I would recommend the Spyderco Delica 4 folding knife. If you prefer a Swiss Army knife, I would go with the One-handed Trekker which has a blade, a saw, and screwdrivers (those always come in handy when you work with ATVs and other pieces of machinery).

I feel a fixed-blade might add too much weight and be cumbersome in SAR operations. Honestly, any knife that will cut through thick rope and clothes is fine (which is why I recommended the Spyderco Delica in the first place).