[Ref in PA]

Just about every blocking foul is by a player getting to a spot before the other player, but not being legally entitled to that spot. If A1 and B1 are on intersecting paths, establishment of the point of intersection is critical to making the correct call either the block or the charge. In the play situation, B1, the defensive player has chosen a path and established it (jumping in the air to a new spot). At the time of the jump of B1, there was no collision course between A1 and B1. While B1 is in the air, A1 chooses a path that causes a collision. What you have is a blocking foul on A1 even though A1 has the ball! If the ball possession were reversed and B1 jumps first with the ball and A1 cuts under him after the jump - everyone of you would call a blocking foul. Legal guarding position has nothing to do with this play.

4-7-1 "Blocking is illegal personal contact which impedes the progress of an opponent with or without the ball."

A1 chose to impede the progress of B1. The fact A1 has the ball should not matter.

If A1 and B1 were committed to intersecting paths, then an airborn leap by B1 would not save him from a foul if A1 were to get to the spot of intersection first. The big difference in my opinion is A1 choosing a new path to cause the contact.

I am with JR and Kevin on this one.