Old 14th Apr 2014, 08:41
  #70 (permalink)  
Join Date: Jan 2008
Location: ...
Posts: 3,789
It's because like cyclists they change the lead. But instead of dropping back straight to the back, they dropout to the side (creating the v-formation) and then crossover to the other side. Which means that one of the legs will be longer.
737Jock is offline