Final answer:
To control heavy bleeding in a tactical field care situation, apply direct pressure to the wound and use a tourniquet if necessary.
Step-by-step explanation:
When encountering a casualty with heavy bleeding, there are several steps you can take to provide immediate care. First, apply direct pressure to the wound using a clean cloth or your hand. Maintain pressure until the bleeding stops or medical help arrives. If the bleeding does not stop, you can apply a tourniquet above the wound to restrict blood flow. However, make sure to release the tourniquet every 15-20 minutes to prevent damage to the tissues.