I was flying a TE that featured some MiG-23MLDs. I saw the ^23 on the RWR, but I was at 200 feet, so I thought I was safe. From the ACMI, it's clear they were simply flying a stern-conversion on me and they ended up downing me with an IR missile. I didn't see any search radars on the RWR, so they must've been using their own radar to find me.

Is this realistic to have MiG-23's detecting us at 200 feet? I seem to remember hearing that MiG-23's can't see anything under 2000 feet, and 200 feet is challenging, even for today's modern fighters. Right?

Does anyone have some good links on what NOE profiles can defeat what systems? All the SAMs have minimum and maximum ranges and altitude available, but I can't find any information on fighters' look-down capabilities.

Edit: I am able to hide from J-5A's like this, so Falcon seems to model means-of-detection. The J-5A's just fly around looking for me and if I pop up or go radar/ecm active, they find me. I haven't tried older models of MiG-23s or any -21's, though. Still, I was under the impression that 200 feet would present difficulty for most if not all fighter aircraft.

That's a good question

There are also a ton of MiG-23 variants

A little of topic, but anyway: My girlfriend’s brother works in the Norwegian army, his job is to plan flight routs for jets and helos.
He was stationed in Kosovo some years ago and had this scaring experience.
“We were on a recon mission at night in a helo. Everything was ok but suddenly the RWR flashed and the alarm yelled.
The pilot instantly dived to the ground and desperately tried to break the lock by following the ground down a valley, but it was impossible. Our altitude was no more than 2/3 yards above the ground most of that time. Then it stopped and shaking like H*** we returned to base immediately and reported this.
It turned out that it was two F-15C that used us to “practice” on!” So at least the radars of the F-15 have no problem detecting and keeping lock on at target at extremely low altitude.

It's a look down - shoot down radar. You can't break a lock flying low, you need to get a mountain between yourself and the threat. Flying low will only work with SAM sites, because of the ground radar.

According to the wikipedia article aboult Mig-23's MLD variant: "Significant improvements were made in avionics and survivability: the Sapfir-23MLA-II featured improved modes for look-down/shoot-down and close-in fighting."

So, take care when 23's appear on your RWR screen, even if you are flying low.