From K4U (Chris Robbins)
 
                                 FIRE, FIRE ! 
     
    Nowadays automatic systems which make use of computers for control 
    purposes are widely used. You'll find them in everything from washing 
    machines to rolling mills. But the systems don't always work in quite 
    the way their designers intended. In most cases the results aren't too 
    catastrophic. Perhaps a wash program that ends with a tub full of 
    water, or redundant movements of a positioner. However there are 
    exceptions. Such as the case of the car assembly robot, which tried to 
    weld chunks of a saloon and an estate together. This story is by now 
    well known, if apocryphal. It may or may not have some basis in fact. 
    The tale I'm about to relate is in fact true. And although I didn't 
    experience the events myself, I'm assured by a friend who was there, 
    that they did actually happen. 
     
    A few years ago a new multi-million pound theatre was built to house 
    performances of various kinds; plays, concerts, ballet etc. A lot of 
    time, effort, and money had gone into its design and construction. As 
    with similar buildings, there were a number of safety precautions that 
    had to be taken, particularly fire precautions to protect both the 
    patrons, and the theatre itself. There had to be some means of 
    automatically detecting a fire and of sounding a suitable alarm, an 
    effective means of extinguishing fires, and adequate protection from 
    smoke and flames for those in the theatre. 
     
    Being a thoroughly modern theatre, much use was made of the very 
    latest technology. There were automatic smoke detectors, alarms 
    situated both within and without the building, and links with the 
    city's emergency services. There was a large tank on the roof to hold 
    water for the comprehensive sprinkler system, which covered both the 
    auditorium and the stage. There were vents high in the roof over the 
    scenery towers, which by suitable means, could be opened quickly to 
    disperse smoke and protect the audience from poisonous fumes and the 
    danger of suffocation. There was a huge metal roller blind of a fire 
    screen, which in the event of a fire, would come down to separate the 
    public from the stage. 
     
    Should there be a power failure, there was a standby generator that 
    would cut in of it's own accord if the normal mains supply were 
    disrupted. As an extra precaution there were backup control circuits, 
    that could take over in the event that the primary circuits failed. 
    And controlling the whole system, there was of course a computer. 
     
    One day sometime soon after the theatre had been built, there were on 
    the stage a number of musicians rehearsing for the grand opening. 
     
    A test of the efficacy of the fire system had been arranged for that 
    very same day, and was about to take place. Unfortunately nobody had 
    seen fit to warn those on stage of the impending test. So the first 
    intimation they had, was the clangour of the alarms, and the rapid 
    descent of the metal fire screen which threatened to cleave their 
    number in two, not to mention one or two individuals and their 
    instruments. Fortunately they were a quick witted bunch, for no sooner 
    had they noticed the rapidly approaching danger than they scattered, 
    leaving their instruments behind. 
     
    For some reason, the computer was unaware of the difference between a 
    test of the system and the real thing. So once the fire screen was in 
    place, it decided to turn on the sprinklers, showering both the stage 
    and the auditorium with copious amounts of water. Luckily the 
    auditorium had yet to be furnished with seating, although the carpets 
    were in place, and these got rather wet. The stage itself fared better 
    since it wasn't carpeted. But the instruments abandoned following the 
    hasty departure of the musicians, suffered grievously. Those in the 
    brass section came out of it best, although it was some time before 
    they were dry enough to be played again. The woodwind wasn't too bad 
    either. But the string section was left in a very sorry state. 
     
    They managed eventually to turn the water off and restore some sort of 
    order. Mopping up operations commenced straightaway, but even on the 
    opening night several weeks later, the carpet around the stage was 
    still slightly damp. 
     
    Some time after this, it was decided to test the air conditioning 
    system. To do this required the release of a quantity of coloured 
    smoke, in order to observe the airflows. By now the seating had been 
    installed, and in view of the previous unfortunate episode of the 
    sprinklers, the water supply to them was turned off manually, just in 
    case. It proved to be a wise move. 
     
    The smoke was denser than had been anticipated, and triggered the 
    smoke detectors. The computer activated the fire screen, which began 
    to descend. The alarms began to sound. The automatic call to the 
    emergency services was set off, and engines were dispatched at top 
    speed to the scene of the supposed conflagration. 
     
    Since the water had been turned off, there was no chance of damaging 
    the by now fully equipped auditorium. It was more of a nuisance than 
    anything else. All that was necessary was to reset the system, and 
    apologise to the fire department. 
     
    The reset button was duly pressed. But since the smoke was still 
    present, the computer would have none of this obviously erroneous 
    reset. Nothing happened. The alarms continued to sound. Somebody was 
    sent to turn off the main power supply. 
     
    Switching of the power to the whole building made things a little 
    difficult, since the major part of it was now in darkness. But at 
    least the alarms had stopped. Until that is, the backup power supply 
    cut in automatically. Nobody knew how to turn this off, so the alarms 
    continued to ring, and the computer continued to try to drench the 
    theatre with water. Restoration of the power supply solved the 
    lighting problem, but left them right back where they had started. 
     
    By now there was quite a bit of smoke about, so the computer decided 
    it was time to blow the explosive bolts which kept the smoke vents 
    closed. Bang, they dutifully went, and the vents opened. However, they 
    opened just a trifle too fiercely, tore themselves off their hinges 
    and sailed majestically through the air to land with a resounding 
    crash on the top floor of a neighbouring multi-storey car park. It was 
    just bad luck that there were cars parked there at the time, and that 
    one or two happened to be in the way as the vents landed. Needless to 
    say, the cars underwent some uncalled for restyling of their bodywork. 
     
    By now the original idea of testing the air-conditioning had long 
    since been forgotten. The one thought of all those concerned, was to 
    turn the system off. Hardware modules were frantically pulled out in a 
    vain attempt to shut it down. The computer obviously realised it had a 
    major emergency on it's hands and switched in backup modules. And as 
    more pieces of the hardware were removed it transferred control to 
    further backup units. To say that those concerned were getting a 
    little frantic would be somewhat of an understatement. To add to the 
    confusion smoke continued to pour forth. Curiously no one had thought 
    to turn it off. 
     
    Eventually, somehow, it was sorted out, and switch off the fire system 
    they did, much to to the relief of those in charge. Sadly my friend 
    doesn't know how it was done, for he'd left the building by that time. 
    Did the computer run out of backup systems? Or did some enterprising 
    fireman put an axe through it's CPU? Whatever, there were certainly 
    some red faces (and blue/green ones from the smoke) after the event. 
     
     
                                   THE END