On November 20, 2022, about 1149 central standard time, a Piper PA-28-140 airplane, N267PC, sustained substantial damage when it was involved in an accident near Saint Joseph, Missouri. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he recalled communicating with ATC for his taxi clearance to runway 17. The pilot did not recall any events after acknowledging the taxi clearance. An ATC controller issued taxi instructions to the pilot for a visual flight rules departure and observed the airplane taxi to the run-up area near runway 17. After completing the run-up, the pilot was instructed to contact the ATC tower. After no communications were received from the pilot, the controller attempted to initiate contact but there was no reply. Several attempts to contact the pilot via radio were unsuccessful and the tower controller noticed the airplane had turned around in the run-up area. Based on the airplane’s repositioning, the controller assumed the pilot was looking for a light signal and issued a green light. When the airplane did not move, the controller made several more attempts to contact the pilot but there was no response. The controller then noticed that the airplane appeared to be taxiing back to the general aviation ramp; however, the airplane accelerated, departed the movement area into the grass and impacted a perimeter fence. Postaccident examination of the airplane revealed no evidence of any preimpact mechanical malfunction or failures that would have precluded normal operation. The airplane sustained substantial damage to the fuselage and both wings. According to hospital records, the pilot was taken to the emergency room by emergency medical services following the accident. The pilot reported not remembering the events leading up to the accident. The pilot had a small forehead abrasion without acute injury findings on head/brain imaging. The pilot underwent additional imaging to evaluate for injuries. According to the pilot’s neurosurgery consultation notes, magnetic resonance imaging (MRI) of his brain identified a brain tumor in the left posterior cranial fossa. The neurosurgeon discussed with the pilot the possibility that the tumor may have been connected with the symptoms the pilot described before the accident. The neurosurgeon noted that a complex seizure could not be excluded, particularly with the pilot’s reported prior history of visual problems. A routine electroencephalogram (EEG) performed at the hospital did not show any seizure activity, but was nonspecifically abnormal, with mild diffuse slowing and mild slowing in the left occipital leads compared to the right. The pilot was discharged with a plan for outpatient follow up and instructions not to drive or fly. He was diagnosed with a brain mass and injuries including closed head injury. Hospital records documented that the pilot reported a history of headaches and sometimes used over-the-counter medication on an as-needed basis. The Federal Aviation Administration Forensic Sciences Laboratory performed toxicology testing of blood and urine specimens collected during the initial postaccident medical care. No alcohol or controlled substances were detected, and no substances that were generally considered impairing were detected in the pilot’s blood.