A blimp is steady in place high in the sky, tethered by 3
cables
in a pyramid shape.
There are two more blimps, one at each of two
"stations".
A rope from the main blimp serves as the swing.
A quadcopter at the bottom of the swing brings the
rope to its
initial position at one of
the stations.
The packages or passengers are elevated by a motor
on the
ground and a pully on the station's blimp. The package
is
hitched on to the swing. Lets go of the station's cable
and woo
hoo! Off to the next station where it is caught, and
slowly
brought down to earth, or hitches onto the next swing.
See link about Ruwandan plane that hitches onto a
catching cable.