Crash of a Cessna 510 Citation Mustang in El Monte

The pilot reported that, while holding short of the runway, he set the parking brake while waiting for his takeoff clearance. Upon receiving takeoff clearance, he reached down to the parking brake handle and, "quickly pushed the parking brakes back in"; however, he did not visually verify that he disengaged the parking brake. During the takeoff roll, he noticed that the airplane was not accelerating beyond about 70 knots and decided to abort the takeoff. The airplane subsequently veered to the left, exited the departure end of the runway, and impacted an airport perimeter fence. The pilot reported that he must have not fully disengaged the parking brake before takeoff and that there were no mechanical issues with the airplane that would have precluded normal operation. Postaccident examination of the airplane revealed that the parking brake handle was partially extended, which likely resulted in the airplane’s decreased acceleration during the takeoff roll.