I assume they are going at slightly different speeds, but one thing got me thinking.
What if the plane the photo is taken from "falls out of the sky" (sorry, don't know the proper english terminology) ?? Remember the JAL DC-10 that fell a couple of thousand feet due to clear air turbulence (?) Wouldn't that be a potential safety risk in congested airspace? If that happens to this A/C (or both), they would sure get uncomfortably close to each other!
Any airline pilots or passengers with experience from such an event?
Altitude is Insurance - Get Insured