HEADS UP DISPLAY

DESCRIPTION - HEAD UP DISPLAY SUB-SYSTEM

The HUD visually presents required symbology for flight and weapons firing on a partially reflective beam splitter and superimposed on real world image. The primary use of the HUD is for aiming the helicopter to fire rockets and to provide the pilot steering indications for meeting the helicopter constraints in operation of the TOW missile system. The secondary use of the HUD is for the display of the engine torque, radar altitude, magnetic heading, and range for flight safety purposes when the pilot is flying head up with eyes focused outside the cockpit. The components of the HUD are the head up display, signal processor, and HUD boresightable mount.
ITEM FUNCTION
PWR Switch  
ON Electrical power applied, symbols displayed depend on MODE switch position.
STBY Electrical power applied, no symbols displayed.
OFF All electrical power removed from HUD circuits.
MODE Switch  
NORM Displays basic symbols according to firing mode selected.
TEST Displays all heads up display symbols except the stadiametric reticle.
STAD Displays stadiametric reticle which is a backup reticle.
RKT Switch  
IND Displays a continually computed rocket release  point.
DIR Displays a continuously computed rocket impact  point.
AUTO BRT Switch  
ON Allows brightness of displayed symbols to be automatically adjusted.
OFF Disables automatic brightness control feature.
  CAUTION

Do not leave in night filter position in sunlight. Sunlight will damage the night filter beyond repair.
NIGHT FILTER control knob Selects usage of night filter by rotating the knob.
HUD BRIGHTNESS control knob Controls brightness of heads up display element when rotated as shown by BRIGHT arrow.

----------HEADS UP DISPLAY ( HUD ) SYMBOLS----------

SYMBOL FUNCTION
Missile Select Indicates TOW missile selected for firing from left or right launcher.
TOW Prelaunch Constraint Represents boundary within which the pilot must keep the gunner LOS and target prior to and during TOW missile launch.
TOW Postlaunch Constraint Represents boundary within which the pilot must keep the gunner LOS after TOW missile launch and until wire cut or missile impact.
Ascend-Descend
ON - Indicates nose of helicopter must be raised or lowered to meet prelaunch constraints.
OFF - Indicates helicopter attitude and line-of-sight rate are compatible.
Torque Indicates engine torque in percent.
Source and Range
Displays range in meters and source of range :
F - Range from fire control computer ( FCC ).
L - Range from laser ( displayed when FCC fails ).
Heading Displays magnetic heading of helicopter.
Radar Altitude Displays altitude above ground level in five feet increments. When absolute altitude exceeds 1495 feet, the numbers will blank and will not unblank until the altitude drops below 1475 feet.
Upper Limit
Lower Limit
Illuminates when within 25 feet of present upper or lower altitude limits selected on AN/APN-209 radar altimeter.
Boresight Reference Used for boresighting weapons and serves as aircraft datum line (ADL) reference symbol during flight. It is used during indirect firing of rockets.
Gunner LOS Displays line of sight as commanded by telescopic sight unit (TSU).
Beyond Field of View Caution An X superimposed on gunner LOS to indicate LOS has exceeded field of view limits.
Fire Control Reticle Indicates target area for rocketing firing.
LA Superimposes on fire control reticle and indicates FCC has failed and raw laser range is being used.
LOS Coarse Azimuth Pointer Indicates azimuth reading of gunner TSU LOS.
Stadiametric Reticle Displays when HUD MODE switch is in STAD position and is used as a back up reticle.

 

Return to The Cockpit ( Pilots Station )
Return to Attack Helicopter Home Page