Backcourt violation?

[Wing4444]

A1 has secured the ball in its own froncourt.A1 then throws the ball to A2 who started in the backcourt jumps in mid air and lands with both feet in the frontcourt the ball never breaks the plain of the division line and at no time did A2 possess the ball in his backcourt or touch it there.
I saw this called a backcourt violation in a game last week. I am a rookie official but there is no were in the rule book were I can find this an exception to the rule please help.