Animating a Locator on a Path in Maya

"If you want to animate the camera on a path coming down while looking at the spaceship and the hangar bay entry door, the first thing you need to do is create a locator object. This object will be animated along the path the same way the spaceship has been animated along its path" 

Reference:
(http://www.cadlearning.com/maya/animating-a-locator-on-a-path/)  

Step By Step: