While Hulk could argue come close to Superman in terms of strength, physical muscle exertion, when Superman is flying he is defying Gravity, so there is no limit to his propulsion ability
In the first Superman film, Jor El tells him he can propel himself at "almost limitless speeds"
In Superman Returns we see him lift a continent - this is possible because the continent weighs nothing when there is no gravity
Despite Hulk's strength, Superman has his speed, as fast as Flash or Whizzer, faster than Hulk could see, his heat vision, and his flight
Perhaps the only Marvel hero who could match Superman would be Thor
So yes, flying Hulk to the upper stratosphere, or whatever it should be called. where he can't breath - and where there is extreme cold of course
Hulk has awesome strength, but no match for Superman
