Russian R-27 air-to-air missile (AA-10 Alamo) (military.cz)
The R-27E (Extended range series) introduced in service 1990 came in two variants the R-27RE (Alamo-C) Semi-Active Radar & R-27TE (Alamo-D) "with a more advanced version of the infrared finder, capable with helmet sight of pilot."
The R-27ET is distinguished of the two as the only one capable of interacting with the helmet sight. The R-27ER is not.
Neither is stated here:
Or here in detail:
Only IR missile targeting shows up on the sight rings in HMS. Not radar guided missiles. You must still point the nose at the target & allow it to be captured by the radar.
Regarding radar guided munitions :
If radar guided missiles are selected, Target designation in the in the HELMET mode will issue directive to the RLPK-29 radar sighting system & AFTER the target is caught by the radar sight (you must still point the nose at the target to achieve this) further aiming is carried out according to the HUD information. There is no HUD information unless you point the nose at the target.
You cannot use the HMS to shoot fake high off boresight radar missiles. All you can do is notify the radar to stand-by when radar missiles are selected & what direction the target will come from with the HMS (Opto-electronic pointing station). So that when the target does come into the radars field of view, it will immediately lock on to the target.
This is literally nothing more than an ACM mode in all fighters or a Range finder in the Kfir C.7
The radar is not swinging the dish every which way according to a pilot’s line of sight. The Radar is no longer off or in a search pattern but is standing-by for when the target enters its FoV. Only IR missile seekers follow the pilot’s line of sight. Literally stated in dude’s own source.