Search result sort by distance

Hello,
Apologies for the delayed response.

I don’t recommend set default search results order to something different than relevance, because users don’t expect it.

If you still interested in custom sorting, take a look at this issue – https://stackoverflow.com/questions/10016568/wordpress-custom-field-search-results-sorted-by-value

If your distance is a custom field, it should be helpful.

Best Regards
Damian Góra