NTSB Probable Cause

FAILURE OF THE PILOT IN CESSNA 150, N714RS, TO COMPLY WITH THE AIR TRAFFIC CONTROL CLEARANCE, AND FAILURE OF BOTH PILOTS TO MAINTAIN ADEQUATE VISUAL LOOKOUT TO SEE-AND-AVOID EACH OTHER. FACTORS RELATED TO THE ACCIDENT WERE: PHYSICAL IMPAIRMENT OF THE PILOT IN THE CESSNA 172, N128S, DUE TO USE OF DRUGS (CANNABINOIDS), AND FAILURE OF THE TOWER CONTROLLER TO ISSUE A SAFETY ADVISORY.