue on. If I feel or see that I have a frozen wheel, I will change my plans accordingly. Carrying a couple of the 50ml white bottles of alcohol for adding to your gas, can be handy for adding to a frozen brake caliper and disc.

We had a major snowstorm in the GTA recently and I'd recently read this thread. It got me thinking.

I live in a fourplex with six cars parked regularly, behind a pretty long driveway. At the end of this snowstorm there was a 4 foot high snowbank courtesy of the city plows. Our regular plow driver's plow got borked, so we were without snowplowing services for this storm. My car (Subaru, 8" ground clearance with AWD and top of the line winter tires, plus chains if necessary) could make it through, but the remaining, mid-sized sedans, couldn't. Nobody but I could leave the driveway. So I took my car out and used my bumper as a snowplow, driving back and forth over the row at the end of the driveway until most people could get out.

This of course left my car up to its knees in snow. When I took her out the next day, the brakes were frozen solid. It took enough torque that I cringed when the brakes finally broke loose. Now of course, this is in a car, on the ground, at 0kts. I wonder how one would approach this possibility in an airplane - when you fear that snow has melted and then refrozen to your brake calipers/discs.

Touch down on one wheel and see if the plane swerves? Touch down HARD and hope to break any ice loose before bending the prop? Would pumping the brakes and checking for pressure help?

Apologies if this has already been discussed and answered, but my recent frozen car brakes brought it front of mind.

[PilotDAR]

Frozen disc brakes are certainly a risk, I've had it happen a few times.

To prevent, if taxiing in loose snow, do not use the brakes at all, unless it is to lock the wheel immediately, and unlock it immediately. If the disc does not get warm, show freezing on it is a reduced risk - but still possible. After liftoff, do not apply the brakes to stop the wheels (I don't anyway). Let the wheels spin down as long as possible, to cool down without the snow freezing on the disc. Don't fly with wheel fairings in the snow.

If you suspect that you may have a frozen disc, don't land on a hard dry runway, find snow or grass to land on, so a frozen wheel could slide if it had to. If you land on the low friction runway, and one brake is frozen, it's best to maintain directional control, by applying lots of opposing brake if needed. Note that where you land maybe where you're stuck, if you cannot taxi, so try not to block a busy runway. Carry those little white bottles of gasoline deicing alcohol, preferably warm in the cabin. Pouring one of those on the brake caliper will dissolve the ice. Kicking the tire will eventually free it.

In the worst case, you can drop the mains more firmly onto the runway than normal, and hope to break the frozen ice, but this has risks, from losing directional control, to flat spotting a tire. This is best avoided, rather than dealt with after you let it happen.