Wouldn't the rider be tossed into the water by the sudden deceleration of the sled? I suppose having the sled float makes it easier to haul to shore.Couldn't the people who feel it's necessary to ride on suspect ice wear PFDs? That way they could float while succumbing to hypothermia and divers wouldn't have to risk their lives to retrieve the body.

We have one major problem. How does the sensor, which triggers deployment of the air bag system, differentiate between constantly present melting ice and cold water encountered when the ice breaks? Water pressure sensors are out for obivious reasons and impact monitoring type devices wouldn't work either. I think the best solution might be a self activated unit where the rider would press a button and deploy the bags, though you might end up killing more people who accidentally press the button then you would save in an emergency.

the air bags would also be in the front of the snowmobile and once the snowmobile left a certain atomospheric pressure they would deploy,

[bkeene], I'm not sure what kind of pressure sensor you're talking about. The kind I'm thinking of (which may or may not already exist) would work like a button on a flat plastic panel, like on certain kiosk keyboards. It would need only activate under light, constant pressure (submerged objects experience consistent pressure per surface unit along the portion that is in contact with water).

Now that I think about it, wouldn't the snowboat topple and dislodge the rider? There ought to be a way to factor these events in. All it would need is a way to detect water (differentiating between submersion and mere soaking), and the airbags/float devices would kick in.