The DC-10 Got Over Its Grounding, Why Won’t The 737 MAX?

There are a number of similarities between the grounding of the DC-10 back in 1979 and that of the Boeing 737 MAX more recently. The DC-10 recovered from its issues, so why does everyone think it will be more difficult to return the 737 MAX to service? Simple Flying investigates.

The DC-10 got over its grounding. Photo: Wikimedia

The last time the FAA ordered a temporary grounding of a particular aircraft model due to a fatal accident was back in 1979 when the McDonnell Douglas DC-10 was grounded for two months. Although some passengers alluded to the DC-10 being a ‘jinxed’ aircraft, the majority still happily flew on it for many years, and even today it’s in use, often as the MD-11, for freight operations around the world.

So, if the DC-10 recovered from its grounding successfully, why shouldn’t the 737 MAX too?

What happened to the DC-10?

On May 25th, 1979, 257 passengers and 13 crew boarded a DC-10, tail number N110AA, bound for Los Angeles from Chicago. The passengers of American Airlines flight 191 were no doubt looking forward to the trip, on the comfortable triple engined, twin-aisle McDonnell Douglas aircraft, known as one of the best ways to get around the world in that era.

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However, as the plane took off from O’Hare, ground observers noticed something strange was going on. The aircraft had keeled over onto its left side, to the point where it was almost flying in an inverted position. Moments later, the aircraft erupted into a huge fireball, taking the lives of all 271 people on board, as well as two on the ground.

AA flight 191
A photographer on the ground captured an image moments before the plane exploded. Photo: Wikimedia

A keen eyed American Airlines employee who was watching from the ground saw everything unfold. The engine under the left wing had detached from its pylon, flying up and over the wing. Its path over the wing damaged the hydraulic fluid lines that keep the wing’s leading edge slats in place, causing the aerodynamic characteristics of the wing to fail.

How did this happen?

The ensuing investigation traced the issue back to a maintenance inspection which had taken place a couple of months previously. At a facility in Tulsa, Oklahoma, the DC-10’s engine had been removed from the wing, for work to take place.

According to McDonnell Douglas’s procedures, the engine should have been unmounted from the pylon before detaching the pylon from the wing. However, some carriers opted to remove the engine and pylon as a single unit, in a bid to save man-hours during the maintenance process.

Continental DC-10
Both AA and Continental had altered the procedures for maintaining the DC-10 engines. Photo: Wikimedia

Doing it this way relied on a forklift operator being precisely positioned so as not to cause damage to the pylon assembly. With the forklift driver unable to even see the pylon and wing, this was a recipe for disaster. It appears that, in the case of N110AA, they got it wrong and caused unseen damage to the attachment points of the pylon.

The aircraft continued to fly for around eight weeks, with the weakness in the assembly getting worse with every flight. Eventually, it failed, causing the worst disaster in US aviation in history.

The DC-10s grounding

DC-10s around the US were inspected, and several at American Airlines and Continental were found to exhibit the fault. Two weeks after the crash, the FAA grounded all DC-10s in its jurisdiction and introduced a regulation banning foreign DC-10s from US airspace. The type certificate was restored in July 1979 and the regulation repealed, allowing the DC-10 to fly again.

Prior to the American Airlines accident, the DC-10 had been involved in two other incidents. American Airlines flight 96 had a cargo door blow out, leading to a very narrow escape thanks to the skills of the pilots in making an emergency landing at Detroit. Again, in 1974, a cargo door blew out of a Turkish Airlines flight, leading to the plane crashing in a French forest and all 346 onboard losing their lives.

united airlines 232
The crash site of United Airlines flight 232. Photo: Wikimedia

But, even after the grounding, the DC-10 continued to have issues. A Western Airlines flight crashed in Mexico City in October 1979, and a month later an Air New Zealand service flew into a mountain, killing all 257 on onboard. Ten years after this, United Airlines flight 232 crash-landed in Iowa, killing 111 of the 296 people on board.

Despite this, the DC-10 remained a popular aircraft for both passenger and cargo operations. It was only in 2014 that Biman Bangladesh flew the very last DC-10 passenger flight, and some DC-10s are still in operation as cargo aircraft today. Clearly, the DC-10 recovered from its grounding, so can we expect the same from the 737 MAX?

The similarities and differences with the 737 MAX

The 737 MAX was grounded following two fatal accidents. When the FAA ordered the grounding of the type, it was only the third time in history that the Administration has done such a thing – the first being in relation to the DC-10 and the second time the 787 Dreamliner (which had not caused any fatalities). Despite its checkered past (and future issues), the DC-10 lived on… so how did it get over its grounding?

