Ground lesson 16 (4) - Radio navigation

VOR navigation

• How they work
• Very high frequency omnidirectional range
• Sends out two different signals. One master and one secondary 
• Master signal is constant for each radial
• Secondary signal rotated about the station
• Receiver compares the two signals and can tell you where the selected radial is
• Limited to line of sight
  
  
• Station and radials
• 360º
• Radials are always from the station 
• Oriented to magnetic north
  
  
• VOR roughness
• Minor CDI roughness brief flag alarm if flying over mountainous terrain
  
  
• Standard service volumes

• HSI
• Combines vor and directional gyro
• Also gives you glide slope
  
  
• VOR navigation
• Station ID
• Find the morse code on sectional or low enroute chart
• Press ID button -> turn up volume -> listen to morse code
• During maintenance morse code removed or send out test signal ( _••••_ )
  
  
• Intercepting radial 
• Take the difference between the radial you are on and the radial you want to intercept 
• On radial 100 and want to intercept radial 120 -> 20º difference
• Radial difference * 2 ( not less than 20º and not more than 90º intercept angle)
  
  
• If flying to the station, always set course to reciprocal radial
• Turn into the course
  
  
• Tracking
• Follow the selected radial
• If the CDI goes to the left, turn to the left
• Remember to correct for wind drift
  
  
• Homing
• Continuously twist the obs knob to center the CDI
  
  
• Reverse sensing
• When the CDI indicates the reverse of normal operations
• This will happen to a basic VOR if you set it to the reciprocal of the intended course
  
  
• Station passage
• The CDI will be more sensitive the closer you get to the station 
• Eventually oscillations and/ or full scale deflection 
• Cone of confusion 
• Nav flag may also appear
  
  
• Station passage is complete with flag flip (to/from)
• 1 NM from VOR maintain heading
  
  

VOR Checks

• Has to be done every 30 days
• VOR - VOR test facility 
• Transmits a test signal which can be found in the A/fd
• Procedure
• Tune in frequency in vor receiver (A/FD)
• Center the CDI needle
• Should read 180º with a TO indications or 0º with FROM (think blink 182
• Maximum error is +/- 4º
  
  
• VOR receiver checkpoint
• Frequency and radial can be found in A/fd
• Procedure 
• Tune in frequency in VOR receiver
• Center CDI needle
• Should read radial specified in A/fd with a from indication
• Max error +/- 4º for ground check
• Maximum error +/- 6º for airborne check
  
  
• Dual VOR check
• Used for 2 VOR independent from each other 
• Maximum error is 4º between 2 receivers
  
  
• VOR records
• Each person making the check must enter the info in the aircraft or other records(91.171)
• “D.P.E.S” date, place, error, signature
  
  
• VOR, VOR DME, AND VORTAC
• VOR provides course information
• VOR.DME provides course and distance
• VORTAC is both VOR and tacan
• TACAN is used by military - provides course and distance
  

DME navigation

• Distance measuring equipment
• Works on line of site
• Aircraft has a DME transmitter that send out radio frequency pulses 
• A ground facility receives the signals and sends them back to the aircraft
• The airborne DME measures time between the signal and translates it into distance
  
  
• Reliable signal will be received up to 199 NM line of site 
• Slant range
• Distance is measured from your aircraft to the station, not ground distance
• The error is greater the higher you are and the closer you are to the station
  
  
  
• DME arc

• Usually a transition to the approach course 
• How to fly it
• Lead the turn into the ark by 0.5 NM
• Turn 90 
• Monitor your distance
• Turn 10º twist 10º → continuously center the CDI needle
  
  
• Frequency pairing plan

• You only have to put in the VOR frequency to receive the distance info
• This assumes that the station has DME info (VOR/DME, VORTAC, ILS/DME,LOC/DME)
  
  
• DME is identified by a morse code with a tone slightly higher than the VOR/LOC tone
• Heard once every 3 - 4 times the VOR/LOC

NDB navigation 

• Ground facility 
• Called NDB - non directional radio beacon
• Transmits radio energy in all directions 
• Frequencies 
• Not approved for IFR navigation but can be used for VFR
• ADF receivers do not have a "flag" to warn the pilot when erroneous bearing information is being displayed
• The pilot should continuously monitor the NDB's identification
  
  
  
  
• ADF - automatic direction finder 

• Equipment in the aircraft
• Always points to the antenna 
• Shows you the relative bearing from the aircraft's magnetic heading to the transmitting station
  
• RMI - radio magnetic indicator 
• ADF’s version of the HSI
• Combines and ADF with a heading indicator connected to a fluxgate
• MH + RB = MB

Area Navigation (RNAV)

