Flight instructors often tell new initiates that standard procedures and federal regulations, to be mastered in full prior to the completion of training, are often written in blood. After each accident and incident, the aviation community endeavored to document and learn from the often fatal destiny of unfortunate souls. Though news coverage of notable accidents and incidents might lead one to believe otherwise, there has never been a safer era for aviation throughout its 112 year history (Tolan, Patterson, & Johnson, 2015) (Westcott, 2015), and safe pilots continue to build their knowledge in the science of aviation safety. Indeed, the process of conducting some preliminary research on a fatal crash of a private flight from Boston to Wisconsin last week led me to discover that the NTSB was publishing the results of the crash most Star Wars fans had been pondering since March.
Not long after the story broke concerning Harrison Ford’s forced landing of a World War II-era vintage airplane, specifically a Ryan ST-3KR, I argued that Ford’s mitigation of a reported engine failure appeared to be nothing less than stellar (Adama, 2015). I also stated that the cause of the forced landing wouldn’t be verified until after the official NTSB report was finalized. On Monday, July 27th, the National Transportation Safety Board posted its nine page factual report on Ford’s accident via their online aviation accident database, with the official three page probable cause statement posted Thursday, August 6 — essentially documenting that a serious fault with the plane’s carburetor caused the engine to flood and shut down during the take-off climb, while a feckless shoulder harness installation may have contributed to Ford’s serious injuries during the subsequent forced landing at the Santa Monica golf course (NTSB, Probable Cause, 2015). This blog post seeks to summarize and comment on the most relevant sections of the factual report, for those interested in learning more about Ford’s spring accident.
Ford told the NTSB that he took off normally and climbed to about 1,100 ft. before observing the engine losing power (NTSB, Factual Report Aviation, 2015, p. 1). For perspective, the critical moments in an airplane takeoff occur from the application of takeoff power at the threshold of the runway, through the roll maneuver (when raising the nose to leave the ground), and climbing to an altitude in which a safe palliation of an engine failure can occur — typically 700 to 1,000 feet above the ground. From there, the pilot typically begins to configure for a cruise climb and/or maneuvers to navigate to the destination. At 1,100 feet above mean sea level, Ford had almost reached the airport’s recommended altitude for air traffic to execute a landing at the field under normal circumstances (1,200 feet), which most likely contributed to this accident being non-fatal. The engine suffering a loss of power at a lower altitude, considering Santa Monica’s surrounding man-made infrastructure, would most likely have proven fatal.
As previously mentioned, a single-engine airplane requires approximately 1,000 feet of altitude to execute a successful turn back toward an airport, with a subsequent touchdown on the campus, if that lone engine loses power during a takeoff (Note: This is often referred to as the “impossible turn” among aviators. For a peek at challenging these notions, and how to properly train for such a possibility, see this Aircraft Owners and Pilots Association training video, filmed at their headquarters in Frederick, Maryland, the airport in which I completed my commercial pilot training). Whether the airplane can successfully glide the necessary distance depends upon a number of factors, including the pilot’s ability to maintain the airplane’s proper lift versus drag ratio, while accounting for wind direction and velocity. Ford reported to the NTSB that, while not recalling much of what occurred prior to impact with a 65 foot tree near the 8th tee of the golf course, he made sure to maintain, “…an airspeed of 85 mph [while initiating] a left turn back toward the airport” (NTSB, Factual, 2015, p. 1). Though I am not privy to the ST-3KR’s official Pilot’s Operating Handbook, in comparison to most single-engine airplanes of its size and weight, I would surmise that 85 mph is most likely this airplane’s suggested “best glide speed,” which should be maintained during an engine loss of power until just before touchdown (a certitude that would’ve been drilled considerably during Ford’s primary flight instruction). Once set up for an approach to the closest runway (Runway 3), Ford began to realize that his glide trajectory wouldn’t carry him far enough (NTSB, Factual, 2015, p. 1).
When an airplane is involved in an accident, all surviving parts are shipped to an off-site location for a thorough inspection — as Adrianne Cohen (2009) documented for Popular Mechanics. Light aircraft, both single and multi-engine types, largely employ what are dubbed normal reciprocating piston engines — sharing many of the same design features as the engine in an automobile. Piston engines are somewhat reminiscent of the body’s digestive tract: it is designed to compress and agitate a fuel and air mixture, converting it into energy to produce work (turning a propeller, for example), while the remaining unused gases are discharged via exhaust ports. Most modern piston engines, employing anywhere from four to eight cylindrical pistons, receive a mixture of fuel and air through an advanced fuel injection system — a safer and operationally efficient method. Ford’s vintage aircraft, however, uses a carburetor specifically designed for airplane reciprocating engines. This is an older method for feeding engines the essential fuel and air mixture required for firing. Outside air is driven into the carburetor, where it is mixed with a proper balance of aviation fuel and sent to the cylindrical pistons. Its proper operation is critical for delivering the correct fuel/air ratio necessary for engine operation.
In the case of Ford’s plane, the NTSB determined that the main metering jet, “…was found unscrewed from its seat and rotated laterally about 90 degrees” (NTSB, Factual, 2015, p. 4). Essentially, the artery that delivers fuel ordinarily in its proper dosage to the cylinders, over time, loosened and misaligned — sending a greater concentration of fuel toward the engine, “…through the main metering orifice” (NTSB, Probable Cause, 2015,, p. 1). When a piston engine, car or airplane, receives an improper balance of fuel and air, it can’t function properly. In this case, during the apex of his climb from Santa Monica, the engine was flooded and stopped producing power (NTSB, Probable Cause, 2015, p. 1).
A review of the engine’s maintenance logs documented a full restoration and refurbishment on May 21, 1998, which included new parts for the carburetor (NTSB, Factual, 2015, p. 4). The engine’s most recent annual inspection, a thorough and exhaustive process required of all aircraft, was conducted March 13, 2014 (NTSB, Factual, 2015, p. 2), but the NTSB noted that inspection of the carburetor’s metering jets were not a requirement, nor addressed within the manual (NTSB, Probable Cause, 2015, p. 2). Thus, while MG Aviation, Inc. — the owner of the World War II-era aircraft — appears to have complied with all maintenance requirements, certified mechanics, along with Ford, were oblivious to a burgeoning concern that slowly festered over time. One would surmise, given the high-profile nature of this accident, that future inspections of all carbureted engines will subsequently include the inspection of the metering jet assembly — another Harrison Ford contribution to the enduring safety of all aviators, most likely.
In essence, Ford’s 5,000+ hours of flying and training successfully prepared him for something that rarely occurs, as only 10% of all crashes are caused by mechanical failure (Cohen, 2009).Powered by Sidelines