Oral History of Robert Everett - Computer History Museum

Hendrie: And so the order got changed from "erase" to "keep forever.”
Everett: Yes, that's right.
Hendrie: There's no in-between point.
Everett: No, no judgment allowed.
Oral History of Robert Everett
Hendrie: Exactly. Oh, that is funny. Now, was SAGE capable of detecting low-flying incoming planes?
That would've seemed to have been one of the hardest problems. Just because of the radar, not because
of the computers or anything.
Everett: The curvature of the earth.
Hendrie: Yes, the curvature of the earth.
Everett: The idea, in fact the original idea for SAGE, was to have small radars and multiple
close enough together so that they can see small airplanes at low altitudes. And this changed to big
radars with gap-fillers in-between. And the Cape Cod System had gap-fillers. And they were brought in
and used, but it was still a very difficult thing to do. Once the airplanes got in, and presumably within the
cover of these smaller sets, they could be detected. And then you'd have to carry it along through those
until they got close enough to a big set to be seen. Two things were done. One is, there were ships
anchored out…
Hendrie: Picket ships.
Everett: Picket ships. Because the worry was: if the airplanes had got in through the outer reaches of
the…
Hendrie: The system.
Everett: …the system. Then it was a serious matter anyway. So, you wanted to detect them far enough
out so you could do something about them. So they put ships out there, and they also had Texas Towers,
which were essentially drilling platforms with radars on them, which were put out. And then later there
were aircraft, radar aircraft, and an early version of the AWACS [Airborne Warning and Control System]
plane. And those, we built equipment for putting in them and transmitting the data back to the ground. And
those can fly up and down to give it a proper alerting, because they were expensive to keep all the time.
So there were these various attempts. What would have happened if the Russians had really attacked us?
I don't know. Certainly some of them would have gotten in.
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