We've so far talked about the IBM 9020 which is this big beast up here
and that really had two functions, we've talked about flight data processing
which is the information about what the aircraft intends to do
but the other major facet of this is radar data processing
so you can look at it from the point of view that the flight plan tells us what the aircraft intended to do
the radar tells us what it's actually doing
and they're not necessarily the same thing, there's all sorts of reasons why the flight
doesn't actually follow the original flight plan
it can be due to weather it can be due to congestion, there's all sorts of reasons.
This was the first time we were able to bring the two together
flight and radar data processing
but that was all this did, it just did the processing
somehow we have to display all of that lot
so we'll now toddle over here
and this is an early example of a radar data processing system.
It's called the process radar display system, and essentially what happened was
the radar information which is a pure radar plot of this particular aircraft
with no other real information associated with it
woud then be routed to this equipment, which would then
be responsible for determining which controller needed to see it
so effectively doing the routing
but then also, down the bottom here, one of the worlds earliest graphics cards!
the pdp1134, which was just simply there to take the radar data
and actually work out how to paint that onto the radar screen
vector graphics drawn rather then raster drawn
and a very early example of a graphics card
and that in turn, down a jolly great long cable
would feed to this kind of display here...
this is actually a later display but it's the same type of display
all that's in here is really the technology that is required to take the graphics generated posistional data
and actually paint it onto the screen.
These screens were outrageously expensive,
I think that they were in the tens of thousands of pounds back in the nineteen seventies
and they were also rather easy to break aswell
so we were always very very careful with these.
These are all different radars that can feed in
so you've actually got a switch up here that selects all the different radars
and because this could be running what is called bypass mode
and this is how he used to do it in the old days, the control would select whichever radar gave the best
image for the area that he was trying to work on
and those are the various en-route radars
so you'd have at least two of these screens, sometimes more of them, for each sector
so this is a sector display.
How big is a sector then?
a sector varies in size depending on what's going on
there's some sectors like for example the london TMA, terminal moving area
which is really quite small
because there's an aweful lot of stuff going on
as you get further and further afield the sectors get larger and larger.
The other thing that can happen is the sectors can change shape between different times of day and so on
so for example at night there is much less air traffic and therfore controlling it is much easier
so you can make the sectors bigger, and then as the traffic starts building up in the early morning
as the flights start coming in from across the states
you make the sectors back smaller again
and that's something else we were able to do as a result of introducing computers into it,
this idea of dynamic allocation of sector size, which before then had been really quite difficult
you might have heard of a few occasions when there's been a few hiccups with the air traffic control centers
and usually it's to do with changing the size of these sectors
but again, the code has been in there for a long time now
I think we've got pretty well all the bugs out of it.
The controller would use this roller ball to, for example, highlight a particular aircraft
and draw a vector to indicate how far away he would be in five minutes time or something like that
this predates the mouse really, but in fact, in some respects it's probably a better system
they are still using roller ball technology for radar display systems even to this day
because, it's in one place, it never moves
I was up at prestwick control center just about a year ago
and watched them using this to work out
so they've got a radar paint showing that the aircraft is such and such
and we know what speed he's going at, so we can then draw a vector which says
that's where he's going to be in five minutes time
which allows him to see if he's got any issues with collision avoidance or anything like that
and also just to get the timing sorted out, the controller is trying to vector this aircraft onto the instrument landing system
so it's a useful idea to say, it'll be at such and such place in five minutes time
or two minutes time or whatever.
So, this is a very early example of the radar display using the data from IBM 9020
that sounds ever so easy, there was actually lots and lots of steps along the way
in fact it took many years before the radar data was eally being processed by the IBM 9020
and displayed in native form on this type of display,
there was also bypass systems because, well like all of these systems we don't want it failing
so there's always standby systems and standby systems to the standby systems and so on
and a lot of that had to be implemented for the radar side of things as well.
What's the sort of refresh on something like that, how often does it refresh?
Well it's effectively being refreshed all the time because it's a vector graphics drawn system
but the radars typically rotate one rotation every four seconds
so you're only going to get an update in terms of the radar data about every four seconds
and what you actually see is, like a little, you see a blob where the aircraft is
and coming off that, there's a line, and then a box and in that box you've got information about the aircraft
its altitude, the aircraft call sign, its type, where it's going from, where it's going to, whether it's accending or decending
if you've looked at FlightRadar24 they do a very similar thing
it's actually using a thing called ADSB
which is a broadcast posistional information system from commercial aircraft
and effectively plotting that using servers and then you can pick that up on the internet
and what they've done is they've more or less followed the same kind of radar display appearance
as you would have at a control center.
Going back to our early graphics card, how many of those would there be in an air traffic control center?
I think it was something in the order of one hundred so it was quite a big investment and a lot of real estate as well
Well how much were those sorts of things costing them?
I don't know to be honest, I think they were probably in the, quite a few thousand pounds each, type of category
so there would have been large chunks of a million pounds worth of equipment there
but back in those days hardware was very expensive.
Safety first as well.
Ah yes, the whole idea was that everything was resilliant, so
and of course this wasn't the only place we were using computers,
computers were coming into air traffic control in just about every sort of capacity.
This is the kind of radar display that we have today
and essentially all the hardware that is required, all the computing and processing that's required
for this sector, is actually built into the display
now everything is connected together with fibre optic, networking isn't a problem anymore
so we can actually afford to have the processing out in the display
other than that, it's more or less the same type of display, it's a vector graphics display
because that gives you a better quality of image
and the screens are still outragously expensive.
This is the sort of thing that they'll be sitting in front of at swanwick
there's also a brand new control center up at prestwick as well which does from 55 degrees north
broadly speaking the scottish border.
What's interesting to note is, as another exaple of resilliance, is that the
prestwick, with a certain amount of hassle, could do all the work that is being done at swanick
and swanick could do all the work that is being done at prestwick.
It would take a bit of doing, but if one or other of the control centers was unable to function,
then the whole of the air traffic in the UK could be run from one or the other.
One of the things that I decided I would try and do
was to write a game where the computer played Monopoly
And you can see here the high-speed
these printers would run at 600 lines per minute.
I wrote this whole thing in assembler,
the computer would make a move
and it would then print the monopoly board
so this thing was throwing up pages like mad.