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.