Only the most desperate, geometrically-challenged journalist could describe that as "near-vertical".
Actually, somewhat of an explanation.
As the Vietnam Airlines crew kept close tabs on the climb rate, airliner vehicle speed, and "glass cockpit" command bars, the near "S-vertical" takeoff momentarily shifts the Boeing 787-9 in an aggressive flight takeoff performance mode akin to a rocket propulsive system.
Fluidic momentum suggests the near vertical thrust needed to achieve the rapid climb equals a large air intake mass flow through the engines multiplied by an even larger engines' exhaust jet velocity, due to the high vehicle speed of the Boeing 787-9 vertically upward, as seen on the company video.
According to Boeing, the following facts are the conditions for the Boeing 787-9 Dreamliner's near vertical takeoff using either General Electric GEnx-1B or Rolls-Royce Trent 1000 engines: Bypass ratio = 10; Fan diameter = 111-112 inches; Overall pressure ratio = 50; Thrust = 53,000-74,000 pound-feet;
Hence, the near vertical thrust readings on the "glass cockpit" command bar of the Boeing 787-9 airliner is essentially a non-dimensional ratio of two characteristic velocities — one, which is an exhaust jet dependent on how well the engine flow stream is designed, over another, which is a characteristic velocity about 40 percent higher than the speed of sound inside the combustion chambers of the engines.
However, we can also define another figure of merit, called the specific impulse, as directly related to the overall efficiency of the engines of the Boeing 787-9 Dreamliner in performing the near "S-vertical" takeoff. The specific impulse in performing this takeoff is a ratio of the near vertical thrust divided by the temporal rate of change of the Boeing 787-9 weight.
The overall (propulsion system) efficiency may be approximated as a product of the propulsive efficiency and the thermal efficiency. (Note: an engine's overall efficiency measures a ratio of the engine's thrust power (or "useful propulsive work") to available fuel burn energy).
When we take the Boeing 787-9 near vertical takeoff speed, Uo, multiplied by the specific impulse, Isp, we get a measure of the engines' thrust power. The available fuel burn energy is a ratio of the heating value of the fuel, H, to the gravitational constant, g.
Thus, the overall efficiency, Neff, of the Boeing 787-9 Dreamliner, performing as a near vertical takeoff rocket propulsive system, is Neff = (Uo)(Isp) / (H/g).
In summary, these seven (7) performance figures of merit — (1) fuel burn energy, (H/g), (2) specific fuel consumption (SFC) (which measures engine fuel burn efficiency), (3) specific impulse, Isp, (4) engine thermal efficiency, (5) overall (propulsion system) efficiency, Neff, (which is highly dependent upon the closely-monitored airliner's takeoff flight speed and near vertical flight speed, Uo), (6) engine thrust power, (Uo)(Isp), and (7) nitrogen oxide (NOx) emissions (for aero-environmental propulsion engineering design considerations) — are altogether central to the Boeing 787-9 aviation achievements exhibited at the 2015 Paris Air Show on June 15-21, 2015 at Le Bourget Exhibition Centre outside of Paris.
Not a trick, on the ground looked closer to 80 degrees than 30 degrees..everyone around thought something had gone wrong...
Its a simple thrust to weight ratio balance, taking took some queues from the technique of tail walking a fighter jet.
Sorry to disappoint, but really, I did see this aircraft at the airshow, and the initial climb with the nose rolling over was about straight up at that point. The report references screen shots on the glass cockpit from the manoeuvre from Boeing website (these are no longer available)
Bloggs, the 21 degrees that you show was after the roll, and really, 20 degrees is normal, so that is typical.
and the A400 roll? Camera tricks?
https://www.youtube.com/watch?v=fRtOGJTqjkQ