Why wouldn't it be able to detect it from several kilometres ? Any "stealth" plane can be detected within 10-20km range by a modern radar.
I know. But this was the original statement by the IAF head BS Dhanoa when he claimed that the J-20 isn’t stealth because the MKI could detect it from “kilometers away”. At the time we just thought that it was an ignorant statement to make by a high level Air Force official because you should be able to track a 20 meter long object from several kilometers away with something called “eyeballs”.