Two scrimmage kick situations

[Kalle]

Inspired by the NFHS play situation and maybe entirely trivial

4/10 B-40. A11 punts the ball and the ball is bouncing between B-5 and the goal line heading towards the end zone.

a) A88 stops at B-1, jumps into the air, grasps and controls the ball airborne at B-0.5, and lands in the end zone with the ball having crossed the goal line.
b) A88 runs towards the end zone and while running entirely normally but with both feet in the air (last contact with the ground at B-2) grasps and controls the ball at B-0.5 with his next step landing in the EZ with the ball having crossed the goal line.

Rulings?

[Clarified the situations to reflect that the ball is in the end zone when A88 first contacts ground there in both a) and b)]

[ElvisLives]

As always, it is about the location of the ball related to the plane of the goal line, when it becomes dead.
The ball becomes dead the moment that A88 "possesses" the ball, which means he is holding/controlling the ball firmly with his hands/arms while touching the ground inbounds.
In both examples, if you envision A88 as having grasp/control of the ball in the field of play, but the ball is over/beyond the goal line when he first touches the ground in the end zone, that would clearly put the ball in the end zone, thus, touchback.
In example B, if you envision the possibility of A88 having grasp/control of the ball outside the goal line when a foot first lands on the ground inbounds (field of play or end zone), then, technically, that would be B's ball at the spot of the illegal possession. However, philosophically, anytime there is question regarding the location of the ball in such cases, we are to put the ball in the end zone, and make it a touchback.

[Kalle]

Actually my point was to ask if there is a difference between a striding player and a jumping one, assuming in both cases that the ball is in the end zone when the player next contacts the ground after securing the ball. I tried to clarify the OP.

[ElvisLives]

Actually my point was to ask if there is a difference between a striding player and a jumping one, assuming in both cases that the ball is in the end zone when the player next contacts the ground after securing the ball. I tried to clarify the OP.

The striding BC has to do with forward progress of a BC going OB at a sideline. Since the sideline isn't involved, I don't see any difference between your A and B, in that respect. It is all a matter of where was the ball at the moment it became dead.