There are some lessons from the DC-10 which are or could be applicable to the 737 MAX. For example:

  • Rebranding: The DC-10 was, post-merger, quickly rebranded to the MD-11, which may have saved its reputation for being a dangerous plane. The 737 has already been mooted for a rebrand; could it have the same effect? (note: the MD-11 was not just a new name, but also a new plane. Various design modifications came with the rebranding, something that is not on the cards for the 737 MAX).
  • Operators were on board: Despite the crashes, operators continued buying the DC-10 and flying it all over the world. The 737 MAX has also had its fair share of post-crash orders, showing that at least some operators still have confidence in the craft.
  • Investigations were thorough: The DC-10 was gone through with a fine-toothed comb to ensure its safety. The MAX is having the same treatment. Once approved, it should, in theory, be one of the safest aircraft to fly in.
The DC-10 has lived on as the MD-11, so perhaps rebranding does work. Photo: Wikimedia

However, there are some stark differences between the two situations also, which make the situation for the 737 MAX somewhat more difficult to recover from. For example:

  • It’s a design problem: The DC-10 issue was found to be the fault of the operators, not following maintenance procedures correctly. Conversely, the issue with the MAX lies with the design and manufacture of the aircraft.
  • It’s a global issue: The malfunction of the MCAS can affect every MAX in the world. The DC-10 problem was limited to those operators who had ‘streamlined’ the maintenance process.
  • The grounding is global: The DC-10 was grounded by the FAA only. The MAX has been grounded by every aviation regulator in the world and will require the approval of every regulator to get it back in operation.
  • Social media is a thing: People are so much more connected these days, and more aware of big issues like this. Although some thought the DC-10 was a ‘jinxed’ aircraft, it’s likely that not many outside of the US were particularly aware of the issues. Added to this, once it got rebranded many wouldn’t have realized it was the same plane, albeit with some improvements. With social media as it is today, we all know which airlines are trying to hide their MAX behind another name.
  • Re-engineering won’t work: The whole problem of the MAX comes down to trying to place larger engines on an old airframe. This made it lose aerodynamic stability, leading to the introduction of (faulty) software to correct the problem. When the DC-10 became the MD-11, it was fundamentally redesigned to make it better. The 737, although much loved and very successful, has reached the end of the line in terms of updating. Any further redesign will require a completely new airframe.
  • The grounding is dragging on: The DC-10 was, relatively quickly, inspected and returned to service with a clean bill of health. The issue was clearly identifiable, easily rectified and not a fundamental flaw with the plane. The MAX, on the other hand, is the polar opposite. The longer the grounding goes on, the more flaws are found with the plane. Its return to service is getting pushed further and further back, with passenger confidence diminishing every step of the way.
737 MAX
The reintroduction of the MAX could be a whole lot more difficult. Photo: Boeing

While the 737 MAX no doubt will return to service eventually, both Boeing and the operators of the type are going to have to work very hard to restore consumer confidence. While there are some parallels to be drawn between the DC-10 and the MAX, the differences in the two situations are what will make a successful return much harder for Boeing’s best-selling jet.

  1. I don’t thing the MD-11 can be considered to be a re-brand of the DC-10; I think re-design is a better term. For example, the MD-11 has a glass cockpit for two pilots, whereas the DC-10 has an analog cockpit for two pilots + flight engineer.

    Apart from that point, the main issue for me is that the faults found on the DC-10 were “normal” engineering issues…just like the rudder issue on previous 737s, for example. What’s different about the MAX is that it has a fundamental aeronautical instability, which needs software to correct it. This may be acceptable for fighter jets (which have ejection seats), but it’s not acceptable for civil aviation. This shortcoming could, potentially, be corrected by hardware changes, but Boeing apparently isn’t (yet) willing to walk that path, because of commercial pressures. Hence, the thorough evaluation and correction following the Concorde grounding, for example, does not appear to be on the cards for the MAX.

  2. With regard to the previous comments concerning the topic of re-branding, if we consider the MD-11 to be a “continuation” or “re-incarnation” of the DC-10, then the article asks a legitimate question. But, I think we now all agree that the 737 has more-or-less reached the end of the line as regards re-incarnations.

  3. Another point that could be mentioned here:
    – Back in the 70s and 80s (in the DC-10’s heyday), flying was relatively unsafe: there were far fewer planes flying, and far more of them crashing, and that was just a fact of life that you had to deal with.
    – Nowadays, flying has become extremely safe: despite the vastly increased number of planes in the air, we have proportionally far fewer crashes. Accordingly, when an incident occurs nowadays, it’s all the more noticeable and outrageous. The MAX is certainly suffering from such a modern-day reaction (on top of Boeing’s unacceptable behavior after the crashes, and shoddy design revelations).

