Quality must be considered as embracing all factors which contribute to reliable and safe operation. What is needed is an atmosphere, a subtle attitude, an uncompromising insistence on excellence, as well as a healthy pessimism in technical matters, a pessimism which offsets the normal human tendency to expect that everything will come out right and that no accident can be foreseen — and forestalled — before it happens
Bruce Schneier has a new book out on the battle underway for the soul of the surveillance society, why privacy is important and a few modest proposals on how to prevent us inadvertently selling our metadata birthright. You can find a description, reviews and more on the book’s website here. Currently sitting number six on the NYT’s non-fiction book list. Recommend it.
Or how to avoid the secret police reading your mail
Yaay! Our glorious government of Oceania has just passed the Data Retention Act 2015 with the support of the oh so loyal opposition. The dynamics of this is that both parties believe that ‘security’ is what’s called here in Oceania a ‘wedge’ issue so they strive to outdo each other in pandering to the demands of our erstwhile secret secret police, lest the other side gain political capital from taking a tougher position. It’s the political example of an evolutionary arms race with each cycle of legislation becoming more and more extreme.
As a result telco’s here are required to keep your metadata for three years so that the secret police can paw through the electronic equivalent of your rubbish bin any time they choose. For those who go ‘metadata huh?’ metadata is all the add on information that goes with your communications via the interwebz, like where your email went, and where you were when you made a call at 1.33 am in the morning to your mother, so just like your rubbish bin it can tell the secret police an awful lot about you, especially when you knit it up with other information. Continue Reading…
The Germanwings A320 crash
At this stage there’s not more that can be said about the particulars of this tragedy that has claimed a 150 lives in a mountainous corner of France. Disturbingly again we have an A320 aircraft descending rapidly and apparently out of control, without the crew having any time to issue a distress call. Yet more disturbing is the though that the crash might be due to the crew failing to carry out the workaround for two blocked AoA probes promulgated in this Emergency Airworthiness Directive (EAD) that was issued in December of last year. And, as the final and rather unpleasant icing on this particular cake, there is the followup question as to whether the problem covered by the directive might also have been a causal factor in the AirAsia flight 8501 crash. That,if it’s the case, would be very, very nasty indeed.
Unfortunately at this stage the answer to all of the above questions is that no one knows the answer, especially as the Indonesian investigators have declined to issue any further information on the causes of the Air Asia crash. However what we can be sure of is that given the highly dependable nature of aircraft systems, the answer when it comes will likely comprise an apparently unlikely combinations of events, actions and circumstance, because that is the nature of accidents that occur in high dependability systems. One thing however is for sure, there’ll be little sleep in Toulouse until the FDRs are recovered, and maybe not much after that….
if having read the EAD your’e left wondering why it directed that two ADR’s be turned off it’s simply that by doing so you push the aircraft out of what’s called Normal law, where Alpha protection is trying to drive the nose down, into Alternate law, where the (erroneous) Alpha protection is removed. Of course in order to do so you need to be able to recognise, diagnose and apply the correct action, which also generally requires training.
The more things change, the more they stay the same…
The Saturn second stage was built by North American Aviation at its plant at Seal Beach, California, shipped to NASA’s Marshall Space Flight Center, Huntsville, Alabama, and there tested to ensure that it met contract specifications. Problems developed on this piece of the Saturn effort and Wernher von Braun began intensive investigations. Essentially his engineers completely disassembled and examined every part of every stage delivered by North American to ensure no defects. This was an enormously expensive and time-consuming process, grinding the stage’s production schedule almost to a standstill and jeopardizing the Presidential timetable.
When this happened Webb told von Braun to desist, adding that “We’ve got to trust American industry.” The issue came to a showdown at a meeting where the Marshall rocket team was asked to explain its extreme measures. While doing so, one of the engineers produced a rag and told Webb that “this is what we find in this stuff.” The contractors, the Marshall engineers believed, required extensive oversight to ensure they produced the highest quality work.
And if Marshall hadn’t been so persnickety about quality? Well have a look at the post Apollo 1 fire accident investigation for the results of sacrificing quality (and safety) on the alter of schedule.
Apollo: A Retrospective Analysis, Roger D. Launius, July 1994, quoted in “This Is What We Find In This Stuff: A Designer Engineer’s View”, Presentation, Rich Katz, Grunt Engineer NASA Office of Logic Design, FY2005 Software/Complex Electronic Hardware Standardization Conference, Norfolk, Virginia July 26-28, 2005.
Bayes and the search for MH370
We are now approximately 60% of the way through searching the MH370 search area, and so far nothing. Which is unfortunate because as the search goes on the cost continues to go up for the taxpayer (and yes I am one of those). What’s more unfortunate, and not a little annoying, is that that through all this the ATSB continues to stonily ignore the use of a powerful search technique that’s been used to find everything from lost nuclear submarines to the wreckage of passenger aircraft. Continue Reading…
Here’s an interesting graph that compares Class A mishap rates for USN manned aviation (pretty much from float plane to Super-Hornet) against the USAF’s drone programs. Interesting that both programs steadily track down decade by decade, even in the absence of formal system safety programs for most of the time (1).
The USAF drone program start out with around the 60 mishaps per 100,000 flight hour rate (equivalent to the USN transitioning to fast jets at the close of the 1940s) and maintains a steeper decrease rate that the USN aviation program. As a result while the USAF drones program is tail chasing the USN it still looks like it’ll hit parity with the USN sometime in the 2040s.
So why is the USAF drone program doing better in pulling down the accident rate, even when they don’t have a formal MIL-STD-882 safety program?
Well for one a higher degree of automation does have comparitive advantages. Although the USN’s carrier aircraft can do auto-land, they generally choose not to, as pilot’s need to keep their professional skills up, and human error during landing/takeoff inevitably drives the mishap rate up. Therefore a simple thing like implementing an auto-land function for drones (landing a drone is as it turns out not easy) has a comparatively greater bang for your safety buck. There’s also inherently higher risks of loss of control and mid air collision when air combat manoeuvring, or running into things when flying helicopters at low level which are operational hazards that drones generally don’t have to worry about.
For another, the development cycle for drones tends to be quicker than manned aviation, and drones have a ‘some what’ looser certification regime, so improvements from the next generation of drone design tend to roll into an expanding operational fleet more quickly. Having a higher cycle rate also helps retain and sustain the corporate memory of the design teams.
Finally there’s the lessons learned effect. With drones the hazards usually don’t need to be identified and then characterised. In contrast with the early days of jet age naval aviation the hazards drone face are usually well understood with well understood solutions, and whether these are addressed effectively has more to do with programmatic cost concerns than a lack of understanding. Conversely when it actually comes time to do something like put de-icing onto a drone, there’s a whole lot of experience that can be brought to bear with a very good chance of first time success.
A final question. Looking at the above do we think that the application of rigorous ‘FAA like’ processes or standards like ARP 4761, ARP 4754 and DO-178 would really improve matters?
Hmmm… maybe not a lot.
1. As a historical note while the F-14 program had the first USN aircraft system safety program (it was a small scale contractor in house effort) it was actually the F/A-18 which had the first customer mandated and funded system safety program per MIL-STD-882. USAF drone programs have not had formal system safety programs, as far as I’m aware.