This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
I was scheduled to fly over an event on the coast in my Stearman. I arrived about 20 minutes early and began orbiting nearby.
The visibility was excellent and the air was smooth. I could see the mountains in the distance and the pier about eight miles to the southeast.
Rather than continuing to orbit, I decided to fly along the coast past the pier and back. I visually cleared the route from my location to the pier and turned on course, level at 1,200 feet msl. I began a shallow descent off shore.
As I descended through about 800 feet, suddenly there appeared a banner tow aircraft just barely above and slightly to the left. I pushed down and to the right, narrowly avoiding a midair collision.
After the event, I realized that I had made a mistake. Even though I had visually cleared the area in front of me, I should not have flown a shallow, wings level, straight-ahead descent. I should have made one (or more) S-turns during the descent to scan for traffic ahead and below my flight path.
Primary Problem: Human Factors