You use the helmet-mounted sight for attacking a visible airborne target in a dogfight. This Helmet-Mounted Target Designation (HMTD) system NSTs-27 frees the pilot from having to boresight his enemy by slaving the radar or the EOS (or even the missile seeker) to the helmet- mounted sight. The Helmet Mode (also called the Track View) lets you to keep your eye on the target at all times by turning your head in the direction of the target’s motion. The real system works by using a pair of head position sensors on the panel, on each side of the HUD. The radar (the EOS) locks onto the target in an area limited by the scan cone, which angular dimensions in Helmet Mode are about 3°x3°. The pilot should keep the cone in the limits of the radar (EOS) field of search. That means that you cannot use your helmet-mounted sight to acquire and lock onto targets beyond the gimbal limits of the radar antenna, the IRST sensor ball or missile seeker (whichever system is slaved at the time).
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altitude helmet mounted targeting circle weapon quantity weapon type airspeed
max scale range
HUD Mode Indicator
range to the target cannot be measured, the position of the target marker will be shown approximately. Here, you do not have information about type of target and the parameters of the target’s motion (see the figure below).
Typical HUD symbology for autotracking with the EOS
The HUD will also display the ‘GH’ Shoot Cue or ‘ JND’ (pronounced 'o-te-ve', stands for 'TURN AWAY' in Russian) Reject Cue. The Shoot Cue informs you that the selected missile is ready for launching and the target is within the missile's reliable launch parameters. Fire the missile by pulling the trigger ( Spacebar). The Reject Cue warns that you are too close to the target and prohibits launch. If you lock onto friendly aircraft, the IFF (Identification Friend or Foe) Cue at the left of the HUD will show ‘C’ (stands for the Russian word ‘Cdjq ’ and denotes 'Ours').
If the radar or the EOS switches to autotracking from Helmet Mode, cross-hairs superimpose on the Targeting Circle (see the figure below). When the HUD gets the Shoot Cue, the Targeting Circle flashes at a frequency of 2 Hz. If the onboard computer does not get target range information, the Targeting Circle flashes with a frequency of 1 Hz (this is typical when using the EOS).
Su-27 FLANKER
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Autotrack Mode
After locking onto a target in BVR, CAC or Helmet Mode, the radar (EOS) switches to Autotrack Mode that lets you automatically track a single target. In this mode the radar antenna (or the optic sensor ball of the EOS) is steadily directed to the locked target.
Radar tracking area for a single target is about 120°x120° in elevation and in azimuth, and tracking range for a medium -size target is from 55 km (rear hemisphere) to 100 km (forward hemisphere). When operating in Autotrack Mode, the radar provides target designation for guided missiles and illuminates targets for missiles fitted with SARH seekers.
If you use the EOS, the tracking area coincides with its field of search and equals 75° in elevation (15° down, 60° up) and 120° in azimuth. Tracking range depends on the type of target and the attack hemisphere. The EOS measures distances to the target for ranges from 0.2 to 3 km, with an accuracy of 10 meters. When operating in Autotrack Mode, the EOS provides target designation for guided missiles fitted with an IR seeker head.
After the radar (EOS) has locked onto the target, the HUD shows the following information: the ‘A’ Autotrack Cue, the range scale with the minimum and maximum launch range marks, the range to target mark (radar only), and the target aspect angle arrow. The HUD also displays the Aiming Reticle, altitudes and true airspeeds of your aircraft and of the target, the aircraft datum and bank scale, current combat mode, type of missile, quantity of the missiles, and missile flight time. The target's position is shown on the HUD as a point (the Target Marker) in angular coordinates scaled to the dimensions of the tracking area (see the figure below).
Typical HUD symbology for autotracking with the radar
Green lights on the Weapon Readiness Panel indicate that the missiles are ready for launch. The MFD works in track mode displaying information about the target. When you are tracking the target using the radar, target information may disappear for some time if the target deploys ECM or decoy countermeasures.
When you use the EOS, the HUD shows range, aspect angle, true airspeed and altitude of the target, and missile flight time only if the rangefinder can measure range (less than 3 km). If the
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target altitude your altitude Aiming Reticle pitch angle Target Marker missile flight time missile type target airspeed your airspeed range to target Autotrack Cue Radar Cue IFFCue aspect indicator shoot cue Target Marker EOSCue max range mark min range mark
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Aiming Reticle Targeting Circle
Step 2. Select a target
Once you have visually spotted a target, place it within the Aiming Reticle by maneuvering your aircraft.
Step 3. Lock onto the target
Enter targeting data into the seeker head by pressing the Tab key. If the locking conditions are met, the seeker locks onto the target and starts tracking it. We'll describe the Seeker Track Mode in a separate section below.