that doesn't appear to me to be the same thing as the multiple planes doing the crisscross patterns. this thread is long and i haven't read it all, but has anyone explained the difference between one plane with a con? chem? trail behind it as opposed to 2 and sometimes 3 crisscrossing over the same area for hours?
...2 and sometimes 3 crisscrossing over the same area for hours?
how do you know they're the same 2 or 3 planes?
the fact that you repeatedly get contrials over the same spot is explained by the fact that a ground-based navigation aid that determines the route of a federal airway is located beneath the planes' flight path.
parallel contrails are often indication of a crosswind: a plane flies over a navaid at X time of day in a 40 mph crosswind...
...then, at X + 15 minutes, another plane flies over the same navaid, and in the meantime, the contrail from the original plane has moved downwind 10 miles.