Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 26; Flight Crew Total 5597; Flight Crew Type 2593
Distraction; Situational Awareness
Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
Human Factors; Procedure
I was scheduled to fly over an event on the coast of ZZZ. 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 8 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.
Pilot reported a near mid air collision and took evasive action.