MUST SEE, VERY CLOSE: A340 meets B777 at 33.000ft over the Yellow Sea!!! [AirClips]

The Boeing 777 is a family of long-range wide-body twin-engine jet airliners developed and manufactured by Boeing Commercial Airplanes. It is the world's largest twinjet and has a typical seating capacity of 314 to 396 passengers, with a range of 5,240 to 8,555 nautical miles (9,704 to 15,844 km). Commonly referred to as the "Triple Seven", its distinguishing features include the largest-diameter turbofan engines of any aircraft, six wheels on each main landing gear, fully circular fuselage cross-section, and a blade-shaped tail cone. Developed in consultation with eight major airlines, the 777 was designed to replace older wide-body airliners and bridge the capacity difference between Boeing's 767 and 747. As Boeing's first fly-by-wire airliner, it has computer-mediated controls. It was also the first commercial aircraft to be designed entirely with computer-aided design.
The 777 is produced in two fuselage lengths as of 2017. The original 777-200 variant entered commercial service in 1995, followed by the extended-range 777-200ER in 1997. The stretched 777-300, which is 33.25 ft (10.1 m) longer, followed in 1998. The initial 777-200, -200ER and -300 versions are equipped with General Electric GE90, Pratt & Whitney PW4000, or Rolls-Royce Trent 800 engines. The extended-range 777-300ER and ultra long-range 777-200LR variants entered service in 2004 and 2006 respectively, while the 777F, a freighter version, debuted in February 2009; these variants all feature high-output GE90 engines and extended raked wingtips. The 777-200LR is the world's longest-range airliner, able to fly more than halfway around the globe, and holds the record for the longest distance flown non-stop by a commercial aircraft.

Designed to replace early-generation Boeing 747 airliners, the A340-600 is capable of carrying 379 passengers in a three-class cabin layout 13,900 km (7,500 nmi). It provides similar passenger capacity to a 747 but with 25 percent more cargo volume, and at lower trip and seat costs. First flight of the A340-600 was made on 23 April 2001. Virgin Atlantic began commercial services in August 2002. The variant's main competitor is the 777-300ER. The A340-600 will eventually be replaced by the A350-1000.
The A340-600 is 12 m (39 ft 4.4 in) longer than a -300, more than 4 m (13 ft 1.5 in) longer than the Boeing 747-400 and 2.3 m (7 ft 6.6 in) longer than the A380. It held the record as the world's longest commercial aircraft until February 2010 with the first flight of the Boeing 747-8. The A340-600 is powered by four 250 kN (56,000 lbf) thrust Rolls-Royce Trent 556 turbofans and uses the Honeywell 331–600 APU. As with the -500, it has a four-wheel undercarriage bogie on the fuselage centre-line to cope with the increased MTOW along with the enlarged wing and rear empennage. Upper deck main cabin space can be optionally increased by locating facilities such as crew rest areas, galleys, and lavatories upon the aircraft's lower deck. In early 2007, Airbus reportedly advised carriers to reduce cargo in the forward section by 5.0 t (11,000 lb) to compensate for overweight first and business class sections; the additional weight caused the aircraft's centre of gravity to move forward thus reducing cruise efficiency. Affected airlines considered filing compensation claims with Airbus.
The A340-600HGW (High Gross Weight) version first flew on 18 November 2005 and was certified on 14 April 2006.[110] It has an MTOW of 380 t (840,000 lb) and a range of up to 14,630 km (7,900 nmi), made possible by strengthened structure, increased fuel capacity, more powerful engines and new manufacturing techniques like laser beam welding. The A340-600HGW is powered by four 61,900 lbf (275 kN) thrust Rolls-Royce Trent 560 turbofans. Emirates became the launch customer for the -600HGW when it ordered 18 at the 2003 Paris Air Show; but postponed its order indefinitely and later cancelled. Rival Qatar Airways, which placed its order at the same airshow, took delivery of only four aircraft with the first aircraft on 11 September 2006. The airline has since let its purchase options expire in favour of orders for the Boeing 777-300ER.
In July 2015, seven airlines worldwide operated A340-600s. In April 2016, there were 77 A340-600s in service.

Although this may appear very close, please note that there is more than enough vertical separation for this maneuver. This is common practice and happens every minute up in the skies, even with much less vertical separation. This example just nicely shows the use made out of airways.