• Basic of area navigation 
• Enables point to point navigation without the need of overflying a station 
• Airborne computer determines the aircraft position, actual track, and groundspeed
• Rnav equipment include VOR/DME  with airborne computer or GPS
• RNAV equipment must be approved for use under IFR
  
  
• VOR/DME RNAV

• Creates a waypoint by using an airborne computer
• Uses facility to make angles to calculate distances
  
  
  

RNP - Required navigation performance 

• Type of Performance-based Navigation that allows an aircraft to fly a specific path between two, 3 dimensionally defined points in space
• RNP is very similar to RNAV
• Only difference is on-board performance monitoring and alerting 
• Ensure that the aircraft stays within a specific containment area
• Must stay in defined space for 95% of the time
  
  
• Levels of RNP

• Distance from the centerline of the flight path that must be maintained (95%)
• Enroute - 2.0 nm
• Terminal - 1.0 nm
• Approach - 0.3 nm
  
  

GPS - global positioning system 

• Developed and operated by the DoD
• 31 satellites 
• 5 should be in view at all times
• 6 orbital planes, 4 in each
• 3 distinct functions 
• SPACE: all the satellites 
• CONTROL: ground based GPS monitoring and control station to ensure accuracy
• USER: receiver that calculates position, speed and distance
  
  
• How it works

• Satellite transmits a specific code
• Contains info about position, time, health, accuracy, etc
  
  
• Receiver calculates the time it took for the signal
• At least 4 satellites for 3D position 
• 4th used for accuracy since the satellites use atomic clocks, and receivers don't
  
  
  
  
  
• RAIM - receiver autonomous integrity monitoring 

• Integrity is often defined as the ability of the navigation system to provide timely warnings to the user when it is inadvisable to use the system for navigation
• Detects if the GPS is not accurate enough 
• Senses if the satellite is providing corrupt info 
• Needs at least 5 satellites in view for fault detection 
• RAIM fault detection algorithm 
• Fifth satellite is the one to monitor the other four
  
  
• Needs 6 satellites in view for fault exclusion
• RAIM exclusion algorithm
  
  
• If RAIM is lost
• We have a notification of ‘Loss of Integrity’ symbol that appears on our PFD
• On an approach, we must execute a missed approach immediately
• Passed our FAF, time period of up to 5 min to land before executing a MAP
• WAAS - wide area augmentation monitoring 

• System of satellites and ground stations that provide GPS signal corrections, giving better accuracy
• How it works
• Multiple ground reference stations positioned across the U.S. that monitor GPS satellite data
• 2 master stations, located on either coast, collect data from the reference stations and create a GPS correction message
• Correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere
• Corrected differential message is then broadcast through 1 of 2 geostationary satellites
• The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal
  
  
• WAAS accuracy → 10 feet/ GPS accuracy → 50 feet
• Allows you to fly gps approaches with vertical guidance 
• Also uses Fault Detection and Exclusion
  
  
• Regulatory requirements for ifr GPS navigation 
• Receiver must be IFR approved 
• Preflight: check GPS NOTAMS
• Database must be up to date (every 28 days)
• Aircraft must be equipped with an approved and operational alternate means of navigation (VOR)
• If RAIM, alternate navigation must be monitored only when RAIM is lost 
• If no RAIM
• Alternate navigation must be actively monitored 
• Alternate airport must have other than GPS approach
  
  
• WAAS receivers can be primary throughout the flight
  
  

Radar

• Primary radar function 
• Displays aircraft by reflection
• Reflection includes only range and bearing to the radar
  
  
• Radar limitations

• Radio waves can be bent/interfered by
• Ground obstacles
• Heavy clouds
• The smaller the aircraft, the smaller the return signal
  
  
• Transponder 

• Used with secondary radar to improve coverage and include altitude 
• Need mode c to report altitude
• How they work and how to use them
• ATC radar sends signal → transponder receives signal and sends coded reply
  
  
• Regulatory considerations 
• If transponder installed, it must be on at all times in controlled airspace
• Altitude reporting must be on in A,B,C airspaces
• Within 30 nm of bravo up to 10000 feet msl
• Above B and C up to 10000 feet msl
• Above 10000 feet msl except below 2500 agl
  
  
• ADS-B - Automatic dependent surveillance broadcast 

• AC broadcasts a message on a regular basis
• Includes position, speed, and other info
• Reports based on satellite navigation system
• The broadcast report is called ADS-B out
• Basic about ADS-B
• Other aircraft systems can receive the report/info if they have ADS-B IN
• Can be used to obtain NOTAMS, weather, etc
  
  
• 91,225 
• January 1st 2020 ADS-B out will be a required for all aircraft's in the same airspace's where transponders are needed
  
  
  
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