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402D: Navigation Systems
Terms in this set (64)
What are the operating principles of Ideal Navigation Systems?
Global Coverage, Self-contained, Passive operation, Immune to countermeasures, Useless to enemy, and Accurate & reliable
Ideal Navigation Systems:
Global coverage= positions the aircraft accurately any place in the world
Self-contained = No reliance on ground transmissions
Passive Operation = no transmitted signal
Immune to countermeasures = Cannot be jammed by hostile forces
Useless to enemy = Navigational aid not obtainable by hostile forces
Accurate and reliable = Steers the aircraft accurately and reliably, any place in the world
What are the types of Navigation?
Visual, Dead Reckoning (Deduced Reckoning), Celestial, Radio, Radar, Inertial
What type of navigation is earliest and most simple method and relies on observation of landmarks?
What type of navigation is solely by means of computations based on time, airspeed, distance, and direction? It also uses good visibility, a map, and a compass to get to a destination, but is not very accurate?
Uses stars as reference points
(i.e.)- Sextant = a navigation instrument that is used to establish position by measuring the height of stars from the horizon. You can use this even during the day and not just at night.
What type of navigation utilizes radio beacons (i.e. VHF omnidirectional range (VOR) and Tactical Air Navigation (TACAN))?
Navigation using radar frequencies (i.e. Rendezvous Beacon, Radar Altimeter (Ground Mapping))
Uses gyroscopic principles to sense movement of aircraft
What is Heading?
Angle formed between a reference and longitudinal aircraft axis
The direction in which the nose of the aircraft points
What is Course?
The direction in which the aircraft is moving
The line along the earth's surface over which an aircraft proceeds
What is Bearing?
The direction expressed as a horizontal angle normally measured clockwise from the forward point of the longitudinal axis of an aircraft to an object
What are the Action Points?
Defines total mission through series of reference points
Fix Point (FP)
Initial Point (IP)
Offset Aim Point (OAP)
Exit Point (EP)
ALCM Launch Point (ALCM)
What is Fix Point (FP)?
Used to update navigation system to present position of aircraft
The point in a mission where an operation will occur or begin
(i.e. a well defined point used as a meeting point with a tanker or starting point for bomb run)
Points which we plan to destroy
Offset Aim Points (OAP)
Used for targeting weapons when target is obscured from radar
Exit Point (EP)
Point in a mission where an operation will be completed
Point where aircraft will fly to, but not bomb
Air Launch Cruise Missile Launch Point (ALCM)
Point where crew or computer will launch missiles
What components are associated with each Action Points?
Latitude, Longitude, Elevation, Sequence Number
What are the components of Radio Navigation?
Similar to those found in radio communication systems
What is a device for finding the direction to a radio source and impacted by electrical disturbances?
Automatic Direction Finding (ADF)
VHF Omni-directional Range (VOR)
Short-range radio navigation system
Operates in the VHF range is Line-of-Sight (LOS)
VOR station transmits a navigation signal from a fixed ground station
(i.e. 150 mile radius)
(New Signal)<----150------>(Old Signal)
What allows the airborne receiving equipment to determine bearing and distance (slant range) from the ground station to the aircraft and allows point-to-point navigation via VOR ground stations?
VHF Omni-directional Range (VOR)
Tactical Air Navigation (TACAN)
Operates in UHF frequency range and is Line-of-Sight (LOS)
Is mobile and provides bearing and distance (slant-range) to a ground or airborne station
What is TACAN used for?
Close air support of ground troops
Determining position of aircraft
All military aircraft have some form of a TACAN system
Distance Measuring Equipment (DME)
Used in conjunction with both VOR and TACAN
Designed to give the pilot slant range distance to a point or, on the ground
Slant range is the line-of-sight distance between two points which are not at the same level (Altitude)
What is Slant Range?
It's the hypotenuse of a triangle.
Slant range = the line-of-sight distance between two points which are not at the same level (Altitude)
What is the purpose of Landing Systems?
Provide safe landing during inclement weather and poor visibility
What type of landing system includes the following signals: localizer, glide slope, and marker beacons?
Instrument Landing System
What is the localizer?
Indicates whether the aircraft is left or right of the runway centerline
What is the Glide Slope?
Indicates whether the aircraft is above, on, or below the glide path
What are marker beacons in Instrument Landing Systems?
Marker Beacons use visual and audio indications
Indicates distance to the end of the runway at specified points.
Outer = 4-7 miles
Middle = 3500 feet
Inner = 1000 feet
What are the drawbacks to Instrument Landing System (ILS)?
-Expensive to install
-Ground clutter (worse near cities)
-Narrow beam/fixed approach
-Only 40 channels available
What is the Microwave Landing System (MLS)?
