Playtime issue with animations My goal is to have the animation I have set up play which is triggered by a collision with the players body to a sensor, in which the body gets deleted, the camera and gun switch parents to a helicopter, and then play their 1300 frame actions.

When I do this, the gun and camera return to the origin yet still play their respective actions alongside some relative changes due to distance from parent. I do not understand how to fix this and make the animation look as it does in the preview/timeline view.

I have attached the file from my game with all the relevant information, if you can get this animation to play correctly and identify the problem I would greatly appreciate it, been stuck on this for a while now.

https://www.dropbox.com/s/xskpc8arpj37roy/fixcut.blend?dl=0
This sounds like the child objects have impact on the physics.
I assume your helicopter is rigid-body. That means it can collide with other objects such as static objects.
Now you parent the character object to the helicopter. I guess the character object is still static (or was dynamic and becomes static via parenting).
The problem is that the character object collides with the helicopter. The helicopter (as rigid body) will change position due to the impact. As the character object is parented to the helicopter the collision will always be present, making the helicopter move even further.
Solution
Ensure there is no collision between parent and child.
This can be by making the child ghost or by ensuring there is no intersecting face between the different physics meshes.