Runway incursion of the worst kind

Back in the early 1970s, before runway incursions were a notable and common problem, I experienced my worst close call. After returning home from military service, I applied for the GI Bill, and I obtained my airplane flight instructor certificate. I returned to the flight school where I had learned to fly and received a job flying Piper Colts. Shortly thereafter I moved up to the modern and nimble, all-metal Cessna 150 and was much happier in that airplane. Had I been flying a Colt when this incident took place, I don't believe my student and I would be alive today.
http://www.aopa.org/pilot/never_again/2005/na0504.html