What happened
The pilot departed from North Perry Airport, intending to fly toward Opa Locka Airport to collect the first banner of the day. Although the pilot noted thunderstorms in the area, banner operations were continuing. After two coworkers had already completed their pickups, the pilot approached the poles for his turn, deploying the hook and flying the pattern.
Upon approaching the poles, the pilot applied full engine power and successfully picked up the rope. As the ground crew signaled that the banner was about to be lifted, the pilot lowered the nose of the Cessna (type not specified in source) while at an altitude of approximately 175 feet above the ground. Instead of leveling off as expected, the aircraft began to sink. As the banner was picked up, the sink rate accelerated rapidly. The pilot maintained all engine levers in the full power position for approximately two seconds, but the sink rate did not normalize. Realizing a hard landing was imminent, the pilot released the banner and landed straight ahead.
Findings
The aircraft experienced an unexpected increase in sink rate during the banner pickup process, which accelerated immediately after the banner was secured.