Archives For Technical risk

Technical debt

05/09/2015 — 1 Comment

St Briavels Castle Debtors Prison (Image source: Public domain)

Paying down the debt

A great term that I’ve just come across, technical debt is a metaphor coined by Ward Cunningham to reflect on how a decision to act expediently for an immediate reason may have longer term consequences. This is a classic problem during design and development where we have to balance various ‘quality’ factors against cost and schedule. The point of the metaphor is that this debt doesn’t go away, the interest on that sloppy or expedient design solution keeps on getting paid every time you make a change and find that it’s harder than it should be. Turning around and ‘fixing’ the design in effect pays back the principal that you originally incurred. Failing to pay off the principal? Well such tales can end darkly. Continue Reading…

Interesting article on old school rail safety and lessons for the modern nuclear industry. As a somewhat ironic addendum the early nuclear industry safety studies also overlooked the risks posed by large inventories of fuel rods on site, the then assumption being that they’d be shipped off to a reprocessing facility as soon as possible, it’s hard to predict the future. 🙂

From Les Hatton, here’s how, in four easy steps:

  1. Insist on using R = F x C in your assessment. This will panic HR (People go into HR to avoid nasty things like multiplication.)
  2. Put “end of universe” as risk number 1 (Rationale: R = F x C. Since the end of the universe has an infinite consequence C, then no matter how small the frequency F, the Risk is also infinite)
  3. Ignore all other risks as insignificant
  4. Wait for call from HR…

A humorous note, amongst many, in an excellent presentation on the fell effect that bureaucracies can have upon the development of safety critical systems. I would add my own small corollary that when you see warning notes on microwaves and hot water services the risk assessment lunatics have taken over the asylum…

I was thinking about how the dubious concept of ‘safety integrity levels’ continues to persist in spite of protracted criticism. in essence if the flaws in the concept of SILs are so obvious why they still persist?

Continue Reading…

Another in the occasional series of posts on systems engineering, here’s a guide to evaluating technical risk, based on the degree of technical maturity of the solution.

The idea of using technical maturity as an analog for technical risk first appears (to my knowledge) in the 1983 Systems Engineering Management Guide produced by the Defense Systems Management College (1).

Using such analogs is not unusual in engineering, you usually find it practiced where measuring the actual parameter is too difficult. For example architects use floor area as an analog for cost during concept design because collecting detailed cost data at that point is not really feasible.

While you can introduce other analogs, such as complexity and interdependence, as a first pass assessment of inherent feasibility I’ve found that the basic question of ‘have we done this before’ to be a powerful one.


1. The 1983 edition is IMO the best of all the Guides with subsequent editions of the DSMC guide rather more ‘theoretic’ and not as useful, possibly because the 1983 edition was produced by Lockheed Martin Missile and Space Companies Systems Engineering Directorate. Or to put it another way it was produced by people who wrote about how they actually did their job… 🙂