Crashes and Causes

The two fatal crashes within months of each other of Boeing 737-MAX aircraft is not the first situation where a new category of airplanes entered service with a dangerous design flaw. In 1952, the De Havilland Comet, introduced by the British Overseas Air Corporation (BOAC) as the first passenger jet, had three fatal incidents shortly after its introduction. The airplane was soon grounded and investigation determined that the structure was not sufficiently strong to withstand the cyclic pressurization and depressurization required to fly at high altitudes. The investigation and remedies took nearly six years before the Comet would again fly, but by that time Boeing’s 707 had gone into service and eclipsed the British aircraft.

The one-time U. S. aviation leader Lockheed designed and built the Electra L-188, (known as the Electra II, as it had a 1930s model of the same name), in the late 1950s. The Electra II was a turboprop, using gas turbine, rather than conventional piston, engines. It was kind of a hybrid jet-propeller, considerably more powerful than the piston-props, like the Douglas DC-7, then in wide use in the United States.

In September 1959, a Braniff Airways Electra came apart in mid-air in a thunderstorm near Buffalo, Texas on a flight from Houston to Dallas. All of the passengers and crew were killed. There was no immediate explanation for the crash. A few months later in early 1960, a Northwest Orient Electra suffered a similar fate near Tell City, Indiana, on a flight from Chicago to Miami. Again, there was no apparent reason, though by then air turbulence was suspected as a contributing factor. The aviation industry and flying public became concerned and calls were made to the FAA to ground the Electra.

At the time, few Americans used flying as their mode of long distance transportation. Private railroads still had passenger trains, though they were slowly fading from the long distance scene. The Interstate highway system was significantly reducing travel time by automobile. The airline industry was growing, but many, if not most travelers were unconvinced flying was altogether safe. There was no Twitter, and even national television news was in its infancy, and sparse. No public groundswell demanded grounding the Electra. Because of the suspected turbulence factor, experts believed that ordering speed limitations on the airplane would provide a sufficient margin of safety while the CAB (forerunner to the NTSB), Lockheed engineers, and other specialists sought the probable cause. The FAA Administrator Najeeb Halaby (whose daughter Lisa later became Queen Noor upon marrying the King of Jordan) agreed and issued speed restriction but declined to ground the Electra.

It did not take long for the investigators to find the probable cause. An obscure law of physics, known as whirl-mode flutter, was the culprit. The propellers on the turbine engines caused flutter, not unlike the wobbling of a spinning top. The propellers of a piston engine would do the same thing, but the turbines were much more powerful. The wobbling was compensated by the stiffness of the engine mounts to prevent imparting it to the wings. When flying into turbulence at a speed that caused the wings to flex at a frequency that coupled with that of the engines’ flutter, a phenomenon called harmonic coupling, the stress would cause metal fatigue and the wings could snap off. The solution was to stiffen the engine mounts. Lockheed modified all of the Electras in service and designed newer ones accordingly. No other Electra went down as a result of this cause.

The fix did not do Lockheed much good, however. The airlines and passengers lost confidence in the airplane, and pure jets, like the DC-9 and Boeing 707, much better transportation in numerous ways, were rapidly coming into service. Turboprops were passé, except for short-haul and cargo purposes.

What about the 737-MAX issue today? Well, I am not about to second guess the FAA. Grounding the aircraft may be overly cautious, but they know vastly more about the facts and circumstances surrounding the accidents than the general media and public know. A Southwest Airlines pilot, who must remain anonymous, has opined that Southwest’s pilots knew about the software problem, and how to compensate for it. Whether the pilots of the Indonesian and Ethiopian air carriers had the same information has not been disclosed as of now. One factor that could have affected those pilots’ appreciation of the issue is language. The international language of aviation is English. Manuals for aircraft manufactured in the United States are written in English. Idioms and nuances do not always translate well. Anyone reading the instruction for consumer electronic devices manufactured in Japan has seen some strange phraseology.

But there is a more basic issue. How much should computer software and the so-called “artificial intelligence” take over the judgment of trained and experienced human beings, particularly when lives and valuable property are at risk? A 2006 article in Scientific American, “The Expert Mind,” showcased a study that becoming truly expert in any discipline took ten years of experience. Airline pilots are required to have 1,500 hours to obtain an Air Transport Pilot (ATP) license and around 5,000 hours (more than 6 years minimum or around 20 hours in the air per week) to be a captain for a long haul aircraft. Computers can help with many tasks but ultimately, they are only a tool.

It appears aviation has come to a point where computers can fly a plane, from take-off to landing, making pilots redundant other than as system monitors. There are other disciplines were this phenomenon is occurring, often to our detriment. It is a point too far when bad software can actually prevent pilots from taking the stick and flying the airplane, and those pilots rely on the program to make decisions until it is too late. If it is determined to be what happened in the recent 737-MAX plane crashes, it should be a lesson for the aviation community.

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