1.
If you ~ a person, animal, or vehicle, you move to a place in front of them in order to capture them or make them change the direction they are moving in.
He changed direction swiftly, turned into the hallway and headed her off.
PHRASAL VERB: V n P, also V P n (not pron)
2.
If you head something off, especially something unpleasant, you take action before it is expected to happen in order to prevent it from happening.
He would ask Congress to intervene and ~ a strike...
You have to be good at spotting trouble on the way and heading it off.
PHRASAL VERB: V P n (not pron), V n P