On March 6, 1996, about 1522 eastern standard time, N7451L, a Piper PA-31-310, registered to Southeast Airmotive Corporation, veered off the side of a runway on landing at the Charlotte/Douglas International Airport, Charlotte, North Carolina. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed for the 14 CFR Part 135, non-scheduled, domestic, passenger flight. While on final approach the pilot died and a passenger landed the airplane which was not damaged. The four passengers were not injured. The flight originated from the Roscoe Turner Airport, Corinth, Mississippi, about 1400 the same day. The flight was flown by a single company pilot, and was cleared for an ILS approach to runway 18L. According to a transcript of Air Traffic Control (ATC) communications, shortly after the pilot was advised of traffic that was 3 miles ahead on approach to runway 18L, a passenger who was seated in the right front seat advised the ATC controller that "...we have an emergency with the captain." The passenger stated that while on the approach over the runway numbers, he recognized that the course deflection indicator (CDI) was fully deflected to the right, and the pilot then declared a missed approach and the flight was given a heading and altitude to fly. About 15 seconds later, he noted that the pilot released the control yoke and he was leaning back in his seat. The pilot began to have convulsions and at that time he (right seat passenger) grabbed the control yoke in front of his seat and began flying the airplane and declared a "Mayday." He advised the ATC controller that he was a single engine instrument-rated pilot and that he had not flown in 5 years. The controller gave the passenger a heading to fly to return for landing but the passenger reported that he was unable to initially disconnect the autopilot system. While maneuvering at one point the pilot inadvertently positioned the left engine mixture control to the idle cutoff position and the engine quit but the passenger repositioned the mixture control and the engine restarted. The flight was vectored for a landing on runway 36 Left, and while on final approach knowing that he could land on the runway, he pulled both mixture controls to the idle cutoff position. Both engines quit and he landed the airplane; however, during the landing roll, he realized that he did not have access to the airplane's brake system. The airplane rolled off the left side of the runway onto grass and came to rest undamaged. Review of the pilot's medical file revealed that he was last given a second class medical certificate on December 13, 1995, with the limitation that the holder should possess corrective lenses for near vision. At that time he indicated that he had no heart or vascular trouble. A post-mortem examination of the pilot was performed by J. Michael Sullivan, M.D., Pathologist, Mecklenburg County, Office of the Medical Examiner. The cause of death was listed as coronary atherosclerosis/hypertensive heart disease. Toxicological analysis of specimens of the pilot was performed by the FAA Toxicology and Accident Research Laboratory. The results were negative for carbon monoxide, cyanide, volatiles, and tested drugs. Chlorpheniramine, pseudoephedrine, and phenylpropanolamine were detected in the blood and urine. According to the pilot's wife, her husband had not expressed symptoms suggestive of heart disease. Review of the Physicians' Desk Reference revealed that chlorpheniramine maleate and pseudoephedrine HCI are found in Allergy-Sinus COMTREX. Phenylpropanolamine HCI is found in COMTREX Liquid-Gel. COMTREX is indicated to provide temporary relief of listed major cold and flu symptoms.