I'd been wondering how the SA-11 operators initially acquired the plane with such a narrow beamed radar.
The beam coverage in the vertical is only 6 or 7 degrees but, for comparison, the widest air-to-air beam on US F-16s is only 6 degrees, with pilot controls to narrow that to 4 or 2 degrees for better target separation and more rapid position updates.
The rest is up to a poor man's C&C - they have somebody at the end of the runway who texts an order for one pizza, extra tomato sauce, for pickup at some time. Once you know what airbase, how many planes, what type, you start scanning the appropriate 120 degree field repeatedly, adjusting the antenna angle so you build an overlapping picture that covers the possible altitudes. If you get the expected number of returns at about the predicted flight time, you lock one up and shoot. If you don't fully understand the system, get too excited, or are bad with geometry and algebra, you can read the altitude and closure rate wrong, not notice the target return is a bit too strong (or mistake that for lower and closer), etc.
Even if you know what you are doing, since the TELAR has to emit to locate the target and then provide illumination for the duration of the engagement, you might be in a hurry as the other side, once they notice your side can reach planes above MANPAD altitudes, may have anti-radiation missiles that can kill you. One of the nice features of an integrated air defense system is that missile launchers and radar emitters don't have to be collocated or even locally manned, making the job of sorting targets less pressured.