  4. The 737 MAX is inherently unstable aerodynamically which calls for software which should not be permissible in a civilian aircraft. Had the sensors and the software been developed properly and had the flight crews received adequate information on the system we might never have had a problem. As it is now it just seems to get worse and worse. I for one will not set foot in a 737 MAX whatever it will be renamed.

  5. Wait, the Turkish incident was partially due to a DESIGN issue with the cargo door…not sure why you say it wasn’t a design problem.

    1. The cargo door issue was rectified, and relatively easily too. The flaw with the MAX is a fundamental design problem which will take much more than a new door to fix.

  6. The DC-10 had to deal with more than maintenance issues , the cargo door was a clear design flaw in my opinion. Had the FAA in 1972 issued a airworthiness directive on this, the 1974 tragedy never would have happened.

    1. The cargo door was indeed a shortcoming. But that was a component…not the whole plane.
      The cargo door was fixed by re-designing its locking mechanism. In the case of the MAX, a mechanical re-design would require major modification to the landing gear, wing and pylon so as to get the engines into an acceptable position. That’s basically a system re-design rather than a component re-design. The alternative is to try to get MCAS working properly…but it’s open to debate whether regulators will accept that…

  7. A factor at Boeing that may have contributed to the crashes of the 737 MAX 8 is the following.

    Many of the offices where many Boeing engineers, software developers, and other technical staff work are crowded, noisy, and distracting.

    In such workplaces, the risk of making careless mistakes and of overlooking critical details increases.

    While collaboration is critical when working on something as complex as a commercial airplane, so is the need to concentrate on the many technical details.

    It it is easy to measure the cost of office space. It is much more difficult to quantify the loss of productivity that comes from a distracting workplace. Also, such work environments make it much more difficult to attract and retain the best people.

    This issue deserves to get more attention.

  8. This article is inaccurate in a number of important respects.

    The DC-10 had not only maintenance issues (which caused the American Airlines crash), but also very significant design issues (which caused the “Windsor incident”, Turkish Airlines crash and the United Airlines crash in Sioux City). There were at least three different design issues, namely the cargo door latch (Windsor, Turkish Airlines), an insufficiently robust cabin floor (Turkish Airlines) and insufficient redundancy in the control systems (United).

    By the time the MD-11 came into service, those issues had been partially solved, but the MD-11 then had different issues – underperformance, very significant instability during takeoff and landing (the cause of several crashes), and control systems issues. The MD-11 actually has a worse safety record than the DC-10, and its multiple shortcomings were a major factor in the demise of McDonnell Douglas .

    The 737 MAX has even more severe instability problems. Boeing has always tried to cure those problems with fancy software, but whether they will ever really be cured remains to be seen. In the meantime, I won’t be flying on any MAXes for a very long time, even after they return to service.

  9. You talk about the 737 Max being a design problem. I agree that the plane, which was designed at a time when an aircraft might have had to provide its own stairs at smaller airports, is probably at the end of its useful life. However, what surprises me is that no one, journalist or regulator, has asked Boeing if the MCAS system was put through an FMEA. I find this odd: a conspiracy of silence or ignorance? For those not old enough to remember, FMEA (Failure Mode Effects Analysis) was part of the aerospace design process to make sure designs failed SAFE! It was why, even when air travel was more dangerous, that aircraft were safer than your family car.

    Some of you will be old enough to remember the rather combustible Ford Pinto back in the 70s. That tragedy got Ford to embrace FMEA for its designs with the rest of the automotive industry following suit.

    Not here, and not in Flight have I seen anything which asks whether Boeing, in a rush to emulate Airbus, ignored its own safe practices and ignored an FMEA of the MCAS. I find this shocking and I am not usually shocked.

    1. This issue is addressed to some extent in the following link.
      It seems that, in the first certification, an FMEA either was not performed or was performed shoddily.
      In the current certification, an FMEA is being more thoroughly performed — by the FAA, in any case. The recent additional (processor speed) error that we heard about was apparently discovered by the FAA during this FMEA.

