Slashdot Mirror
When Bad Software Can Kill
bhoman writes "A wrist computer that tracks and calculates safe diving times and
limits for SCUBA divers had a dangerous software bug that may have been covered
up by company executives.
This SF Chronicle Article
details the problem, product, company, and some of the lawsuits.
According to the Chron article, company execs tried to cover up and
deny the problem for years, but their
official website
makes it look like they did a voluntary recall."
And it has extensive safety measures built into it to prevent insulin over delivery. Obviously, when you put your life in the hands of a machine, you want to make sure it works, and that when it doesn't, you're notified. If a company is guilty of covering up a problem like this, I hope they get sued out of existence and the people guilty spend some time in jail.
There are two major diving computer companies with "original" systems-- UWATEC and SUUNTO. Uwatec (named in the suit) has been known for less conservative systems; they let a diver stay down longer.
This is attractive to people who do decompression diving, because it means that they don't have to hang out shivering at 5-10m with nothing to see as long at the end of the dive.
Suunto takes a different approach, has a more conservative model, and makes it easier to force your computer to be more conservative still. Most divers don't use that function, because it is contrary to their desire to have maximum bottom time.
Proper diving procedures recommend using two different computers, and always relying on the more conservative unit for your decompression limits. (Assuming that you are doing a computer-only dive and not a table dive.) When your life is at stake, you have to assume that equipment has problems, and act accordingly.
I had a friend in the US who underwent LASIK surgery. He told me that his wife, who was computer-savvy, and was watching him being operated on, saw a Win95 box dedicated to controlling the laser and the mount's stepper motors, and that the operator was repeatedly hitting ENTER to make that recurring message box with a red X disappear. She got worried but the surgery was already under way, so she didn't say anything.
...
Fortunately, his LASIK succeeded. Later on however, he went back to the hospital and asked about the operator's behaviour : the response was "well, we were worried at first, but that error message comes back every five minutes and the machine always works anyway".
Scary
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I have dealth with Healthcare Software for Pharmacy and Lab systems where a delay or missed processing of an order can be fatal to a patient. One thing I found before leaving that industry was that there was a massive migration of these systems from reliable-high uptime servers (VMS, Unix, Mainframe) to Windows client server enviroment. If you think that the Klez virus is bad in a regular office, try working in an enviroment where it brings down a server critical to patient care.
Oooooh, you're so wrong!
You can prove the correctness of a bit of code, but it's very hard, takes a long time and is highly skilled work. It becomes especially hard if you're trying to do it with a grammar for any real-world programming language and the code is anything approaching complex. For most real world cases it's simply imppossible.
Mathematical proof of a program's correctness is simply too hard and costs too much money to be applicable in the real world.
If you did a real CompSci course, such as the one I did at Cambridge University, you'll discover that "CS people" are very very far from being "code nerds". I was supervised by a couple of mathematicians for some courses who could code no Java, C++ or Perl (although one of them knew much ML). Proper Computer Science folk are seriously academic and embrace the mathematical side of the field. You can't write an optimising compiler without doing so, to name but one thing.
People don't "ignore this issue" - it's just virtually inapplicable to real world problems. Exteme programming is not "management rubbish". If you'd ever actually read a book about it and tried some of the methodology you'd appreciate that. You forget that the driving force for commerical products is pretty much how much it costs, against the feature set and speed. Provided it doesn't crash very often, that's Good Enough. Unless you're the sort of type who doesn't pay for Windows, I'd suspect most people would rather have a version for $100 that crashes once a month than a version for $1000 that crashes only once a year.
Get down off your pretentious high horse and get a clue.
Six or seven years ago, I worked with a fellow with the very British
name of Ken Appleby. He had a Spitfire, I had my '74 B, and we used
to motor out to Pickwick's Pub and throw darts after work on occasion.
Ken used to work for Lucas in the UK, specifically for a division
of Lucas that did military electronics. My favorite of his stories
was about the time he had been working on a computer-controlled
torpedo. It used magnetic core memory to store the programs, which
had the advantage of being very non-volatile as well as not susceptible
to EMP discharge.
So Ken got to ride on the boat for the first test of the torpedo that
used the computer with his program in it. Somewhere out in the North
Sea, on an R. N. cutter, Ken and his crew launched the first ever run
of this new weapon, and Ken learned a new respect for debugging...
The program was supposed to make the torpedo shoot off the boat, dive
to a depth at which it couldn't be easily detected, then circle
toward the target, climb to striking depth, and hit the target. There
were on-board sensors to detect sea level, and the torpedo was supposed
to travel at a preset distance below sea level, with constant feedback
keeping it on track.
Somehow, somewhere, Ken had multiplied one of the 3D coordinates by
a negative number, and this error soon propagated through the
transformation matrix (the mathematical construct that models 3D
space), with predictable results.
Within instants of hitting the water, the torpedo -- instead of
sinking out of visible range -- blasted up and out from the water in
a great silver fountain, then continued skipping across the surface of
the blue like some sort of deranged wingless flying fish. Worse yet,
instead of circling toward the target, it circled all right, but began
to return to the ship that launched it. Fortunately it was not armed,
but they still detonated the self-destruct on it rather than let it
slice through their ship at 50 knots or whatever rate it travelled.
Because of the non-volatile core memory, Ken was able to debug the
program from what the Royal Navy frogmen could recover from it, and
he fixed the problem for Rev 2.0.
But I must admit that the image of the torpedo, splashing happily
above the surface of the water like an aroused porpoise, is one that
returns to me in idle moments such this. What else would a Lucas
torpedo do but try to fly?
I had a scuba instructor for my first certification, Di Dieter, who had experience diving with Coustou (hope I spelled that right), he also dove the Andrea Doria on several occasions, and basically has been around. I'm sure he's had thousands of dives, perhaps approching or even exceeding the ten thousand mark, under his belt (close to forty years of diving, multiple daily dives, several hundred dives a year, including a grueling dive schedule with Coustou, and he's a dive instructor). He's a no-nonsense guy with a good dose of common sense, and has little patience with screwups.
He did it right. He taught us to dive the navy dive tables, one up, one over, plus a safety margin. This was when the recreational tables had just come out. My friend and I dove for some years after that, and never had a problem. At that time, dive computers were out for a few years, and all the dive shops, through their "train with really expensive gear so you buy it" training programs had all their students diving with computers throughout their training.
Di Dieter did it right. He trained us with the old fashioned, and RELIABLE mechanical guages, waterproof clocks/watches, and tables on waterproof material. No computers.
While computers can extend dive times because you don't spend all your time at maximum depth, you also increase risk in doing so. Whether you decide to use the dive computers or not, you should ALSO have the mechanical pressure and depth guages, and manually calculate your dives.
Solely relying on a computer for diving is sheer stupidity and absolutely reckless. The minimal increase in bottom time is not worth the risk of an embolism, or the bends, which can be a debilitating condition for the rest of your life, or even fatal.
Do it right. Manually calculate your dive, and rely on your brain, not a computer, to stay safe and not risk your life. Bring that fancy computer with you if you want, but don't trust it over basic guages.
And Di, if you're reading this, this is the dude with the 43 lbs of lead on his weight belt! Hope you're still diving. And enjoying life. Peace.