If you look through the posts from last season, this topic was beat to death. But I'll resurrect it.
7-1-2
The ball is out of bounds when it touches:
a. A player who is out of bounds.
b. Any other person, the floor, or any object on or outside a boundary.
c. The supports or back of the backboard.
d. The ceiling, overhead equipment or supports.
In your play, A1 does not touch the ball when he is OOB and does not have player control. It's a simple as that. If you don't believe me, here are two similiar sace book plays.
7.1.1B.
A1 blocks a pass near the end line. The ball falls to the floor inbounds, but A1, who is off balance, steps off the court. A1 returns inbounds, secures control of the ball and dribbles.
Ruling: Legal. A1 did not leave the court voluntarily and did not have control of the ball when he/she did. This situation is similar to one in which A1 makes a try from under the basket and momentum carries A1 off the court. If the try is unsuccessful, A1 may come back onto the court and regain control since A1 did not leave the court voluntarily and did not have control of the ball when he/she did.
7.1.1C
A1 blocks a pass near the sideline and the ball goes into A1's front court. A1's momentum carries him/her out of bounds. He/she immediately returns inbounds, secures control of the ball, dribbles, shoots, and scores.
Ruling: Legal. (4-35-1A; 7-1-2; 9-3)