Navy Advancement Career Guide & NPC News

203 Avionics Systems

203.1.1 State the purpose of the following communication systems:

a. Very-High Frequency/Ultra-High Frequency (VHF/UHF)-The VHF/UHF communication system provides air-to-air and air-to-ground plain or secure communications in fixed frequency mode, anti-jam (ECCM) mode, or maritime mode. The system operates on 20 preset channels (fixed frequency mode or anti-jam mode) guard (G) channel, manual (M) channel, cue (C) channel, and 55 maritime (S) channels, within the range of 30 to 399.975 MHz.

b. Intercommunication and Audio System (IAS)- Provides amplification and routing of audio signals between cockpit, ground crew, and rear cockpit. It also provides supplemental and backup Communication, radio navigation, and identification (CNI) controls, combined aircraft threat warnings and advisories, weapon tones, and voice alerting.

203.1.2 State the purpose of the following navigation systems:

a. Tactical Air Navigation (TACAN)-Used to determine the relative bearing and slant range distance to a TACAN ground station or a similar TACAN equipped aircraft. The TACAN is also used as a source to keep aircraft present position and update the aircraft present position being kept by another source (INS or ADC)

b. Inertial Navigation System (INS)-A self-contained, fully automatic dead reckoning navigation system. On 164945 and up A/C the INS is closely coupled by the mission computer with the global positioning system (GPS) to provide highly accurate aircraft present position and velocity data. The Ins detects aircraft motion (acceleration and attitude) and provides acceleration, velocity, present position, pitch, roll, and true heading to related systems.

c. Global Positioning System (GPS)-A space based, radio navigation system that provides continuous, all weather, passive operation to an unlimited number of users anywhere on the earth.

d. Attitude Reference Indicator (ARI)-A self-contained attitude reference system which provides backup pitch and roll attitude for use by other systems.

e. Instrument Landing System (ILS)-An all weather approach guidance system. The ILS decodes transmitted azimuth and elevation signals during an aircraft approach and provides steering information to be displayed on the head-up display (HUD), the attitude reference indicator or the electronic ADI indicator display. The ILS can be activated by three modes of operation. Primary mode, which uses the upfront control (UFC), the backup mode which uses the intercommunication panel, and the automatic carrier landing (ACL) mode which uses the mission computer system to control the ILS when the data link system is in ACL mode.

203.1.3 State the purpose of the following tactical mission systems:

a. Identification Friend or Foe (IFF)-Provides automatic identification function for the aircraft. The system receives challenging signals and determines the correct code and mode of challenge, and automatically transmits a coded reply. The system operates in modes 1,2, and 3a, which are selective identification feature (SIF) modes and in mode C, altitude reporting mode. Mode 4 which is a crypto mode, is available when the mode 4 computer is installed.

b. Data Link-Provides a communications link between the aircraft and controlling tactical data system.

c. Forward Looking Infrared (FLIR)-Provides thermal imagery, in television format, for detection and identification of tactical targets. It is able to automatically track selected targets and provide accurate target line-of-sight pointing angles and rates to the mission computer system.

d. Radio Detection and Ranging (RADAR)-Provides Air-to-air (A/A) and Air-to-ground (A/G) modes for target detection, designation, tracking and navigation. Also provides terrain avoidance for low level navigation, a detection and tracking capability for moving surface targets, and precision velocity measurement for navigation update and improved weapon delivery accuracy.

e. Mission Computer (MC)- 1) Computes and controls the data sent to the MPCD group. 2) Computes and produces missile launch and weapon release commands. 3) Provides mode control and option select for various avionics systems. 4) Provides mode control and option select data from the MPCD group to avionics systems for control and computation. 5) Outputs built-in test (BIT) initiate signals to various avionics systems and monitors BIT status.

f. Laser Detector Tracker (LDT)-Detects and automatically tracks coded laser energy reflected from illuminated ground targets. The LDT system is used to deliver laser guided weapons.

203.1.4 State the purpose of the following Tactical Electronic Warfare Systems (TEWS):

a. Interference blanker-Interfaces onboard RF transmitters and receivers that share common parts of the radio frequency spectrum.

b. Countermeasure set (ALQ-126)-Detects and deceives enemy pulse fire control and guidance radars. When threat signals are received, the countermeasures set detects, processes and transmits deception signals.

c. Countermeasures warning and control-Provides aural and visual alerts upon detection of threat radar signals and at the same time provide information to the HARM missile and countermeasures set.

203.1.5 Describe the following Multipurpose Display Group (MDG) components:

a. Heads-Up Display (HUD)-The primary flight instrument in the aircraft. It provides flight, navigational steering, and weapon delivery information. The combiner assembly reflects the symbology into the pilot's forward field of view.

b. Digital Display Indicators (DDI)-LDDI-used primarily for stores management, caution, advisory, and BIT displays. RDDI-used primarily for sensor displays. Information can be brought up on either DDI and both are interchangeable.

c. Horizontal Indicator (HI) (BUNO 161353 thru 163782)-Used primarily to provide aircraft attitude, steering, and navigation information with a projected moving map superimposed over the CRT display.

d. Multipurpose Color Display (MPCD) (BUNO 163985 and up)-Provides following displays, aircraft attitude, navigation, A/A, A/G, warnings, cautions, and advisories, and various aircraft checklists.

203.1.6 Describe the function of the Digital Map Set (DMS)-Provides the following:

a. Moving map image, continuously updated for tactical and navigational situations.

b. Alphanumeric and graphic symbology for tactical and navigational situations. The symbology can be displayed overlaying the moving map or by itself.

c. Up to 100 data frames for display. The data frames contain information such as check list and emergency procedures.

