The US National Transportation Safety Board has slammed the Federal Aviation Administration for "inconsistencies, incompleteness and inaccuracy" in its safety guidelines for air shows and air races.
Recommendations for improving the guidelines have emerged from the NTSB's ongoing investigation into the dramatic crash of an air race-modified North American P-51D Mustang on 16 September 2011, at the National Championship Air Races in Reno, Nevada. The pilot and 10 spectators were killed and 66 others seriously injured when the out of control aircraft crashed into the crowd at high speed.
There are seven safety recommendations which address race course design and layout, pre-race technical inspections, aircraft modifications and airworthiness, FAA guidance on air racing, the effects of g-forces on pilots and ramp safety issues. The recommendations have been directed to the FAA, the Reno Air Racing Association and the National Air-Racing Group Unlimited Division.
NTSB chairman Deborah Hersman has provided a detailed interim update that showed "the accident sequence initiated with an upset that preceded the separation of the left elevator trim tab by approximately 6s. Our investigation revealed that this pilot, in this airplane, had never flown at this speed on this course," said Hersman. "We are issuing a safety recommendation to ensure that pilots and their modified airplanes are put through their paces prior to race day."
Hersman added: "One key safety area highlighted during the investigation is the extensive modifications made to airplanes that race in the unlimited class - and the lack of documentation and inspection associated with those modifications. On the "Galloping Ghost" [the crashed Mustang], modifications included reducing the wing span from about 37ft to about 29ft [11m-9m], and significant changes to the flight controls - all designed to increase speed and enhance racing performance."
The Board says findings from telemetry data "showed that during the upset the airplane exceeded the accelerometer's 9g limit. While the investigation into g-forces and g-tolerance is ongoing, the photographic and telemetry evidence indicates that both the airplane and pilot experienced an unanticipated, rapid onset of high g-forces and appears to support pilot incapacitation."
The elevator trim tab separated as the pilot began to lose control during a high-g turn in front of the crowd, as it passed the eighth pylon on the 10-pylon circuit.
The NTSB continues: "The fatalities and injuries in this accident draw attention to the course design and layout. The [unlimited class] race course is designed for an average ground speed of 500 miles per hour. As pilots make the final turn toward the home pylon, the trajectory of the airplane is in the direction of the spectators in the box seats and grandstands."
The Board estimates the Mustang's airspeed was 480kt (890km/h).
Source: Flight International
