Today's ice flying...

http://i381.photobucket.com/albums/o...R/IMG_2185.jpg

By the bouy....

http://i381.photobucket.com/albums/o...R/IMG_2187.jpg

You can see the lake bottom throught the ice, though it is now 9 inches thick....

C 150 Ice takeoff video by PilotDAR - Photobucket

Video clip of takeoff from the ice...

Chapter and verse are available from the book: Seaplane Operations by Dale de Remer chapter 16 section 8. Original formula from RG Weber, later studied by a russian called Moskatov.

I'd would be inclined to build in a fudge factor into it, there seems to be alot more to it than just the theory.

Irish

Back in the 70s, I jump-seated in a 748 (CF-CSE) that landed on an ice runway by a drilling rig in the Mackenzie Delta. This was a regular operation throughout the winter. I don't know if they used ice-road techniques to thicken the ice.

I have flown onto ice in both Beaver and Otter on skis with our local floatplane operator. He says rule of thumb is 6" plus 1" per thousand pounds.

Good rule, though I'm not sure the math still works for Twentygrand's Starlifter landing!

We have a fly-in on the ice of Lake Nummijarvi, near Kauhajoki, Finland on March 11 & 12. For the 9th year now, in fact. Dozens of aircraft taking part. The largest is an Antonov 2. Great fun. Lots of pictures from last year here:

Nummijärvi Fly In 2010

Some video clips of fun on the ice...

(I'm not quite sure how to make Photobucket do this, but there are videos there somewhere...)

http://i381.photobucket.com/albums/o...h_MVI_2219.jpg

http://i381.photobucket.com/albums/o...h_MVI_2213.jpg

http://i381.photobucket.com/albums/o...h_MVI_2210.jpg

http://i381.photobucket.com/albums/o...h_MVI_2207.jpg

http://i381.photobucket.com/albums/o...MVI_2206-1.jpg

In the US, a seasonal ice runway has been operated for many years (with FAA approval) at Alton Bay in New Hampshire. I understand they look for 12 to 14 inches of ice to open but that's more to support the plow trucks than the aircraft. When I was flying on skis with a 7ECA we use to look for cars/trucks driving on the ice or more than 6". Comments above are correct, local conditions and knowledge matter more that a single minimum number of inches.

AOPA Online: Alton Bay ice runway opens