Can plane climb without increase pitch angle?
Basically a plane will climb, descend or maintain altitude depending on two things: the angle of attack of the wing, and airspeed.
So, yes, it is possible to trasition from level flight to climb just by increasing speed, because as the speed increases, there is more airflow around the wing, and it will create more lift.
Also, generally planes have a natural tendency to pitch up if speed is increased and nothing else is done, further adding to the climb speed. Aeroplanes tend to &quot;try&quot; and maintain the speed they are trimmed to, hence the upward pitch as the plane is seeking to shed the excess airspeed by transitioning the extra energy into altitude gain.