The two recent Boeing 737 MAX crashes have been grimly absorbing for software developers and testers. It seems that the crashes were caused by the MCAS system, which should prevent a stall, responding to false data from a sensor by forcing the planes into steep dives despite the attempts of the pilots to make the planes climb. The MCAS problem may have been a necessary condition for disaster, but it clearly was not sufficient. There were many other factors involved. Most strikingly, it seems that MCAS itself may have been working as specified but there were problems in the original design and the way it interfaces with the sensor and crew.
I have no wish to go into all this in serious detail (yet), but I read an article on the Bloomberg website, “Boeing’s 737 Max software outsourced to $9-an-hour engineers” which contained many sentences and phrases that jumped off the screen at me. These snippets all point towards issues that concern me, that I’ve been talking and writing about recently, or that I’ve been long aware of. I’d like to run through them. I’ll use a brief quote from the Bloomberg article in each section before discussing the implications. All software designers and testers should reflect on these issues.
The commoditization of software development and testing
“Boeing has also expanded a design center in Moscow. At a meeting with a chief 787 engineer in 2008, one staffer complained about sending drawings back to a team in Russia 18 times before they understood that the smoke detectors needed to be connected to the electrical system, said Cynthia Cole, a former Boeing engineer who headed the engineers’ union from 2006 to 2010.
‘Engineering started becoming a commodity’, said Vance Hilderman, who co-founded a company called TekSci that supplied aerospace contract engineers and began losing work to overseas competitors in the early 2000s.”
The threat of testing becoming a commodity has been a long standing concern amongst testers. To a large extent we’re already there. However, I’d assumed, naively perhaps, that this was a route chosen by organisations that could get away with poor testing, in the short term at least. I was deeply concerned to see it happening in a safety critical industry.
To summarise the problem, if software development and testing are seen as commodities, bought and sold on the basis of price, then commercial pressures will push quality downwards. The inevitable pressure sends cost and prices spiralling down to the level set by the lowest cost supplier, regardless of value. Testing is particularly vulnerable. When the value of the testing is low then whatever cost does remain becomes more visible and harder to justify.
There is pressure to keep reducing costs, and if you’re getting little value from testing just about any cost-cutting measure is going to look attractive. If you head down the route of outsourcing, offshoring and increasing commoditization, losing sight of value, you will lock yourself into a vicious circle of poor quality.
Iain McCowatt’s EuroSTAR webinar on “The commoditization of testing” is worth watching.
ETTO – the efficiency-thoroughness trade-off
…the planemakers say global design teams add efficiency as they work around the clock.
Ah! There we have it! Efficiency. Isn’t that a good thing? Of course it is. But there is an inescapable trade-off, and organisations must understand what they are doing. There is a tension between the need to deliver a safe, reliable product or service, and the pressure to do so at the lowest cost possible. The idea of ETTO, the efficiency-thoroughness trade-off was was popularised by Erik Hollnagel.
Making the organisation more efficient means it is less likely to achieve its important goals. Pursuing vital goals, such as safety, comes at the expense of efficiency, which eliminates margins of error and engineering redundancy, with potentially dangerous results. This is well recognised in safety critical industries, obviously including air transport. I’ve discussed this further in my blog, “The dragons of the unknown; part 6 – Safety II, a new way of looking at safety”.
Drift into failure
“’Boeing was doing all kinds of things, everything you can imagine, to reduce cost, including moving work from Puget Sound, because we’d become very expensive here,’ said Rick Ludtke, a former Boeing flight controls engineer laid off in 2017. ‘All that’s very understandable if you think of it from a business perspective. Slowly over time it appears that’s eroded the ability for Puget Sound designers to design.’”
“Slowly over time”. That’s the crucial phrase. Organisations drift gradually into failure. People are working under pressure, constantly making the trade off between efficiency and thoroughness. They keep the show on the road, but the pressure never eases. So margins are increasingly shaved. The organisation finds new and apparently smarter ways of working. Redundancy is eliminated. The workers adapt the official processes. The organisation seems efficient, profitable and safe. Then BANG! Suddenly it isn’t. The factors that had made it successful turn out to be responsible for disaster.
“Drifting into failure” is an important concept to understand for anyone working with complex systems that people will have to use, and for anyone trying to make sense of how big organisations should work, and really do work. See my blog “The dragons of the unknown; part 4 – a brief history of accident models” for a quick introduction to the drift into failure. The idea was developed by Sidney Dekker. Check out his work.
Conway’s Law
“But outsourcing has long been a sore point for some Boeing engineers, who, in addition to fearing job losses say it has led to communications issues and mistakes.
This takes me to one of my favourites, Conway’s Law. In essence it states that the design of systems corresponds to the design of the organisation. It’s not a normative rule, saying that this should (or shouldn’t) happen. It merely says that it generally does happen. Traditionally the organisation’s design shaped the technology. Nowadays the causation might be reversed, with the technology shaping the organisation. Conway’s Law was intended as a sound heuristic, never a hard and fast rule.
a slide from one of my courses
Perhaps it is less generally applicable today, but for large, long established corporations I think it still generally holds true.
I’m going to let you in on a little trade secret of IT auditors. Conway’s Law was a huge influence on the way we audited systems and development projects.
another slide from one of my courses
Audits were always strictly time boxed. We had to be selective in how we used our time and what we looked at. Modern internal auditing is risk based, meaning we would focus on the risks that posed the greatest threat to the organisation, concentrating on the areas most exposed to risk and looking for assurance that the risks were being managed effectively.