    2. Part of the issue may be that the FAA had two highly experienced engineers who left the FAA midway through the development of the MAX. To quote the article: “According to The Times report, FAA had two highly experienced engineers overseeing the safety of the Boeing’s flight control systems in the agency’s Seattle office. But both engineers left the FAA midway through the development of the 737 Max, The Times reported. One of the engineers the FAA named in their place had little flight control experience. The other was a newly hired engineer who graduated from graduate school just three years earlier. ”

  10. In addition to the obvious and blatant errors with calling the DC-10 a re-brand to the MD11 which the author claims to have corrected but, still says rebranded in the article. There are several other major issues not mentioned. The DC-10 was later updated to the MD10 which changed it from a 3 person cockpit crew to a 2 person cockpit crew. The MD11 was a stretch, engine change, glass cockpit update that itself is critically flawed and has resulted in several accidents due to inherent instabilities.

    See for more information on the oscillation issue that caused several hull losses, injuries and fatalities.

    Aviation is a tough business. Engineering and economics are often in conflict.

    The author seems seriously devoid of basics in the article and again a shoddy job of editing to correct basic and blaring mistakes.

    At minimum a rewrite of 2 paragraphs is required to be factually correct. I am happy to discuss in detail if the author wishes.

    Now to the reality. MOST of the flying public will NOT look at the aircraft type but they will rather look at the price. The latest generation of millennials has proven that price is the driving factor, Service, Maintenance, Reputation of carrier are all secondary when compared to price.

    I have no doubt there may be some resistance to the 737 Max but within 6 months no one will notice.. Barring any further accidents. The economics on the type are too compelling and operators will be driven. Further deliveries on the A320 familiy are too far out to take a significant portion of the order backlog. The operation of 737 Classics, 737 Next Gen, MD80s, MD90s, 757s and other types that are not nearly as cost effective will drive the adoption of the 737 Max series despite the issues.

    These basics are all assuming no further 737 Max issues that cannot be explained as pilot error, maintenance, etc. once reintroduced.

    A bigger story is going to be that in the future aircraft manufacturers are going to have a harder time getting certified as now the EU, China and other regulatory agencies are unlikely to accept the FAA certifications without adequate and in depth review. The EU and China have already stated this publicly and there is significant political benefit to this as well as both have competing home grown industries that want to both limit Boeing penetration to the market and push their types into the US markets.

    Boeing and the FAA will get the Max to market short term the real damage will be felt in the longer term as CAAC and Airbus will have other advantages in the longer term future.

  11. In this article you state that the crash of flight 191 was due to a maintenance error while the aircraft design was sound – I argue this is not the case, and that the crashes of AA191, THY981 and UA232 were all due in part to an absence of fail safe systems in the design of the DC10, similar to the 737 Max issues.

    In each of the three accidents, the real problem was a failure of the hydraulic system, caused by a collapsed cabin floor, damaged wing leading edge, or hydraulic lines damaged by fragments of a shattered turbine disc.

    In the case of flight 191, the leading edge slats should have been capable of locking in place, so as to stay in place in the event of a failure of the hydraulic system that operates them.

    In the case of flight 232 and flight 981, the hydraulic lines should have had emergency shut off valves, so that when the lines were severed the hydraulic fluid would stay in the systems and so could still operate unaffected control surfaces such as the ailerons. Instead, in both accidents, all the hydraulic fluid bled out through the severed lines, rendering all control surfaces inoperable, causing total loss of control in the case of THY981, and in the case of United 232 the aircraft was only controllable by means of engine thrust.

    Additionally, the crash of flight 981 and flight 191 were also caused by other failures that were not fail safe. The DC cabin floor should have had vents that could quickly depressurize the cabin in the event of a rapid decompression in the cargo hold, so the cabin floor would remain intact thus protecting the hydraulic lines – therefore, the cargo door on the DC10 was not designed to fail safe.
    In flight 191, the captain’s stick shaker should have been able to draw electricity from either engine, so as to still be operative in the event of losing an engine. The cockpit voice recorder should not have been drawing power from only engine 1 either, and while the of the CVR failure didn’t cause the crash, it meant vital information as to what was going on in the cockpit was lost forever.

  12. I posted a comment earlier today, and it has not appeared in the comments section – I hope it has been recieved?

    1. Hey Manus, sometimes comments get sent for moderation. It would appear that yours was one of them, however, it is now live on the website.

  13. Thanks very much, also apologies for the grammar errors in my reply, was typing rather fast so didn’t see them, think you can work out what I’m saying anyway.

  14. The difference is Boeing is now viewed as a greedy manufacturer that placed priority on its bottom line rather than the safety of passengers and crew. It wasn’t upfront with its customers and the pilots that fly its products. The public is understandably enraged about it. McDonnell Douglas, as to my knowledge, wasn’t guilty of this.

  15. Might be interesting to compare also with the DeHaviland Coment…it too was grounded after the second crash.
    It took four years for de Havilland to get the redesigned Comet re-certified for commercial service…note “redesigned”.

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