Ours is pretty good.
It is a variation of CISM called Critical Incident Stress Support, is part of a post-incident checklist, which includes, in the first instance, relieving affected staff from duty, ASAP.
Depending on the nature of the incident, this might be immediately (in one I experienced, after sorting out the loss of separation, my voice just shut down. Couldn't speak to save myself. I've seen this in a colleague, in another event, too. Unexpected ) or it might be a few minutes later, when the "dust has cleared"/immediate actions achieved.
It is administered/put in place by management, and the actual support is via ones peers/colleagues, who receive training in what to do. Later, if required, psych support is available. The ATCA is also available for various types of help, including legal, if needed.
Every employee in our outfit has a anti-stress course available. I thought I knew a little about stress till I did the course. It was a major eye-opener. Professionally run, with a number of different speakers representing various associated aspects (Physio, Sleep/fatigue, Personal values system, massage etc) giving us the good goss. Highly recommend.