On November 10, 1998, 1030 central standard time, a Piper, PA-23-235 multi-engine airplane, N4927P, was landed without incident by a pilot rated passenger, when the pilot-in-command (owner of the airplane) became incapacitated, while on a practice VOR approach to the Mineral Wells Airport, near Mineral Wells, Texas. The pilot rated passenger and an additional passenger were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the Title 14 CFR Part 91 personal flight. The flight originated from the Mineral Wells Airport, approximately 0930. According to the pilot rated passenger, who was seated in the right front seat, the airplane was within 5 nautical miles of the airport and the pilot-in-command was maneuvering the airplane on a VOR approach (practice instrument approach). The pilot rated passenger stated that the pilot indicated that he was going to maneuver the airplane into a descending left turn to remain on course. "Within two to three seconds," the airplane entered a "steep descent." The pilot-in-command entered a state of unconsciousness and, subsequently, died. The 600 hour pilot rated passenger, who was rated to fly single engine aircraft, took control of the airplane. The passenger who was seated in the rear of the airplane contacted personnel at the Mineral Wells Airport over the Unicom frequency. He requested that emergency personnel be contacted and requested that a multi-engine rated pilot assist the pilot with landing procedures. The pilot rated passenger was assisted by an airline pilot via radio who was on the ground at the Mineral Wells Airport. Subsequently, the airplane landed on runway 31 without incident and emergency medical personnel met the airplane. A retired airline pilot who was on the ground at the Mineral Wells Airport reported that he assisted the pilot rated passenger with landing procedures including airspeeds, mixture, and propeller control settings. The pilot rated passenger reported that the day before the accident he assisted the pilot-in-command move a "heavy tablesaw" and he appeared normal. He then saw the pilot-in-command the morning of the accident. They had a cup of coffee together and performed the preflight inspection of the airplane. During that time pilot appeared normal and did not express any discomfort. The pilot-in-command's wife reported that she saw her husband the morning of the accident and he appeared normal and did not communicate any discomfort to her. The 63 year old, 30,000 hour pilot-in-command, who was a former airline captain, held a valid third class medical certificate, issued January 20,1998. According to FAA medical records, no EKG defect codes were entered by the examining physician. Information obtained on the pilot's personal medical history showed that he had visited a doctor in September of 1998. Memos from the doctor indicated that the pilot had high cholesterol, elevated blood sugar, and was prescribed diet and allergy medications. Results of an autopsy performed on the pilot showed that he died of natural cause. The findings were that the pilot had Atherosclerotic Cardiovascular Disease, and Cardiomegaly with Biventicular Dialation. Toxicology tests were negative.