It apparently looks chaotic when the flock flies but the group follow more than one leader in the group and then another one. So when on leader changes position, the rest of the flock follow it. It apparently takes about 0.4 seconds to follow the leader's change in direction and there can be more than one leader in the flight. The article doesn't talk about hitting objects.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease