Would like to hear some feedback from everyone on why or why not you land on frozen rivers. I have heard some people say there is absolutely no way they would land on rivers and others, including myself, that land on them all the time. I know alot has to do with comfort level, and just personal preference and in no way am I trying to encourage anyone to land on rivers. Mainly trying to get peoples experience and expertise on the subject. Thanks in advance.

Absolutely perfect timing MH! I was just getting ready to post about an event I had yesterday, when I saw your post, so I'll make my post on your thread. Here's one reason, though this was not a river but a (river fed) reservoir, but what really got my attention was that where this happened, there was no obvious signs of any inflow of water to make one suspect a less solid surface. I had been leaving tracks for a 1/4 mile or so, no reason, just because I can....and was idly thinking maybe I'd come to a full stop and get rid of some coffee, when I felt a change in the surface and actually heard the ice break. I lifted off and went around, this pic was less then a minute later, I found it real interesting. 8 degrees OAT. This res is quite large, and I never did see anything that made this area suspect, (other then it was a bit close to the shoreline, but that shoreline looked innocent) even looking especially hard, after the event. I was going just a hair below flight speed, but at a good water skiing speed, so I don't feel I almost got wet, but it did make me wait until another res a few miles away, with ice fisherpersons and sled tracks all around, to come to a full stop.

I can see a river landing proper being even more "dynamic", as in who the heck knows. Snowmobiles are the ski pilots friend I have found, and ice fisher types, but watch out for their frozen chip piles their augers leave. I spent a lot of time in Michigan as a kid on frozen lakes, my family was into ice boats, this occurrence really got my attention, yeah I know the term for it is "overflow", but why there?

In the first pic above note what appears to be a crack in the ice to the left of the tracks. Follow that line to the wet spot. Ice does that via expansion as it forms and often that crack can also form parallel to the lake or reservoir's edge as the water draws down during winter. Water below under pressure from the ice and snow weight above will seep up to eventually establish a new frozen level at the surface. When the snow melts the overflow ice is indicated by being opaque (a mixture of snow and water) unlike the clear ice below.

As far as river ice in Interior Alaska here's a good reference to review:

http://chasjones.com/wp-content/uploads ... -River.pdf

Hi Steve, your Citabria looks good.

Gary

More so than lakes, the rivers near me are apt to have driftwood logs and root balls and gravel berms and such under the snow. I still land them as needed, but my level of alertness is heightened accordingly. The other thing that can happen on the larger, often braided rivers here is that a submerged sand bar will cause the ice above to be thin. Then the currents can change, removing the sand bar and leaving a dangerous thin spot. These are effectively impossible to read from above. On a kind-of related note, I have heard that last month’s 7.0 earthquake near Anchorage seems to have opened up some new warm springs on lakes including Big Lake and Mud Lake, resulting in new, uncharted weak spots. If anyone has more info on this please consider sharing it. Thanks.

There are lots of ways to get in trouble on rivers. Of course, there are "rivers" and RIVERS. And they behave and freeze up very differently. Local conditions can be quite different even on what appear to be similar streams.

A commercial air taxi operator out of Fort Yukon supplied a family that lived upstream on the Porcupine River. He flew a 185 on retractable wheel skis. He flew in there at least once a month, but usually more frequently.

His "landing strip" was right in front of the cabins, on an outside bend of this fairly fast river. I landed there a few times, and it was nicely prepped for skis.

One year, late in the winter, he landed there, and about midway down the strip, the plane fell through the ice, right up to its wings. Pilot got out okay, but this was strange, since temperatures were regularly well below zero F. There had been no thaws at all.

Eventually, the theory offered was that this fast river had actually eroded the ice out from under the compacted snow at that bend in the river. When they dug around there, there simply was no ice where the plane had fallen through, or very little. It's possible that the snow over the fall new ice prevented the ice from getting thicker, but the prevailing theory was that the ice was eroded from below by the fast, strong current at this outside bend.

I stayed away from outside bends after that....

MTV

Mike has a good point about ice erosion under outside bends via underwater current. The inside of the bend is generally less prone to erosion, is composed of older ice, and over shallower water should the plane break through. But there debris like logs and rocks can be present as the water level declines during winter. Pay attention to where local snow machines travel if possible.

Another caution is taxiing too much or too fast (>15 mph) over thin ice. The weight of the plane can slightly compress the ice and create a pressure wave around the plane. Wiki and others recommend a maximum speed to travel and blah blah. Of course the thicker the ice or lighter the vehicle the less the chance of it happening. It's a fact that an approaching snow machine will make the water level in an ice fishing hole move up and down. Not sure what the fish below think of all that.

https://en.wikipedia.org/wiki/Ice_road#Driving
https://physics.stackexchange.com/quest ... n-ice-road

No easy answer. Unless there's a good reason to land and you're uncertain why bother?

Gary

Very good info. Thanks guys. I have some very remote property on the Kuskokwim River that requires me to land on unknown river conditions quite a bit. I stay clear of the main channel and use areas that i know the water is slower. I have made 10 or more passes dragging the snow before committing to a landing several times. I also use moose tracks as a good indicator that the area is stable enough to land on. Still scares the hell out of me every time though.
Thanks for the compliment Gary. I'm parked over at Chena Marina if you ever want to grab coffee.

Good post Moosehunter,
All rivers are tricky, and of course the only real way to be sure is have someone check it from the ground ......... Of course that is not always possible in Alaska! Dragging for overflow is always a good idea. But no doubt if a guy keeps at it long enough landing on moving water he will eventually get wet! Lol
Good luck on the Kusko, I have landed all over it and never went thru but lots of others were NOT as lucky......... I will personally land on snowmachine tracks alot hoping the guy that laid em down knows the river alot better than I do. We have 26" of ice here on the lakes in Northern Maine. I landed on the Mattawemkeg
River on Sunday and it was -15 below zero. Just for fun I screwed my ice chiesel togeather and in 10/12 whacks I was thru!! Only 6/7" on the river.......
Fly safe
E

Recent trip to a buddies cabin. Iditarod checkpoint at Eagle Island, Yukon River. Getting machines ready to build a couple of strips for the Iditarod Airforce. First frozen river landing on the Yukon.

Steve's hunched over a SkiDoo I likely gave to him a few years ago. If that's the same one it ran good for me. Hope he has a good time, but I know in some ways it's tough for him to return to the family home and pay respects to his parents. He had a life when young few will ever experience. He put the sled on his floats and flew it to town. Said he never knew it was even there.

Gary