PacketPlayInFlying sent only once

Hello, i have packet reader in my plugin but when i listen for PacketPlayInFlying, it execute only once when i join the server, later not.. any idea?

Code:

public void readPacket(Packet<?> packet){
if(packet.getClass().getSimpleName().equalsIgnoreCase("PacketPlayInFlying")){
Bukkit.broadcastMessage("flying");
    }
}

this broadcasts "flying" only once