VHF Omnidirectional Range (VOR) Ground station oriented to magnetic north, transmitting directional information to aircraft Benefits More accurate, precise flying Reliable Not susceptible to interference Voice Capable Errors/Negatives Costly to maintain Line-of-sight

VOR Omnidirectional reference signal Directional signal from antenna rotating @ 1800 rpm Receiver uses phase discrimination Navigation in polar coordinates (rho-theta) Distance Measuring Equipment (DME) & often Tacan are colocated with VOR

VOR Capabilities VHF – 108.0-117.95mhz 1 LOP at a time Line of sight 1 LOP at a time 2 receivers give 2 LOPs (fix) VOR + DME = LOP & Arc (fix) Not sensitive to aircraft heading Fly to or from a VOR or intercept a radial Radial – courses oriented FROM the station

VOR Types High Low Terminal 1,000 – 14,500; 40NM * All altitudes AGL

VOR Types

The Principle of the VOR 360 Magnetic North 045 315 135º 270 090 Didn’t Touch 135 225 180 VOR receiver gives 1 LOP called a Radial

Parts of a VOR system Receiver Course Deviation Indicator (CDI) To/From ind. CDI – needle that moves across the face of the instrument to indicate aircraft position. Each dot is 2 degrees. OBS – allows pilot to select desired course/radial to fly - must align with DG, otherwise reverse sensing Ambiguity Indicator – indicates if selected course will take aircraft to or from the station - station passage - cone of confusion Omni bearing selector

VHF Omnirange

VHF Omnirange Which radial?

VHF Omnirange Show the interception

Flying the VOR Initial Tracking Tune, Identify, Twist Turn OBS to center needle and figure out position (use FROM) Note heading on top of card If flying FROM station (radial), then turn to that heading If flying TO station, put reciprocal heading on top and center, then turn to that heading

Flying the VOR Wind Correction Further away, more correction is needed to get back on track At 60NM from station, 1° = 1NM Generally, when within 20NM, 20-30° in direction of needle works Once needle centers, turn back towards original heading, but add wind correction of 5°

Flying the VOR Station Passage Switching Radials CDI will become very sensitive, and then begin to oscillate Flag will switch from TO/OFF/FROM Switching Radials During station passage, turn OBS to new course to fly

Flying the VOR Intercepting If needle is alive, then turn towards it as if you were tracking it If full deflection, first center needle to find what radial you are on Twist OBS back to desired course Parallel that course Turn 30-60 in direction of needle, depending on distance from station Once needle is alive, turn back in direction of desired course Follow tracking procedures

Distance Measuring Equipment (DME) Radio signal sent out from aircraft to ground station. Ground station interprets this signal and sends back. Equipment in aircraft measures time and converts to nautical miles. Errors Diagonal (slant-line) distance from station to aircraft – not lateral Becomes greater the closer you get to the station Greatest when directly over station at high altitudes Limited number of queries Uses Intersections/Fixes IAP Groundspeed

Types of Navigation Systems Pilotage Dead Reckoning Radio Navigation ADF VOR/DME/RNAV Electronic Navigation Loran GPS Inertial Celestial Types of Navigation: -Electronic Navigation: The evolution of radionavigation to include satellite based systems such as SATNAV and GPS.

Area Navigation (RNAV) Generic name for a system that permits point-to-point flight Onboard computer that computes a position, track, and groundspeed VOR/DME Loran GPS Inertial

LOng RAnge Navigation (LORAN) Collection of antennas throughout the United States transmit signals Aircraft receiver calculates position based on intersection of multiple signals

Global Positioning System (GPS) GPS = Global Positioning System A space based, all-weather, jam resistant, continuous operation, worldwide radio navigation system. Provides extremely accurate 3D location data as well as velocity and time. Doesn’t this sound pretty neat, holy grail of navigation Jam resistant, tell story about Iraqi GPS jammers and our GPS guided bombs

