Ethiopian, Lion Air, and the 737 MAX

What a mess. Boeing is getting knocked around by everyone from members of Congress to late-night comedians. The MAX’s certification program is under scrutiny, airlines are canceling orders, and passengers everywhere are scared. The FAA is facing accusations that it took far too long to order the MAX’s grounding (after numerous other countries had already done so), and that it basically permitted Boeing to self-certify an unsafe aircraft.

We keep hearing, too, about what a horrible black mark this is not merely against Boeing, but against American aviation’s place in the world. We are no longer the global leader in air safety, no longer the “gold standard,” whatever that means exactly, as several articles have described it. This is maybe just another example of the weird phenomenon known as American exceptionalism, but each time I hear it, I keep going back to the DC-10 fiasco in the 1970s.

Cockpit Confidential: ... Smith, Patrick Best Price: $4.42 Buy New $10.00 (as of 08:40 EST - Details) In 1974, in one of the most horrific air disasters of all time, a THY (Turkish Airlines) DC-10 crashed after takeoff from Orly Airport outside Paris, killing 346 people. The accident was traced to a faulty cargo door design. (The same door had nearly caused the crash of an American Airlines DC-10 two years earlier.) McDonnell Douglas had hurriedly designed a plane with a door that it knew was defective, then, in the aftermath of Paris, tried to cover the whole thing up. It was reckless, even criminal. Then, in 1979, American flight 191, also a DC-10, went down at Chicago-O’Hare, killing 273 — to this day the deadliest air crash ever on U.S. soil — after an engine detached on takeoff. Investigators blamed improper maintenance procedures (including use of a forklift to raise the engine and its pylon), and then found pylon cracks in at least six other DC-10s, causing the entire fleet to be grounded for 37 days. The NTSB cited “deficiencies in the surveillance and reporting procedures of the FAA,” as well as production and quality control problems at McDonnell Douglas.

That’s two of history’s ten deadliest air crashes, complete with design defects, a cover-up, and 619 dead people. And don’t forget the 737 itself has a checkered past, going back to the rudder problems that caused the crash of USAir flight 427 in 1994 (and likely the crash of United flight 585 in 1991). Yet the DC-10, the 737, and America’s aviation prestige along with them, have persevered. If we survived the those scandals we can probably manage this. I have a feeling that a year from now this saga will be mostly forgotten. Boeing and its stock price will recover, the MAX will be up and flying again, and on and on we go. This is how it happens.

There’s also a lot being made of the FAA’s more or less outsourcing aircraft certification to Boeing. This is frustrating, and ironic, because air travel has never been safer, and it’s partly because, not in spite of, the close relationship and collaborative efforts between regulators, airlines, manufacturers, pilot groups, and so on. (A good example is the self-reporting program between pilots and FAA, which has been very successful and has kept dangerous trends from being driven underground.) Bear in mind how much these parties stand to lose should a tragedy occur. A crash can destroy an airline outright. It’s in the interest of all these entities to play things as safely as possible.

Did something go wrong in the 737 program? Are Boeing and the FAA jointly responsible? Probably. But I don’t believe anybody was intentionally reckless. That’s an important distinction, and for the most part the relationships between industry and regulators has been a productive one. You can’t say that about banking, perhaps, but in aviation it seems to work. The remarkable safety record we’ve enjoyed over the past twenty years bears that out, absolutely.

For the airline passenger, these can seem like scary times. Air crashes, perhaps more than any other type of catastrophe, have a way of haunting the public’s consciousness, particularly when the causes are mysterious. My best advice, maybe, is to turn off the news, take a step back, and try to look at this through a wider lens. The fact is, Lion Air and Ethiopian notwithstanding, air travel has never been safer than it is today. Two fatal crashes in five months is tragic, but in decades past it wasn’t unusual to see ten, fifteen, or even twenty air disasters worldwide in a given year. Nowadays, two or more is downright unusual. Here in the United States there hasn’t been a large-scale fatal crash involving a mainline carrier in nearly twenty years — an absolutely astonishing statistic. There are far more planes, carrying far more passengers, than ever before, yet the accident rate is a fraction of what it once was.

I have a question, however:

One of the things I can’t help wondering about is why the 737 MAX needed to exist in the first damn place. Somewhere deep down, perhaps the heart of this whole fiasco is stubbornness — that is, Boeing’s determination to keep the 737 line going, variant after variant, seemingly forever. Instead of starting from scratch with a new airframe, they took what was essentially conceived as a regional jet in the mid-1960s, and have pushed and pushed and pushed the thing — bigger and bigger engines, fancier avionics and more seats — into roles it was never intended for.

