Lightning from a Clear Sky: The 2011 Reno Air Races crash
On the 16th of September 2011, thousands of people turned out to watch the 47th annual Reno Air Races, a unique competition between a handful of the most elite stunt pilots in the United States. But as the motley assortment of modified WWII fighters tore around the 13-kilometer (8-mile) racetrack, something went terribly wrong: traveling at more than 650km/h (400mph), Jimmy Leeward’s P-51 Mustang Galloping Ghost suddenly pitched up, rolled over, and dived straight into the stands, sending shards of debris ricocheting through the assembled crowd. The brutal crash killed Jimmy Leeward and 10 spectators, while more than 60 people were injured, making it the worst air show disaster in the United States in nearly 40 years. Remarkably, a group of National Transportation Safety Board investigators witnessed the crash, in what was probably a first in the agency’s history. Within minutes of the disaster, they set about finding the cause, opening an investigation that led the NTSB into the heart of a world it rarely visited. The conclusions they came to not only shed light on the factors that led to the crash, but would also lead to changes that made air races safer for everyone who enjoys them.
[WARNING: Although this article does not show visible fatalities, it does include footage that some readers may find disturbing.]
The National Championship Air Races (commonly known as the Reno Air Races) are a series of airborne racing events held every year at Reno Stead Airport in Reno, Nevada. Billed as the “world’s fastest motorsport,” the races consist of five different aircraft categories, including biplanes and jets, as well as a sixth “Unlimited” class, where any propeller plane with any number of custom modifications may enter. Professional stunt pilots fly the planes around a marked race course over the Nevada desert at altitudes as low as 100 feet and at speeds that can exceed 800km/h (500mph). Spectators can gather at a set of grandstands and a box seating area alongside the course to watch the planes race past. The event typically fosters a party atmosphere, with beer coolers, food, and other amenities spread out across the airport’s parking apron.
Among the pilots competing in the Unlimited class in 2011 was James “Jimmy” Leeward, a 74-year-old professional pilot from Florida who had been participating in the Reno Air Races since the 1980s. Although he would have been too old to fly for a commercial airline, Leeward was in good health and had lost none of his competitive spirit — in fact, in 2011, he was in the race to win it.
Leeward’s plane was a North American P-51D Mustang, a World War II-era single-pilot long range fighter that he had named Galloping Ghost. Galloping Ghost was originally built in 1944 for the US Air Force, but by 1946 it had outlived its usefulness and was sold as surplus to a private owner. It soon found a career in racing, winning multiple races in the late 1940s and continuing under several owners until 1983, when it was purchased by Jimmy Leeward. Leeward raced the aircraft (then called Specter) for several years, until a series of engine failures and a crash landing compelled him to put the plane into long-term storage in 1989. It was not until 2007 that he decided to restore the plane and race it again, beginning with the 2009 championship.
In preparation for his return to the Reno Air Races, Leeward made a series of modifications intended to increase the plane’s top speed. He installed a new Rolls Royce Merlin V12 engine with a custom cooling system fed from a wing tank; built a new custom canopy; and cut 1.24 meters (4 ft 1”) off of each wing to save weight and make the plane more aerodynamic. He also made several changes to the pitch controls, particularly the elevator trim system. The P-51 Mustang has a trim tab on the trailing edge of each elevator, which can be moved separately from the elevator in order to hold it in a particular position, allowing the application of a continuous pitching force without sustained input from the pilot. The stock Mustang had a purely mechanical pitch trim system; however, Leeward replaced it with an electric trim motor attached to the left elevator trim tab. He disconnected the right trim tab from the system completely and fused it to the elevator, leaving him with trim control only on the left side. He also increased the size of the elevator counterweights, which made the pitch controls more sensitive. Besides these changes, numerous other modifications were made to the aircraft structure and flight controls, most of them without any accompanying documentation. Experts would later estimate that Galloping Ghost was one of the most heavily modified P-51 Mustangs ever to fly.
