automatically open .ics in outlook

I have OS X ElC Vers 10.11.6 with outlook vers 15.23

I would like to add calender events showing in web pages using Safari 9.1.3 (this events are travel schedules, meetings, etc.). Safari downloads the .ics file into the downloads folder, then the OS starts the calender app (vers 8.0) for opening the .ics file. However, I would like to see it opening in outlook automatically (and there are several reasons for that).

What I tried so far go to the downloads folder, click on "open with ...", click, "other program", choose the outlook app, check the "always open with" checkbox. And the.ics files opens with outlook. However, the next time the system has forgotten about and the behavior as described happens again. I see the default .ics app is the calenderfilehandler.app, is there a way to configure this. Or is the problem in the OS not remembering to open a file with a certain application?