Talk:World 1/@comment-24930367-20151024162957/@comment-26460664-20151025090424

It could be RNG, or some logical reasons:

1. Accident happens as mentioned by 139.216.148.160.

2. In WW2, submarines are equipped with AA guns to fight against planes. However, they can only take down a few of your planes because it has limited guns. (see also: http://www.fleetsubmarine.com/guns.html)