For a jet of its size, it uses huge amounts of runway and has startlingly high takeoff and landing speeds. The passenger cabin is skinny and uncomfortable; the cockpit is incredibly cramped and noisy. I don’t care how many changes and updates the plane has undergone; at heart, it’s still a blasted 737 — a fifty year-old design trying to pass itself off as a modern jetliner. The “Frankenplane,” I call it. Look at that tell-tale nose and windscreen. Do you recognize that? It’s the 707, from 1958, unchanged.

I’m not saying this is the reason, directly, for what happened in Indonesia or Ethiopia, but is it maybe not time, at last, to move on from the 737 platform?

UPDATE: April 6, 2019

This just makes you shake your head.

What seems to be the case, based on analysis of the voice and data recorders from the doomed Ethiopian Airlines flight 302, is that the pilots did, as they should have, engage the plane’s pitch trim disconnect switches in a frantic attempt to regain control after a malfunctioning MCAS system forced the plane’s nose toward the ground. This pair of switches, on the center console near the thrust levers, killed power to the entire automatic pitch trim system, including MCAS, and should have allowed the pilots to maintain a normal flightpath using manual trim and elevator. Manual trim is applied by turning a large wheel mounted to the side of that same center console. Elevator is controlled by moving the control column forward or aft.

Yet they did not, could not, regain control. The reason, many now believe, is a design quirk of the 737 — an idiosyncrasy that reveals itself in only the rarest of circumstances, and that few 737 pilots are aware of. When the plane’s stabilizers are acting to push the nose down, and the control column is simultaneously pulled aft, a sort of aerodynamic lockout forms: airflow forces on the stabilizers effectively paralyze them, making them impossible to move manually.

Aboard flight 302, the scenario goes like this: Commands of the faulty MCAS are causing the automatic trim system to push the nose down. The pilots, trying to arrest this descent, are pulling aft on the control column. Thus setting up this scenario perfectly. The trim forces are stronger than the control column forces, which is why pulling back on the column has no effect. But now, with power to the trim system shut off, they can lift the nose by manually by rotating the trim wheel aft, relieving that unwanted nose-down push. But the wheel won’t move. Believing the manual trim is itself broken, the pilots then reengaged the auto-trim. MCAS then kicks in again, pushing the nose down even further. What’s worse, as the plane’s speed increases, the lockout effect intensifies. And so with every passing second it becomes more and more difficult to recover.

The correct course of action would be to relax pressure on the control column, perhaps to the point of pushing the nose down even further. This will free the stabilizers of the aerodynamic weirdness that is paralyzing them, and allow the trim wheel to move, realigning the stabilizers to a proper and safe position. For the pilots, though, such a move would be completely counterintuitive. Instead, they do what any pilots would be expected to do under the circumstances. Turns out it’s the wrong thing, but really they have no way of knowing.

It’s possible, or probable, that the pilots of Lion Air flight 610 faced exactly the same situation, with the same result.

Apparently, pilots of older-generation 737s — long before there was MCAS — were aware of the lockout potential, and some were trained accordingly. (I flew the “classic” 737-200, briefly, about twenty years ago, but have no memory of it one way or the other.) However, as an obscure phenomenon that no pilot was likely to ever encounter, it was eventually forgotten as the 737 line evolved, to the point where no mention of it appears in the manuals of later variants.

Circles, left to right:

1. Electric trim switches. With the autopilot engaged the pitch trim system operates automatically. With the autopilot off, the pilot controls the trim by manipulating these switches forward or aft, usually with his or her thumb.

2. Trim wheel. This is the wheel that the pilot will rotate forward or aft to control trim manually.

3. The disconnect switches. These kill power to the trim system. Auto-trim and the thumb switches are now shut off; trim is adjusted using the wheel in the second circle.

UPDATE: March 29, 2019

ON MARCH 10th, Ethiopian Airlines flight ET302, a Boeing 737 MAX bound for Nairobi, crashed after takeoff from Addis Ababa, killing 157 people from more than thirty countries. Five months earlier, 189 people perished after Lion Air flight JT610 went down near Jakarta, Indonesia, under eerily similar circumstances. Both planes were brand new 737 MAX jets. Both crashed shortly after takeoff following a loss of control.

Although findings from the voice and data recorders pulled from the Ethiopian wreckage haven’t been released yet, it’s all but assumed that flight succumbed to the same flight control malfunction that brought down Lion Air. The 737 MAX has a deadly design flaw, and Boeing needs to fix it. In the meantime, all MAX jets remain grounded worldwide.

