Ditto what Jerry said. Avy beacons would be a very poor choice for the situation described. For some actual test results of the range of some popular beacons see http://beaconreviews.com/transceivers/RangeTestResults.asp

This shows most have a maximum range of about 30-80 meters, under ideal circumstances. The digital beacons, which are most populur now becasue they indicate both direction and distance, are mostly less than 50 meters. For about the same price of an avalanche beacon, one could buy a proper PLB. A SPOT could be obtained for less.