GPS System of 24 satellites, 4/5 of which are in view at all times Receiver uses 4 of these to determine position of aircraft Each satellite transmits code, which contains satellite position and GPS time Receiver, knowing how fast signal was sent and at what time, calculates position

GPS Glossary RAIM – Receiver Autonomous Integrity Monitoring Determines if satellites are providing correct data WAAS – Wide Area Augmentation System Collection of ground receivers take satellite data and correct it for atmospheric conditions Works based on known position of ground stations LAAS – Local Area Augmentation System Same as WAAS, but on a smaller, more precise scale For terminal area around airport

12,000 miles above Period = 12 hours

LOP – 1 Sphere Single range can lie anywhere on a sphere R1 Courtesy of Leica Geosystems

LOP – 2 Spheres Two ranges will intersect on a line, defined by the intersection of two spheres Courtesy of Leica Geosystems

LOP – 3 Spheres Three spheres intersect at a point Three ranges needed to resolve lat/long/altitude Notice that we said you need 4 before. The 4th is required to synchronize the receiver's clock Courtesy of Leica Geosystems

GPS Uses Civilian Uses Marine Navigation Air Navigation Surveying Search and Rescue Collision avoidance Agriculture Military Uses Marine Navigation Air Navigation Rendezvous Close Air Support Mine Warfare Unmanned Aerial Vehicles (UAVs)

Inertial Navigation System Dead-Reckoning Self-contained source of: Position, groundspeed, & heading Does not even need a receiver Cannot be jammed Gets better with use Applies a calibration correction after each flight

Primitive Accelerometer No Acceleration Acceleration M X Acceleration from the right F = kx = ma a = kx/m

Inertial Navigation Principles Acceleration is vectorially summed in x, y, & z. Output is compensated movement of the platform & for curvature & rotation of the earth.

Inertial Navigation Systems Early systems required precise mechanical parts Bigger is more accurate Modern systems can be: Mechanical (platform) Simple gyros Accurate Electronic (strapdown) Few moving parts Smaller Cheaper

Inertial Navigation Systems Aircraft systems use Pendulum accelerometers or MEMS Micro-electromechanical sensors Ring laser gyros To measure angular change INS complements GPS Mechanical Ring Laser Gyro

Types of Navigation Systems Pilotage Dead Reckoning Radio Navigation ADF VOR/DME/RNAV Electronic Navigation Loran GPS Inertial Celestial Types of Navigation: -Celestial Navigation: utilizes the known positions of celestial bodies (stars, planets, the sun and moon) relative to the earth to ascertain ship's position. Initially very mathematically intensive (3-D spherical trigonometry required) but it has now been reduced to tabulated information which is compared to actual observations to determine position.

Celestial Navigation Advantages No power required Self contained Cannot be jammed Available everywhere Disadvantages Dusk & dawn only Clear weather only Slow for aircraft Needs the art of nav. Navigator’s skill Requires computation At least data entry Not on test at all

Circle of Equal Altitude Charles Lindbergh used this during the night Circle of Equal Altitude DeRemer & McLean Global Navigation

Types of Errors Error increases with distance VOR/DME, ADF Error increases with time DR, Inertial Reliability Concerns GPS, Loran, Celestial Human error Wise Old Owl

Which Types of Navigation are Important to a Student Pilot? Pilotage Dead Reckoning Radio Navigation ADF VOR/DME/RNAV Celestial Electronic Navigation Loran GPS Inertial

If Something Seems Wrong, it Probably is! Be suspicious. Check and recheck. If you cannot tell your passengers your ETA at the destination, you are not navigating. Navigation Philosophy

What can you do if you’re lost? Assume you’re near your DR position Do not assume a huge wind just came up Use your VOR/DME or 2 VORs Look on the chart for landmarks Especially those that are shown small If you miss a checkpoint, hold your heading & look for the next one Do not guess where you are! If all else fails, CALL ATC (after all, YOU are paying for it) Show what happens when you circle – get lost 2 VORs give you a fix