The culprit is something called MCAS, which stands for Maneuvering Characteristics Augmentation System, a system that adjusts control feel as the plane’s nose pitches upward, effectively nudging it downward.

MCAS operates in the background, transparently and automatically — there’s no on or off switch, per se — and only during a very narrow window of the jet’s flight envelope. This is not something that occurs in normal, day-to-day operation, but certification requires it for those occasions when, for whatever reason, the plane reaches unusually steep climb angles. To raise a plane’s nose, the pilot pulls back on the control column. As the nose pitches further and further upward, the control forces required to maintain this action are supposed to become heavier. This helps keep pilots, and/or the autopilot, from inadvertently stalling the plane — that is, exceeding what we call the “critical angle of attack,” at which point the wings run out of lift and the plane ceases to fly. On the 737 MAX, however, certain aerodynamic factors, including the placement of its very powerful engines, result in control forces actually becoming lighter as it approaches the point of stall. Because of this the plane would not meet certification standards. And so MCAS was engineered in to properly adjust the feel.

Thus there’s a certain beauty to MCAS — provided it works correctly. What’s happening, apparently, is that faulty data is being fed to MCAS by the plane’s angle of attack indicator — a small, wedge-shaped sensor near the plane’s nose that helps warn pilots of an encroaching aerodynamic stall. An impending stall is sensed when there isn’t one, triggering the plane’s stabilizer trim — stabilizers are the wing-like horizontal surfaces beneath the tail — to force the nose down. This sets up a battle of sorts between the pilots and the trim system until the plane becomes uncontrollable and crashes.

What leaves us stymied, though, is the fact that any MCAS commands, faulty or not, can be overridden quickly through a pair of disconnect switches. Why the Lion Air pilots failed to engage these switches is unclear, but unaware of the system’s defect in the first place, we can easily envision a scenario in which they became overwhelmed, unable to figure out in time what the plane was doing and how to correct it. From that point forward, however, things were different. “Though it appears there’s a design flaw that Boeing will need to fix as soon as possible,” I wrote in November,“passengers can take comfort in knowing that every MAX pilot is now acutely aware of this potential problem, and is prepared deal with it.”

Or so it seemed. With the Lion Air crash fresh on any MAX pilot’s mind, why did the Ethiopian pilots not immediately disconnect the trim system? Did a disconnect somehow not work? Was the crew so inundated by a cascade of alarms, warnings, and erratic aircraft behavior that they failed to recognize what was happening? Or, was the problem something else completely? This is the most perplexing part of this whole unfolding drama.

While we wait for the black box results, Boeing this week revealed a suite of hardware and software tweaks that it claims will rectify the issue. This includes incorporation of a second angle of attack indicator, and an alerting system to warn pilots of a disagreement between the two.

Ethiopian Airlines 737 MAX

The largest MAX operators in the U.S. are American Airlines, Southwest and United. Other customers include Alaska Airlines, Air China, Norwegian, FlyDubai, China Eastern and China Southern. The type is most easily recognize by its 787-style scalloped engine nacelles, which earlier 737s do not have. Ask the Pilot: Everyth... Patrick Smith Best Price: $0.10 Buy New $29.32 (as of 10:50 EST - Details)

Founded in 1945, Ethiopian Airlines is the largest carrier in Africa. Westerners hear “Ethiopia” and tend to make certain, unfortunate associations, but this is company with a proud history and a very good safety record. It flies a state-of-the art fleet, including the Boeing 787 and A350, on routes across four continents. Its training department, the Ethiopian Airlines Aviation Academy, has been training pilots for 55 years. Ethiopian’s pilots are distinguished by their handsome, olive green uniforms.

The captain of the doomed flight ET302, Yared Getachew, was a graduate of the highly competitive Ethiopian Airlines Aviation Academy, and had more than 8,000 flight hours — a respectable total. “Yared was a great person and a great pilot. Well prepared,” a former Ethiopian Airlines training captain told me.

The first officer, on the other hand, had a mere two-hundred hours. Airline training is intensive, and as I’ve written in the past, the raw number of hours in a pilot’s logbook isn’t always a good indicator of skill or talent. Nonetheless, if indeed that number is correct (it’s unclear if this refers to his total flight time, or his number of hours in the 737 MAX), that’s pretty astounding. By comparison, the typical new-hire at a U.S. major carrier has somewhere on the order of 5,000 hours. Whether the first officer’s lack of experience had anything to do with the accident, however, is another matter.

Reprinted with permission from Patrick Smith.

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