Of particular interest among the mechanical oddities of the plane are several details of the left elevator trim tab. Three hinges affixed to the main spar of the trim tab and the aft spar of the elevator formed the joint between the two control surfaces. A screw, secured with a locknut, connected each hinge to the trim tab.
Over time, the motion of the trim tab up and down causes wear and tear on the locknuts, and they must be replaced periodically. But on Galloping Ghost, the locknuts on the left trim tab had not been replaced since at least 1985, and their threads had worn away to the point that they no longer applied any gripping force to the screws. The screws consequently had room to wiggle back and forth in flight, which caused fatigue cracks to develop in the inboard screw near where it passed through the locknut. By 2009, these cracks had been growing undetected for a number of years.
Jimmy Leeward did not finish his modifications in time to fly Galloping Ghost in the 2009 race, but he was able to enter in 2010, and he flew several times before the final heats were cancelled due to wind. When the 2011 races rolled around, he was more than ready to prove himself and his plane. He told friends that during a test flight he had managed to break 500 miles per hour (800km/h), within spitting distance of the Unlimited Class speed record if he could reproduce that performance on the racecourse. Galloping Ghost was unquestionably a contender for the grand prize — a hefty sum of one million dollars.
Leeward soon passed the qualifier with a fourth place finish, easily ensuring him a spot in the Unlimited Class gold heat on the 16th of September. After the qualifying round, he reported to his ground crew that the elevator trim tabs had a little too much “free play,” and mechanics found that the screws had started to work loose in the supposedly immobile right trim tab. They tightened the screws and called the job done, without checking to see if the left tab might have the same problem. Little did anyone know that the structural strength of the left side trim tab attachment screws had degraded almost to the breaking point.
On the afternoon of the 16th of September 2011, Jimmy Leeward taxied Galloping Ghost out to the runway at Reno Stead Airport in front of thousands of cheering fans. Numerous modified warbirds followed, including several other P-51 Mustangs. In a nearby building, Leeward’s ground team monitored a computer screen displaying telemetry data beamed directly from Galloping Ghost, confirming that everything was in good working order. Elsewhere, police and fire services stood on standby, watching the race for any sign of an emergency. A group of National Transportation Safety Board investigators also watched from the stands, pausing to enjoy the race after an afternoon spent raising awareness about race safety.
At around 4:20 p.m., the planes took to the air, circling in formation around the nine pylons marking the course, until the announcer at last called out, “You have a race!”
As the planes accelerated onto the first straightaway, Leeward allowed himself to fall toward the back, planning to use his usual strategy of overtaking everyone from behind. By the second lap, the strategy appeared to be working, as he started edging his way back up through the field. By lap three of the six-lap race, he had climbed to third place, just behind Voodoo, another modified P-51 Mustang.
Then, as Leeward passed Pylon 8, disaster struck. He hit the wake from Voodoo and rolled sharply to the left, an excursion which he quickly moved to correct by pushing his control stick to the right. Coincidentally, it was at that exact moment that the left trim tab began to fail. The cracked inboard attachment screw had lost so much stiffness that the trim tab developed a motion known as “flutter.” Flutter is a rapid oscillation of a flight control surface that occurs when an aerodynamic force amplifies the structure’s natural vibrations. Severe flutter generally requires two things: speed, and a lack of structural stiffness. With one screw cracked and two loose, the attachments lacked enough stiffness to dampen the flutter, and it rapidly grew in amplitude over a period lasting less than one second. The final, massive movement overstressed the mechanical linkage connecting the trim tab to the actuator, causing it to break and allowing the trim tab to rotate far beyond its normal maximum nose up position of 13 degrees. The huge input sent Galloping Ghost into a climb so quickly that the plane pulled a dizzying 17.3 G’s, far beyond human tolerance levels; Leeward’s blood rapidly flowed away from his brain, rendering him immediately unconscious.