Conway’s Law guided the auditors towards low hanging fruit. We knew that we were most likely to find problems at the interfaces, and these were likely to be particularly serious. This was also my experience as a test manager. In both jobs I saw the same pattern unfold when different development teams, or different companies worked on different parts of a project.
Development teams would be locked into their delivery schedule before the high level requirements were clear and complete, or even mutually consistent. The different teams, especially if they were in different companies, based their estimates on assumptions that were flawed, or inconsistent with other teams’ assumptions. Under pressure to reduce estimates and delivery quickly each team might assume they’d be able to do the minimum necessary, especially at the interfaces; other teams would pick up the trickier stuff.
This would create gaps at the interfaces, and cries of “but I thought you were going to do that – we can’t possibly cope in time”. Or the data that was passed from one suite couldn’t be processed by the next one. Both might have been built correctly to their separate specs, but they weren’t consistent. The result would be last minute solutions, hastily lashed together, with inevitable bugs and unforeseen problems down the line – ready to be exposed by the auditors.
Splitting the work across continents and suppliers always creates big management problems. You have to be prepared for these. The additional co-ordination, chasing, reporting and monitoring takes a lot of effort. This all poses big problems for test managers, who have to be strong, perceptive and persuasive to ensure that the testing is planned consistently across the whole solution.
It is tempting, but dangerous, to allow the testing to be segmented. The different sub-systems are tested according to the assumptions that the build teams find convenient. That might be the easy option at the planning stage, but it doesn’t seem so clever when the whole system is bolted together and crashes as the full implications emerge of all those flawed assumptions, long after they should have been identified and challenged.
Outsourcing and global teams don’t provide a quick fix. Without strong management and a keen awareness of the risks it’s a sure way to let serious problems slip through into production. Surely safety critical industries would be smarter, more responsible? I learned all this back in the 1990s. It’s not new, and when I read Bloomberg’s account of Boeing’s engineering practices I swore, quietly and angrily.
Consequences
“During the crashes of Lion Air and Ethiopian Airlines planes that killed 346 people, investigators suspect, the MCAS system pushed the planes into uncontrollable dives because of bad data from a single sensor.
That design violated basic principles of redundancy for generations of Boeing engineers, and the company apparently never tested to see how the software would respond, Lemme said. ‘It was a stunning fail,’ he said. ‘A lot of people should have thought of this problem – not one person – and asked about it.’
So the consequences of commoditization, ETTO, the drift into failure and complacency about developing and testing complex, safety critical systems with global teams all came together disastrously in the Lion Air and Ehtiopian Airlines crashes.
A lot of people should certainly have thought of this problem. As a former IT auditor I thought of this passage by Norman Marks, a distinguished commentator on auditing. Writing about risk-based auditing he said;
A jaw-dropping moment happened when I explained my risk assessment and audit plan to the audit committee of the oil company where I was CAE (Tosco Corp.). The CEO asked whether I had considered risks relating to the blending of gasoline, diesel, and jet fuel.
As it happened, I had — but it was not considered high risk; it was more a compliance issue than anything else. But, when I talked to the company’s executives I heard that when Exxon performed an enterprise-wide risk assessment, this area had been identified as their #1 risk!
Poorly-blended jet fuel could lead to Boeing 747s dropping out of the sky into densely-packed urban areas — with the potential to bankrupt the largest (at that time) company in the world. A few years later, I saw the effect of poor blending of diesel fuel when Southern California drivers had major problems and fingers were pointed at us as well as a few other oil companies.
In training courses, when I’ve been talking about the big risks that keep the top management awake at night I’ve used this very example; planes crashing. In big corporations it’s easy for busy people to obsess about the smaller risks, those that delay projects, waste money, or disrupt day to day work. These problems hit us all the time. Disasters happen rarely and we can lose sight of the way the organisation is drifting into catastrophic failure.
That’s where auditors, and I believe testers too, come in. They should be thinking about these big risks. In the case of Boeing the engineers, developers and testers should have spoken out about the problems. The internal auditors should certainly have been looking out for it, and these are the people who have the organisational independence and power to object. They have to be listened to.
An abdication of management responsibility?
“Boeing also has disclosed that it learned soon after Max deliveries began in 2017 that a warning light that might have alerted crews to the issue with the sensor wasn’t installed correctly in the flight-display software. A Boeing statement in May, explaining why the company didn’t inform regulators at the time, said engineers had determined it wasn’t a safety issue.
‘Senior company leadership,’ the statement added, ‘was not involved in the review.’”
Senior management was not involved in the review. Doubtless there are a host of reasons why they were not involved. The bottom line, however, is that it was their responsibility. I spent six years as an IT auditor. In that time only one of my audits led to the group’s chief auditor using that nuclear phrase, which incidentally was not directed at IT management. A very senior executive was accused of “abdicating managerial responsibility”. The result was a spectacular display of bad temper and attempted intimidation of the auditors. We didn’t back down. That controversy related to shady behaviour at a subsidiary where the IT systems were being abused and frauds had become routine. It hardly compared to a management culture that led to hundreds of avoidable deaths.
One of the core tenets of Safety II, the new way of looking at safety, is that there is never a single, root cause for failure in complex systems. There are always multiple causes, all of them necessary, but none of them sufficient, on their own, for disaster. The Boeing 737-MAX case bears that out. No one person was responsible. No single act led to disaster. The fault lies with the corporate culture as a whole, with a culture of leadership that abdicated responsibility, that “wasn’t involved”.
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