Drawing: Cobra Drawing: Cobra

Head Up Display

Drawing: Head Up Display

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 All basic symbols displayed.
     TEST Displays all heads up display symbols.
     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.
     ON Allows brightness of displayed symbols to be automatically adjusted.
     OFF Disables automatic brightness control feature.
NIGHT FILTER Control Knob Selects usage of night filter by rotating knob.
Control Knob
Controls brightness of heads up display element when rotated as shown by BRIGHT arrow.


Symbol Description
Prelaunch Symbol TOW Prelaunch. Displayed in prelaunch mode only. Either left or right missile is displayed dependent upon missile selected. Vertical positioned rectangle is switched to horizontal position when fire control status has changed from TOW attack to TOW fire. Scale factor of area covered by rectangle to real world is 1:1 in azimuth and elevation.
postlaun.gif (248 bytes) TOW Postlaunch. Fixed horizontal rectangle displayed 1.5 seconds after TOW missile is fired. Scale factor of area covered by rectangle to real world is 23:1 in azimuth and elevation. TOW postlaunch window is removed from HUD display at wire cut.
uparrow.gif (127 bytes) Ascend. Displayed in lower left corner. Arrowhead pointing vertically up is a command, indicating nose of aircraft must be raised before firing TOW missile. Symbol extinguishes when required attitude is reached.
dwnarrow.gif (125 bytes) Descend. Displayed in lower left corner. Arrowhead pointing vertically down is a command indicating nose of aircraft must be lowered before firing TOW missile. Symbol extinguishes when required attitude is reached.
torrange.gif (310 bytes) Engine torque. Displayed in upper left corner. Display indicates percent of rated torque. One to three digit number followed by percent sign. Display ranges from 0 to 145.

Range. Displayed in upper right corner. 1 to 4 digit number. L indicates raw laser range input information. F indicates Fire Control Computer input information. Number changes in 10 meter increments; i.e., last number is always zero. Display ranges from 10 meters to 9.99km.
headalt.gif (357 bytes) Magnetic Heading. Heading of aircraft with respect to magnetic north. Displayed in lower left corner of HUD. Three digit number followed by degree sign. Display indicates from 0 to 359.

Altitude. Displayed in lower right corner, one to four digit number indicates in feet, in increments of 5 feet. Display is blanked above 1499 feet and reappears at 1475 feet.
uploalt.gif (202 bytes) Upper/Lower Radar Altitude. Arrowheads pointing at altitude numerics from above and below. Arrowheads appear when preset upper or lower altitude limits are reached. Input information from radar altimeter.
boresite.gif (302 bytes) Boresight Reference Symbol. Stationary and centered on ADL. Displayed in all modes except stadiametric mode.
gunlos.gif (195 bytes) Gunner's LOS cueing. Cross hairs, location of symbol on display indicates position TSU is pointing (looking) at. In normal modes, if gunner is looking outside the HUD field of view (FOV) limits, the LOS CUE symbol will be limited at edge of FOV and be overlayed by an X. In TOW mode, under these conditions, the X will flash at a 4 Hz rate.
caution.gif (332 bytes) Caution Symbol. When fire control reticle gunner's LOS cueing and/or coarse azimuth pointer symbol reach or exceed outer display limits, a Caution symbol superimposes each out-of-limit symbol. In TOW mode, the X will flash at 4 Hz rate whenever the TOW firing constraints are not met. Caution extinguishes when symbols are within limits.
azsymbol.gif (333 bytes) Azimuth (AZ) course scale and AZ course pointer. Pointer represents position of Telescopic Sight Unit (TSU) with respect to aircraft datum line (ADL). Displayed in all modes except STAD mode. Scale divisions are ±30°, ±60°, ±90°, ±110° measured from 0° scale center. Caution symbol superimposes pointer when it reaches ±110°. Scale is stationary, pointer moves in horizontal plane only.
stadret.gif (681 bytes) Stadiametric Reticle. Fixed Aiming Reticle for Rocket Fire. Used in event both the FCC and Laser have failed. This symbol is generated entirely within the HUD. Pilot will estimate range to target, and line up target with appropriate range marker on Stadiametric Reticle. (Each dot represents 1000 meters) Example: If estimated target range is 2000 meters, align aircraft such that the 2 dots just above center cross hairs overlay target. The positioning of dots are based on the ballistics equation for rockets. The tick marks are for additional range/angle reference, and are spaced specific number of mils apart.
dirrectl.gif (557 bytes) Direct Rocket Reticle. Used in Direct Rocket Mode. Reticle position on display is the Continuously Computed Impact Point (CCIP) of the weapon if the pilot were to fire at that instant. Moves in both X and Y direction. Tick marks are for range/angle estimation, in MIL spacing. Caution symbol is superimposed across reticle center when reticle reaches display FOV limits
fixretcl.gif (582 bytes) Fixed Gun Reticle. Used when firing fixed guns from wing pods. Reticle is in fixed position centered on the Armament Datum Line (ADL).
bakrectl.gif (626 bytes) Backup Direct Rocket Reticle. Used when Fire Control Computer (FCC) has failed. Positioned in elevation only as a function of raw laser range (LA).
indrectl.gif (526 bytes) Indirect Rocket Reticle. Displayed in Indirect Rocket mode only. Movable in X and Y direction. Represents a Continuously computed Release Point (CCRP), which is the point in space from which to launch weapon to hit target. Caution symbol is superimposed across reticle center when reticle reaches display FOV limits.

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Updated: 12 January 2008
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Born on 30 March 1999