FYI, https://www.washingtonpost.com/news/post-nation/wp/2017/03/15/a-man-claimed-he-stood-his-ground-with-a-warning-shot-a-judge-revoked-his-carry-permit/?hl=1&noRedirect=1&utm_term=.6aea42e2c999
Warning shots went out with Joe Friday and Dan Matthews. A bullet has to stop somewhere, and firing into the ground doesn't guarantee that it's going to stop there.
A tough situation, as I read the article. He saw what he believed was someone being beaten-up by 2 other guys, and tried to intervene with supposedly good intentions. The warning shot was where he went wrong; whether or not that's deserving of getting his permit revoked, that's the question.