I am putting myself in their shoes. I wonder if they were scanning really trying to acquire the aircraft and lost concentration on altitude. I was a hawk driver in a previous life and it takes just a smidge of back pressure on the cyclic to get a pretty good climb going. Further, maintaining 200 feet would require whoever is on the controls to be looking inside on the instrument panel quite a bit. Focusing outside for an extended amount of time would definitely cause the altitude to drift, and 100-200 feet is nothing.

You know, this has made me think at all of the times I made a mistake or got away with something while flying. Anyone who has flown for more than a day knows that all of us have had our share or screw ups, some small and some big. The more I look back the more I realize that at times it was dumb luck that kept me alive. So tragic for all involved.