Anyway, my intent was not to limit the discussion to the World Trade Center collapses. I think it is fair to say that many people felt betrayed because these buildings suffered progressive, global collapse, resulting in many fatalities.

I'd like to hear more opinions on other failures. The Ford Pinto and McDonnell Douglas DC-10 are two examples of vehicles that went into production despite having serious design flaws that were known internally. Both space shuttle disasters could have been averted had NASA supervisors not overruled their engineers. Three houses built in the 1980's in Edmonton slid into the North Saskatchewan River in 1999. These houses were awarded building & development permits by the City of Edmonton despite internal warnings from engineers that the slope was unstable. Who do you feel is responsible in such cases? Has an engineer done his duty if he notes a problem to his superiors and managers decide to proceed anyway?

Has an engineer done his duty if he notes a problem to his superiors and managers decide to proceed anyway?

It's a case-by-case issue of course. If the engineer submitted their finding before leaving a project and anticipated that management would do something about them, I wouldn't blame them. Although if they were over-ruled and returned to the project it becomes more hazy. I think there is an amount of culpability there, but I would be somewhat forgiving seeing as they wouldn't want to lose their job or anything.

Learned a lot in here.

What an interesting brainstorm to come across! Thank you for sharing

I think it is interesting, the ethical implications behind engineering.

Professional ethics is a very serious matter within engineering because engineers are entrusted with the safety of the public. In addition to a professional Code of Ethics (which I quoted earlier), most engineers in Canada also wear the Iron Ring as a symbol of their intention to adhere to the highest ideals of the profession.

Eric, you said you'd be somewhat forgiving because an engineer wouldn't want to risk his job. I can see your point, but engineers have to be held to a higher standard because of this position of trust they are in. A known fault that could harm the public must be addressed. If the engineer has done all that he can from within the company and knows that the problem is ignored, there is an expectation that he go to a higher authority in order to protect the public.

If the engineer has done all that he can from within the company and knows that the problem is ignored, there is an expectation that he go to a higher authority in order to protect the public.

That's fair, something should come of complacency in the failure. Of course not all the blame should rest with the engineer, as he would make an easy fall guy. Also, a company may withhold information from an engineer or use a device or structure as it wasn't intended (e.g. pushing a plane past its breaking point) which is not the engineers fault.

Of course not all the blame should rest with the engineer, as he would make an easy fall guy.

I agree. Over the past 200 years, design faults have become decreasingly common and rarely provide a major contribution to catastrophic failures today, yet it doesn't stop people from blaming designers. A good example is the crash of Alaska Airlines flight 261. In order to maintain profitability, the company was cutting their maintenance budget by laying off personnel, progressively extending maintenance intervals, and strongly encouraging their mechanics to minimize downtime of the aircraft (all things that the FAA should have paid more attention to). The NTSB investigation of the accident revealed that the plane crashed because the jackscrew that controlled the horizontal stabilizer suddenly failed, making the plane uncontrollable. The sudden failure resulted from excessive wear and a sudden shearing of the threads, which would not have happened if the mechanics had not skipped the previous scheduled maintenance item for the jackscrew (which was to lubricate it with grease). At the time the jackscrew failed, it had gone three times the manufacturer's specified interval since it was last lubricated. The manufacturer's specified interval for complete replacement of the jackscrew assembly had also been exceeded. The NTSB placed some of the blame on the FAA for not identifying "widespread significant deficiencies" which should have been uncovered during their routine evaluations. The NTSB also blamed the designers of the jackscrew assembly because it wasn't "fail safe", even though the design has very low probability of failure when the manufacturer's specified maintenance schedule is followed.

I think that such a conclusion is a little unfair to the designers. It appears that the designers had anticipated that specified maintenance intervals would probably be exceeded on occasion, but they had not considered that there could be a complete failure to maintain the jackscrew. Engineers have to be able to rely on inspectors and maintenance personnel to generally comply with their recommendations. Otherwise, what would be the point of even having recommended inspection/maintenance intervals?

What are your thoughts when you're in a building (or on a bridge) and you notice the floor feels like it's "bouncing" (i.e. vibrating)? How about if you note visible deflection in a structure (e.g. beam appears to be sagging)?

In regards to the ethics of engineering, I believe that while it may not be an engineer's legal responsibility to not go ahead with a project if his supervisor passes it, it is certainly his moral responsibility. I also think it is his responsibility to report it to the appropriate government authorities if he thinks his firm is making unsafe decisions. This may involve risking his job, and is a tough decision, but an honest engineer should hopefully find an honest company to work with.

I agree that engineers and maintenance staff (or their bosses, companies, etc) are at due fault if a device fails due to negligence but not due to unforeseen events or standards that are not in place at the time. Adam, you mentioned the Tacoma Bridge incidence. This was clearly an unforeseen element in building the bridge and the engineers are not at fault. It is a design problem that now goes in the textbooks and must be considered by all future engineers. If engineers ignore such a problem in the future, it is negligent.

If I am on a bridge and it has resonance, I don't worry too much because bridges naturally resonate. However, I do worry if there are a lot of people on the bridge and it resonates a lot or if a building bounces. I definitely worry when a beam is sagging. Last year I moved into a new apartment and my cupboards were sagging and had detached from the ceiling when they were completely empty and I immediately called the building supervisor to enforce them.