Q:

Open Outlook calendar form

Is it possible to open Outlook meeting form when an event on SharePoint calendar is clicked (or double clicked)? 
Using ics export is not an option.

A:

The outlook meeting form is in a client application.
The SharePoint calendar is in the web browser.
There is no way to trigger the client form from the browser easily.
If you still need to do this, you will probably need to:
1) write some sort of script to launch the outlook form (vbs)
2) install a protocol handler (eg outlook://) to execute the script
3) customize the calendar to call outlook://
And that might not even work