As Galloping Ghost shot up and away from the race course, it continued to roll to the right as its incapacitated pilot leaned into the controls. Almost at the moment the plane reached its zenith, the fatigued inboard attachment screw finally broke, and the left elevator trim tab departed the airplane. Galloping Ghost began to pitch down and veer to the right — toward the crowd of thousands of spectators. Terrified fans barely had time to duck as the plane, traveling at more than 800km/h (500mph), dived straight at them from above. Just nine seconds after the upset began, Galloping Ghost slammed nose first into the box seating area in front of the grandstands, throwing a grisly geyser of debris high into the air. A wave of shattered aircraft wreckage tore through the assembled crowd as pieces of the plane, deck chairs, beer bottles, and people were hurled in every direction. In a split second, a day at the races had turned into an unimaginable disaster.
The ranking officer on scene had already sounded the alarm even before the plane hit the ground, and firefighters rushed to the scene before the debris had time to settle. The race announcers had nearly been wiped out themselves, but to their credit they remained calm and began issuing evacuation orders to the crowd while sitting just meters from the carnage. Paramedics hurried to triage patients as shocked and bloodied spectators staggered away from the scene. Survivors suffered from severe lacerations, missing limbs, and other grievous injuries. Others lay dead on the apron; at that stage, no one knew for sure how many had been killed. Pieces of the plane were scattered everywhere, mixed in with smashed chairs, wrecked coolers, and a sea of spilled aviation fuel and alcohol. As the wounded were loaded onto ambulances, authorities shut down US highway 395, the main artery through the region, to make way for emergency services.
By the time the scene had been cleared and the critical patients stabilized in hospital, 11 people were dead, including pilot Jimmy Leeward, and at least 69 others were injured. It was the deadliest US air show accident since 1972, and one of only a handful that involved fatalities among the spectators. A thorough investigation would be needed to uncover the cause — and to determine whether the Reno Air Races could be made safer in the future.
Because NTSB investigators were already on the scene, the investigation began just minutes after the crash. This was most likely the only case in the history of the NTSB in which investigators actually witnessed the crash they would be asked to investigate, and their presence throughout the sequence of events gave them a head start on finding the cause. Also helpful were dozens of photographs and videos taken by fans, covering everything from the first sign of trouble to the moment of impact. These photos revealed that the left trim tab had separated in flight, and it was soon recovered near pylon 9, well away from the rest of the wreckage.
Investigators also found the hinge assemblies to which the trim tab had been attached, and there they made a critical discovery. The locknuts securing the attachment screws had yellow paint on them, even though the plane had not been painted yellow since 1985, indicating that the nuts were at least 26 years old, far beyond their intended lifespan. A detailed analysis of the trim system, the photographs, and the telemetry data revealed the basic sequence of events: first, the worn locknuts stopped securing the attachment screws, allowing them to move back and forth; then the inboard screw started cracking, decreasing its strength even further; and finally, during the final race, its stiffness decreased to the point that uncontrolled flutter occurred, leading to the massive pitch up and separation of the trim tab. The G-forces knocked Leeward unconscious immediately, preventing him from regaining control.
However, several more subtle factors also played a role in the crash. One aspect that warranted closer scrutiny was whether any of the modifications to the plane could have contributed to the failure. Unfortunately, investigators quickly discovered that almost all the modifications to Galloping Ghost had no associated design drawings, strength analyses, flight testing data, or other documentation. Nor did Leeward’s ground team know the purpose of all of the modifications that he had made. Only by observing the wreckage could investigators understand what exactly he had done to the elevator trim system. They found that in this area, his modifications did play a role: by making only the left trim tab controllable, he increased the stress on that tab’s attachment points, accelerating the degradation of the screws. This change also exacerbated the pitch excursion because the right trim tab could not be used to counter it, doubling the rate of pitch change and the associated G-load. It was possible that if both trim tabs had been controllable, Leeward might not have lost consciousness during the maneuver, allowing him to regain control or at least steer the plane away from the crowd.
