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By Doug Herlihy
For The Sentinel 

Goldendale aviator looks at 737 Max 8 aircraft crashes

Two crashes of the same aircraft type in a brief time span prompted Goldendale aviator and renowned aviation safety expert Doug Herlihy to take a closer look at what happened.


March 20, 2019

Ethiopian Air Flight 302 dove steeply into the desert near Addis Ababa on Sunday, March 10, killing all 157 aboard. This disaster followed a similar dive of Lion Air Flight 610 into the Java Sea near Jakarta on October 29, 2018, killing all 189 aboard. A total of 346 lives were lost in these two yet unsolved crashes of new Boeing 737 Max 8 airplanes.

With the loss of two Boeing 737 Max 8 airliners within six months for reasons not yet understood, the FAA has grounded these airplanes operated by U.S. carriers. Other countries already have done likewise. Without a doubt, Boeing delivers a first-rate airplane to its airline customers. Their technology, testing, and quality control are arguably the best in the industry. US commercial aviation has enjoyed an almost unbelievable safety record in the last ten years. So why, suddenly, would we see the loss of two of the new Boeing 737 MAX series? Is it an aircraft systems failure, an aircrew failure or a combination?

In my opinion, as a former NTSB investigator and as a captain with 18,000 hours' experience spanning over 50 years in the cockpit, there may be several subtle issues at play. Without disparaging the capabilities of foreign pilots, many of whom are undoubtedly outstanding, as an investigator I must study subtle differences in training, technical knowledge of complex flight management systems, cockpit communication, and crew resource management (CRM). Is there a difference in essential aeronautical ability of U.S. and foreign pilots? Generally, no, but the accident sequences show that both airplanes having similar complex flight control systems with software capable of "automated decisions" were lost in "unusual attitudes"-i.e. pitch down, out of control.

To date, no U.S. or Canadian airline has experienced a loss of a Boeing 737 Max 8. Currently, U.S. carriers operate 58 of these airplanes (American Airlines and Southwest Airlines, source: Time, March 12). Canadian and Mexican airlines operate an additional 43. Certainly, pilot input is a factor. In these modern airplanes, the software of automated flight control systems is capable of "optimizing" the input to how the airplane is controlled by the pilots. That is to say, pilot control inputs that may exceed the angles or speeds are modified automatically to keep the airplane within parameters set by a manufacturer's design limits.

Can automatic override systems be turned off? That may be an important question to be answered. In these two yet unexplained crashes, the possible conflict between "automated" input (software to automatic flight control) and pilot input is a fundamental question. After a spate of upset and out-of-control losses of airliners in the 1990s (United 585, Colorado Springs; USAir 427 Pittsburgh; and others), FAA-mandated simulator training of airline pilots has included "unusual attitude training" to correctly analyze and control airplanes in sudden and violent pitch and roll. But this is perhaps only a part of the solution.

Today's manufacturers produce airplanes that are more and more automated, allowing for a wide range of flying skills, aeronautical experience, for cockpits that no longer have the luxury (and safety) of a third set of eyes, such as a flight engineer. As a result, flight crews have become less accustomed to "hand flying." Simply, airliners are much more smoothly controlled by automatic systems, providing a more comfortable ride to passengers. In fact, in Airbus airplanes, pilot positions no longer even have a steering yoke, the control being almost entirely push button. (Airbus cockpits are fitted with a small "sidestick" control as a backup to system failure).

The latest B-737 Max 8 events seem to be related to an automation issue wherein this airplane automatically corrects for a high angle of attack (known as AOA) nearing stall that will correct the attitude as the wings approach the critical stall angle. Airplane manufacturers such as Airbus, Boeing, Bombardier, Embraer, Tupolev, and even those making smaller corporate and private airplanes such as Cessna, Cirrus and Diamond, make airplanes for a broad Market, foreign and domestic. With this Market come flight crews with a variety of background and flight experience, as well as significant differences in communications, training and cockpit crew management. Essentially, modern "CRM" dictates that the captain respect the input of his first officer who acts as a "vice president of safety." How foreign crews interact and communicate is known at times to be very different than how US crews operate and failure to handle an emergency correctly can be more deadly than the emergency itself.

A word is needed about cockpit communications and precise understanding of flight manuals. The governing body for international flight operations is a United Nations oversight committee known as ICAO (International Civil Aviation Organization) that codifies communication be in the English language (air traffic control). Likewise, the great body of manuals and instructions are in the English language. But English is a second language to a large segment of the airline crew community, and that fact should not be overlooked when examining the precise understanding of airplane operating handbooks and instructions.

All airline accidents are "organizational" in nature (Professor James Reason, "The Swiss Cheese Model" of accident prevention); that is, pilot input is only one factor in an accident. Technology, crew pairing (the captain of Ethiopian Air 302 had 8000 hours experience, but his copilot had but 200 hours'), the extent of training, and many other factors play a role in all accidents. An investigator must question the likelihood of a 200-hour pilot questioning the actions of his captain, or even offering effective safety input. Essentially the captain was flying alone when the accident event occurred.

All pilots react to emergencies by two basic principles: the Principal of Primacy and the Principle of Recency. If we, as pilots, have not recently practiced, reviewed and refreshed our skills in dealing with a sudden event, we must fall back on the "primacy" of our fundamental training, i.e., that which we practiced in early flight training or last year's simulator experience. Immediate reaction to a nose pitch anomaly, be it from software or hardware malfunction, wake turbulence or wind shear, microburst or thunderstorm cell, is critically essential, but may be something rarely, if ever, practiced, upon which skill set will the crew rely? There can be no substitute for highly proficient flight crews with sharply honed, recently practiced skills.

In summary, and certainly with more questions than answers, while Boeing works to sort out the technical aspects of the possible flight control system anomaly in the Boeing 737 Max 8 airplane, is it possible that the failure of the "human system" to interact correctly with the automated system may play heavily in these accidents?

Doug Herlihy, Air Safety Investigator

Aviation Forensics LLC

Former Operations Group Chairman, NTSB


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