Not something you're likely to see on the approaches to LAX, Heathrow, Schiphol or Changi, but in years to come aircraft may fly in formation at altitude.
One part of the wide-ranging Aero 2075 report by the Institution of Mechanical Engineers in the UK, looking a the future of aviation, proposes aircraft fly in a V-shaped formation to allow some in the pattern to experience less drag and improve lift.
"Taken directly from nature", the report says, "the concept is akin to the aerodynamic nature of a flock of geese."

"The aircraft could join the flight mass through mechanical docking to form a semi-rigid body of several aircraft. The automated docking would allow aircraft to join the flock in a computer determined best flock position which it would approach on automatic control and then latch to the flock.
"Aircraft leaving the flock would need to have pre-programmed their sequence of departure so that they were not locked into the centre of the flock when they needed to leave."
Here is a clip:
NB:Part 1 and Part 2 of the report are available to download, covering economics and challenges of the aviation industry as well as detailed studies into future aircraft design.