The trim tab changes weren’t the only modifications that the NTSB found to have generated negative effects. Photos from the day of the race also showed that some of the structural changes were causing undesirable warping of the fuselage skin, and the custom canopy had started to partially delaminate from the windscreen. It was at this point that the NTSB realized there was no evidence Leeward had ever properly flight tested his modifications or informed the appropriate authorities about them. Both the Federal Aviation Administration and the Reno Air Racing Association (RARA) required pilots to report any major modifications prior to the plane’s participation in the race, but it appeared that Leeward had only reported the custom engine cooling system and not any of the changes to the structure or flight controls. Even for the modification that he did report, FAA rules for experimental aircraft required him to flight test it for at least 3 hours with 3 takeoffs and landings, but available records showed that this minimum level of testing was never accomplished.
Excluding the cooling system, there was no evidence to suggest that Leeward’s other modifications had undergone any flight testing at all. In his application to fly Galloping Ghost in the 2009 race, he indicated that his plane had undergone a “major modification” since it last raced in 1989, but RARA’s technical committee never inspected it because Leeward withdrew his application before they could do so. In 2010, Leeward’s application did not mention any major modifications since the last race, even though this was false; the NTSB thought that he might have mistakenly believed he only had to report modifications made since his last application. As a result, race authorities never inspected any of the modifications to Galloping Ghost prior to its participation in the 2010 and 2011 races. Had extensive flight testing and proper inspections been carried out, many of the undesirable side effects of the modifications might have been discovered, including the problem with the trim tab attachment screws. The NTSB also noted that several other opportunities to prevent the crash had been missed during routine inspections. Mechanics had evidently tightened the attachment screws on both trim tabs multiple times over the recent history of the airplane, including just four days before the crash, but no attempt was made to discover why they kept coming loose.
Finally, the NTSB looked into the safety of the race itself, and found that federal guidance on air races contained several glaring inconsistencies. Most critically, an FAA order specified a minimum distance of 1,000 feet laterally between the spectators and the race course, while a 1990 advisory circular specified a minimum distance of only 500 feet. The Reno Air Races were in compliance with the advisory circular but not the order, with a distance of approximately 750 feet (230m) between the course and the seating area. Had 1,000 feet of separation been provided, Galloping Ghost would have struck open ground. The confusion surrounding which piece of FAA guidance to follow therefore contributed directly to the spectator fatalities. The NTSB also noted that there was a fuel truck parked on the ramp near the seating area, and although it was not damaged in the accident, the tragedy could have been much worse if it was. Clearly, changes would need to made to keep spectators safe in the future.
Fortunately, RARA took the NTSB’s safety proposals seriously. Race organizers and pilots alike recognized that while the sport is inherently dangerous — prior to 2011, 19 pilots had died while racing at Reno — allowing that danger to extend to the spectators was unacceptable. As a result of the NTSB’s recommendations, RARA made several changes for the 2012 Reno Air Races. Participants in the Unlimited class (where all modifications are legal) now have to submit a full engineering analysis to race authorities before receiving approval for racing with major modifications. The distance between the spectators and the race course has been increased to more than 1,000 feet laterally. The fuel truck is now parked farther from the spectators and from the race course. Participating pilots now receive training on high-G maneuvers and how to stay conscious during them. Any discrepancies noted in pre-flight inspections must now be fully corrected and the plane re-inspected before it can participate in a race. And the FAA has issued a new order superseding the old guidance and clearly laying out the rules that govern air racing.
Today, the Reno Air Races continue to thrill fans with the same speed, noise, and excitement as before — but with a much higher level of safety. Not only have no more spectators been hurt in accidents, the more rigorous engineering rules have protected pilots as well. In the nine years since the crash, only one pilot has died, compared with one death every 2.5 years on average in the period from 1964 to 2010. While the death of any pilot is tragic, air racing is dangerous, and like any other extreme sport, it will never be 100% safe for those who choose to partake in it. As long as the safety of non-participants can be ensured, the sport has the right to remain. It may be hoped that with the passage of time, the Reno Air Races will continue to show that it is possible to preserve the features which make air racing exciting while also ensuring the highest level of safety.
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