I was going to go aboard on my spaceship. Everything worked, but once I got down the stairs and I was about to go into the fence gates. I phased through a glass block and I ended up falling out of the space ship.

What I expected to happen was...:

I expect to be able to move around the spaceship without phasing through it.

What actually happened was...:
Sometimes when I move around in the spaceship my minecraft character phases through the glass or the spruce wood, and I end up falling off the spaceship.

Steps to Reproduce:
1. Make a piston spaceship.
2. Start up the engine and run towards the stairs outside the passenger seat.
3. Once you're on these stairs / inside the spaceship. When you're not sitting in the minecart, you risk yourself to fall out of the space ship.

I think the problem lies within the movement of the piston. If a minecraft character moves into a constant moving piston, it is possible to phase through it.