Create a Loading page between two PHP pages

[Kurt]

I have two PHP pages...page A and page B. Page A is basically a form that takes input values from a user and posts them to page B which runs a python script to do some calculations over the submitted values and presents the calculated values on page B. I want to include a page C in between A and B which displays a loading bar or icon meanwhile the page B's content is prepared to be displayed, and then directs user to the page B. Is there a pure PHP or PHP+JS+CSS way of doing this?The idea is to capture the status of page B and the user is only directed to Page B from Page C when Page B's content is ready to be displayed.