Piper PA18 N796AB accident near Bay City, Michigan

Probable cause

The pilot's failure to maintain airspeed and his exceedance of the airplane's critical angle of attack during a banner drop and pickup, which resulted in an aerodynamic stall and a subsequent loss of control.

NTSB analysis

The commercial pilot had completed one banner tow flight and was dropping the banner and picking up a second banner when the accident occurred. The operator reported that the pilot could not recall the events of the accident; however, witnesses saw the pilot conduct the banner drop from about 250 ft above ground level. After dropping the banner at an idle or nearly idle engine power setting, the airplane pitched up and abruptly banked left, impacting the ground about 180° from its previous heading.

The operator suggested that the pilot's attention may have been diverted following the drop, and while operating at a low engine power setting, the airplane slowed and experienced an aerodynamic stall. The operator reported no preimpact mechanical malfunctions or failures with the airframe, engine, banner, or the tow equipment that would have precluded normal operation.

It is likely that the pilot failed to maintain adequate airspeed during the banner drop and pick-up procedure and exceeded the airplane's critical angle of attack. This resulted in an aerodynamic stall and subsequent loss of control at an altitude that precluded recovery.

Text from the NTSB. Open the NTSB docket for CEN19LA214 for the full record.