[barf]

I'll ask a simple question of a simple person. How did GCA work before secondary radar came into use? I was first associated with secondary radar back when it was classified secret. But GCA went back to before that. GCA used both the elevation angle and range to locate the plane. Are you going to tell me that GCA was only fiction because primary radar can not locate an object?

[Rokke]

"I'll ask a simple question of a simple person. How did GCA work before secondary radar came into use?"

Why thank you Barf. Here is your simple answer. GCA sites are actually composed of two radars. One tracks in a horizontal beam, the other in the vertical. The control actually has two presentations to look at to determine whether you are on course and glideslope, and he's not watching for altitude so much as monitoring deviation from a specific glideslope. GCA radars are focused on a relatively narrow azimuth, and are fairly high powered. This allows a rapid update rate.
Surveillance radars on the other hand, are typically composed of one large antenna that sweeps 360 degrees. Most ATC surveillance radars only look for range and azimuth and rely on transponders to assess altitude. If you are going to accuse me of lying about this, I suggest you call your local ATC facility and ask them.