Pilots of a Boeing 777 have captured an incredible video of Boeing 747 overtaking a Boeing 737. The Boeing 777 was at 33,000ft, while the 747 was at 35,000ft and the Boeing 737 at 37,000ft. SEE Striking pictures and video of BOAC 747 in formation with the Red Arrows. Aircraft flying in the same direction are separated by 2000ft while aircraft flying in the opposite direction, the same separation, but at even altitudes, thus aircraft flying in the opposite direction to each other are just 1000ft apart. https://twitter.com/i/status/1153073076453724161 Separations of just 1000ft are standard today for suitably equipped jets with the sophistication of autopilots and cockpit automation as well as satellites. Suitability equipped jets are described as Reduced Vertical Separation Minima (RVSM). Within RVSM airspace (between FL290 and FL410 inclusive) the vertical separation minimum is:

• 1000ft (300m) between RVSM-approved aircraft, and
• 2000ft (600m) between non-RVSM approved state aircraft and any other aircraft operating within RVSM airspace.
• 2000ft (600m) between non-RVSM aircraft operating as general air traffic (GAT) and any other aircraft within RVSM airspace.