Accident Overview
On November 30, 2016, at about 1730 mountain standard time, an Aero Commander 690, registration N9175N, was substantially damaged during a runway excursion at Scottsdale Airport (SDL) in Scottsdale, Arizona. The commercial pilot, who was the sole occupant, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a maintenance relocation flight.
Landing and Excursion
The pilot reported a normal landing on runway 21. After touchdown, he began easing the power levers into reverse and applied light braking to reduce speed. While reaching for the condition levers to set the propellers to low RPM, the airplane abruptly turned to the right. The pilot applied left braking and adjusted the engines to low RPM settings to counter the veer, but the airplane continued moving toward the right side of the runway, approaching the A11 exit sign. Faced with the choice of more aggressive corrective action or leaving the runway, the pilot elected to exit onto what he perceived as a hard, smooth surface—the runway safety area (RSA). Upon entering the RSA, the landing gear sank into the rock layer, quickly bringing the airplane to a stop.
Security camera footage showed the airplane touching down near the 1,000-foot runway distance markers. About 1,300 feet further, it exited the runway near taxiway A11. The aircraft traveled approximately 50 feet into the RSA, creating deep troughs in the rock, and came to rest about 2,500 feet from the approach end of runway 1.
Postaccident Examination
A postaccident examination revealed impact damage to the left side of the fuselage, including multiple holes and dents in the cabin and window areas. A rock about 2 inches in length was embedded in the fuselage and could not be removed during the inspection. Several rocks penetrated the passenger area, with one striking the right side window from the inside. The propeller blades showed gouging on their leading edges from the midsections to the tips. The right landing gear brake rotor exhibited light gouging on the braking surface.
The flight control system was examined and all controls moved freely without restriction. The steering system operated normally when the hydraulic system was activated, and the nose landing gear tire was positioned over a grease plate. Brake actuation produced normal steering. No evidence of mechanical malfunctions or failures that would have precluded normal operation was found.
Runway Safety Area Characteristics
The RSA at the accident site consisted of smoothed river rock approximately 3 inches in size, with a depth varying from 4 to 12 inches. According to the FAA, RSAs are not designed for specific aircraft types but to provide space and time for aircraft to stop safely while avoiding fixed obstacles. They are intended to support aircraft without causing abrupt halts due to sinking. RSAs may be composed of various materials, including rocks no larger than 4 inches. The design of an RSA does not account for contact by parts other than landing gear, such as propellers, engines, or wings. RSAs have proven effective in mitigating damage, injury, and death during runway excursions and overruns.