Spot probing involves probing high-probability areas. It is used when the victim doesn't have an avalanche transceiver or when the transceiver has stopped transmitting.
High-probability areas include near clues (e.g., skis or a snowmobile), uphill of catchments areas (e.g., trees, bushes, rocks), in depressions, near the toe of the avalanche, downhill of the point last seen, etc.
During spot probing, it is advisable to not probe deeper than 1.5 meters (5 feet) . Surviving a such a deep burial is extremely unlikely; it is a better use of your time to search more locations.
You can hold your probe at any angle when spot probing (when probing after a transceiver search, the probe should be held at 90-degrees relative to the snow surface).