Similar to ILS
-Uses a microwave signal not VHF radio signals
-Lower cost to install
-Flexibility = greater beam coverage to allow variable approaches
-200 channels provide less interference from ground clutter
The configuration of MLS is similar to ILS, how so?
Azimuth - indicates whether the aircraft is left or right of the runway
Elevation - indicates whether the aircraft is above, on, or below the glide path
DME/Precision (DME/P)- indicates distance to the end of the runway at specified points through visual and audio indication
Essentially, same functions as Localizer, Glide Slope and marker beacons but different names
Global Positioning System (GPS)
A satellite-based radio navigation system
Broadcasts a signal that is used by receivers to determine precise position anywhere in the world
What are Automatic Navigation Systems?
They automate the process of guiding and controlling aircraft
-Autopilot relieves the pilot from manually manipulating flight controls
-Aircrew monitor systems to ensure that autopilot performs intended functions
-Ensures aircraft remains within acceptable parameters of altitudes, airspeeds, and airspace limits
What is the Global Positioning System (GPS) and its functions?
Space-based, extremely accurate, three-dimensional location (latitude, longitude, and altitude), and velocity information (speed and direction)
Provides worldwide location and precise time information in passive all-weather operations
GPS made up of three parts: satellites orbiting the Earth; control and monitoring stations on Earth; and the GPS receivers
What are the common components of the Global Positioning System (GPS)?
What are the operating principles of the GPS?
Triangulation from 3 satellites
Military uses a minimum of 4 satellites to improve accuracy
GPS receiver triangulates by timing the travel time of radio signals
Makes corrections to signal delays using monitor stations
Inertial Navigation System (INS)
Can navigate from Point A to point B as long as it has an exact starting point
System senses aircraft pitch, roll, and acceleration
No theoretical limits to accuracy
What are the other functions of the INS (Inertial Navigation System)?
Works on principle of inertia
Relies on no external signals
Cannot be jammed
What are the components of the Inertial Navigation System (INS)?
Display Unit, Inertial Reference Unit (IRU), Accelerometers, Ring Laser Gyroscope, Alignment Gyros, Computer, INS battery
What is the Display Unit in the Inertial Navigation System?
Aircrew enters local latitude and longitude and 'fix-points' periodically to ensure accuracy of the system
What is the Inertial Reference Unit (IRU)?
Measure forces in any direction in space
What are Accelerometers?
What are Ring Laser Gyroscopes?
Calculates difference in time that two beams, travel around a closed path, traveling in opposite directions
Uses Doppler effect to judge subtle changes in length of the laser beams
Three gyros are used to sense changes in pitch, roll, and yaw
What are Alignment Gyros?
Sets an exact starting point
What does the computer do in the INS?
Processes data from accelerometers/performs required calculations
What is the INS battery?
30-minute backup power and is a time changed item!
What is the Astro-Inertial Navigation System? (AINS)
Subsystem on the B-2 aircraft
Computerized celestial navigation using stellar references
Can be used to update INS
What is Ground Proximity Warning System (GPWS)?
Compares the airplane's position in three-dimensional space to the terrain around and below, the aircraft
The Ground Proximity Warning System (GPWS) provides aural tone warnings for:
Excessive descent rate (Mode 1)
Excessive terrain closure rate (Mode 2)
Altitude loss after takeoff or go around (Mode 3)
Unsafe configuration (Mode 4)
Below Glide Slope Deviation (Mode 5)
The Enhanced Ground Proximity Warning System includes two additional features, what are they?
-Enhanced Forward Looking Terrain Avoidance and Premature Decent Alerts
What is the Traffic Alert and Collision Avoidance System (TCAS)II and what does it do?
-Computes distance, bearing, altitude, and closure rates relative to own aircraft
-TCAS interrogates Mode C or S of other aircraft transponders
-Generates aural and visual warnings when distance and closure rate becomes critical
What depicts aircraft on one more more instrument panel displays?
What is the Offensive Avionics Systems (OAS)?
Provides accurate data for Global Navigation and Weapons release
Provides bombing solution for "dumb" bomb jettison
What is the OAS Software?
Mission data tape contain coordinates
Latitude, longitude, and Offset Aim Points of assigned targets
How does the Offensive Avionics Systems (OAS) solve horizontal Bombing Problem?
Calculates direction or heading of the aircraft to get bombs on target
Calculates ballistic characteristics- how the weapon flies
How does the OAS solve vertical bombing problem?
Altitude must be calculated
Timing must be calculated
Offensive Avionics Systems (OAS)
Proper position of the aircraft is essential for desired placement over target area
Navigation System Malfunctions
Critical for mission success (i.e. navigation, munitions delivery)
Safety of flight
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