When the target is above the the SNR, than several functions could return 0, so this issue should be investigated more.
I believe that when target goes out of P-40's detection, "Pat Hand" just must stop trackin it (when no range or angle track was established0, and when it appears again, should be reaquired with the joystick on p-40 and then send to "Pat hand'....
It is a quite an interesting issue how "Long track" is autotracking targets...