203.1.7 State the location, purpose, and color of the following exterior lights:

a. Position- A white light just below the tip of the vertical tail fin. (Vertical Stab.). Three green lights on the right side of the A/C and three red lights on the left side of the A/C. The green and red lights are located at the following locations. Wing Tip, Lex Forward of the Wing Root, Aileron hinge.

b. Strobe-Two red (anti-collision) lights, one on each outboard vertical stab.

c. Landing/taxi-White light on the nose gear strut.

d. Approach-Green, Amber, Red lights located on the nose gear strut. Function of angle of attack. Green indicates high angle of attack, Amber indicates optimum, and Red indicates low angle of attack. The operating light flashes if the arresting hook is not down when the hook bypass switch is in carrier.

e. Formation-8 lights green in color. 2 on each wing tip, one on the outside of each vertical stab., one below each vertical. stab. On the aft fuselage, one on each side of the forward fuselage just forward of the lex.

203.1.8 State the purpose of Flight Incident Recorder and Monitoring System (FIRAMS).

Monitors engine and airframe operational status for unit failures and caution/advisory conditions when the mission computer system is operating. If the mission computer system detects a unit failure, it commands the FIRAMS to store the applicable maintenance code. When the mission computer system detects specific unit failures, it commands the FIRAMS to store significant maintenance data and selected tactical information in a solid state memory device.

203.1.9 State the purpose of the Deployable Flight Incident Recorder Set (DIFRS).

The DFIRS has two functions; the storage of flight data and the deployment of this data. The DFIRS signal data recorder and DFIRS data transfer interface unit provide flight data storage. The DFIRS front mount, rear mount, underwater initiator, impact initiator, sever able door, thin layer explosive and shielded mild detonating cord provide recorder deployment. Thirty minutes of continuous flight data is stored. The impact initiator is activated when sufficient G loads exist. The underwater initiator is activated when the aircraft reaches a depth of 15 to 25 feet. When the recorder is deployed, the beacon transmits on the military UHF guard frequency of 243 MHz. The antenna is an integral part of the recorder and transmits signals in all directions. The battery supplies power to operate the beacon for at least 72 hours.

203.1.10 State the purpose of the following flight reference equipment:

a. Pitot Static system-Measures pitot and static pressures surrounding the aircraft.

b. Indicated airspeed indicator-Displays airspeed as a function of the pitot and static pressure. Airspeed is indicated in 10 knot increments from 20 to 200 knots and 50 knot increments from 200 to 850 knots.

c. Standby pressure altimeter-Uses static pressure and provides a pointer display for altitude to 1000 feet, a drum display for altitude 1000 feet to 50,000 feet and a four digit display for indicating barometric pressure.

d. Vertical speed indicator-Senses changes in static air pressure and displays them in the form of climb or dive rate from 0 to 6000 feet per minute.

203.1.11 Describe the function of the following Air Data Computer (ADC) system components:

a. ADC-Receives inputs from various aircraft sensors. Any errors in these inputs are corrected in the ADC. These corrected signals are used to compute accurate air data and magnetic heading. ADC outputs are used for primary flight data displays, navigation, weapons delivery, altitude reporting, environment control, and unsafe landing warning.

b. Airstream Direction Sensing Units (ADSU)-Provides angle of attack (AOA) information to the ADC and electronic flight control system. The ADSU measure the difference between the longitudinal axis of the aircraft and the local air stream surrounding the aircraft.

c. Angle of Attack (AOA) indexer-On the left side of the HUD. Shows approach angle of attack (AOA) with lighted symbols. The indexer operates only with the landing gear down and weight off the gear. Symbol lights to indicate approach speed red V (fast), amber circle (optimum), and green V (slow). The Lighted symbol will flash if the arresting hook is up and the HOOK BYPASS switch is in CARRIER.

d. Total Temperature Probe (TTP)-Measures total temperature of the air outside the aircraft. The TTP converts the temperature to an electrical signal and sends it to the ADC.

203.1.12 Describe the function of the following electrical power components:

a. Generator Converter Unit (GCU)-Protects against damage due to under voltage, over voltage, over and under frequency, and feeder faults. If a fault or malfunction occurs, the GCU removes the affected generator from its buses.

b. Transformer-Rectifier (TR)-Two in A/C. Transforms AC power from the generators into DC electrical power and supplies to the DC buses.

c. Utility Battery (U BATT)- Used for engine start when external power or aircraft generator power is not available, and are used to power the essential 24/28 volt dc bus when both transformer-rectifiers are lost. Powers the maintenance 24/28 volt dc bus when both transformer-rectifiers are inoperative. Allows operation of the canopy and maintenance monitor on the ground without any other electrical power on the aircraft.

d. Emergency Battery (E BATT)- Used for engine start when external power or aircraft generator power is not available, and are used to power the essential 24/28 volt dc bus when both transformer-rectifiers are lost. Contactor will automatically close in response to a low voltage condition from the U BATT.

203.1.13 Describe the function of the Automatic Flight Control System (AFCS)

Provides autopilot and automatic throttle control (ATC). Auto pilot provides commands to the electronic flight control system to maintain a constant heading, altitude, or attitude. ATC positions the engine throttle levers and power lever control to maintain a constant angle of attack during landing, with approach power compensation (APC), or constant airspeed during flight, with velocity control system (VCS).

203.1.14 State the purpose of the nose wheel well Digital Display Indicator (NDDI).

Receives and stores maintenance codes from the recorder, and provides a visual display of stored maintenance codes on operator request. Provides for manual activation of MSDRS to perform fluids level test of consumable fluids.