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06-B: Navigation Systems and Radar Services

Knowledge

K1: Ground-based navigation (identification, orientation, course determination, equipment, tests, regulations, interference, appropriate use of navigation data, and signal integrity)

  • VOR
    • angular localization
      • VOR receiver measures flash/sweep time difference from the VOR sender to infer angles
      • thus, it obtains the aircrafts location as an angle between 0 and 359° degrees
      • the VOR display is ambiguous in that it centers the CDI needle at two angles
        • when the OBS is set to the measured radial and
        • when the OBS is set to its 180-degree reciprocal
      • the user can disambiguate the angle by reading the TO/FROM indication (only top angle + TO/FROM indcation pair gives the unique angle regarding the station)
      • no aircraft heading information is sensed
      • when centered and
        • when indicating FROM, the top angle is the radial FROM that station
        • when indicating TO, the top angle shows the bearing TO the station, i.e., the heading to fly to get direct to the station
      • TO/FROM vanishes
        • in the cone of confusion
        • at perpendicular OBS orientation
      • if, over time, we are flying to the station, but the needled is centered while indicating FROM (and vice versa)
        • we are in reverse sensing, i.e., the needle mirrors the turn direction needed to get back on track
    • radials vs bearings
      • an aircraft is on a radial FROM the station (this is how the radials are defined, as they emante FROM the VOR center)
        • radials are half-lines, i.e., the aircraft is on exactly ONE radial
        • radials are not inbound or outbound (if anything they are always outbound, but then it becomes a pleonasm to call it outbound radial)
        • but: we can fly/track the radial inbound or outbound (irrespective of what our display is showing)
      • the station has a bearing we can fly TO
    • componets
      • CDI: course deviation indicator
        • ignore where the bottom CDI tip is located it has no meaning
        • the CDI needle simply represents the path to fly and easily allows determining if we are right or left of path and by how many degrees
          • each dot = 2 degrees
          • 5 dots each side
      • OBS: omnibearing selector knob
      • TO/FROM indication:
        • TO
        • FROM
        • OFF and/or FLAG (90° or cone of confusion)
      • GPS or VOR source
    • in-flight usage
      • tuning the frequency
        • PUSH C/V button
        • tune frequency
        • switch from standby to active
        • pull ID button if needed
        • confirm morse code
        • deactive ID button
      • setting the VOR
        • navigating TO the VOR
          • configure the instrument to use VOR signals, not GPS signals (CDI toggle button on the GPS device)
          • find the straight line from current location to the VOR station
          • alternatives
            • read the radial on the near side and add 180° degrees to obtain the reciprocal OR
            • go along the straight line through the VOR to the other side to find the reciprocal (mnemonic: to go TO the VOR, you need to THROUGH the VOR)
          • verify the obtained reciprocal is a plausible bearing, i.e., plausible compass heading to fly as seen from the aircraft
          • center the needle by turning the OBS knob to that angle (number on top) with TO indication resulting in
            • CDI: centered
            • OBS: bearing to the station = heading to fly to reach the station
            • TO/FROM indication: TO
        • navigating FROM the VOR
          • configure the instrument to use VOR signals, not GPS signals (CDI toggle button on the GPS device)
          • find the straight line from the VOR to the destination
          • read the radial on that line between the VOR and the destination
          • confirm this radial is a plausible heading to fly to reach the destination
          • center the needle until it shows the radial (number on top) with FROM indication resulting in
            • CDI: centered
            • OBS: radial we want to track = heading to fly to reach the destination
            • TO/FROM indication: FROM
      • reading a random VOR display
        • configure the instrument to use VOR signals, not GPS signals (CDI toggle button on the GPS device)
        • note
          • TO/FROM indication
          • OBS angle
          • CDI deflection
        • convert this triplet into a radial on which the aircraft is located (if CDI deflection is not massive)
          • if FROM:
            • read the angle
            • if the needle is deflected to the left, we are right of path, i.e., we need to steer left, i.e., we will reduce our compass heading angle, i.e., our compass heading angle is too great, i.e., add the deflection (1 dot = 2° degrees of angular deviation from the sensed radial)
            • if needle is deflected to the right, subtract the deflection
          • if TO:
            • read the angle
            • if needle is deflected to the left, add the deflection
            • add or subtract 180 degrees to find radial
          • if OFF:
            • cone of confusion or perpendicular OBS setting +/- 90° from the current radial
        • quadrant visualization
          • draw dot on current the OBS setting
          • draw line through the dot and the VOR station
          • draw perpendicular line through the VOR statin
          • label resulting quadrants
            • annotate FROM on both quadrants touching the dot
            • annotate TO on both quadrants far from the dot
            • annotate left of course and right of course based on the side when gazing at dot from the perspective of the VOR
          • put aircraft into quadrant with corresponding TO/FROM indication and CDI needle deflection
      • reading and tracking a VOR
        • CDI needle represents path
        • check to learn the direction needed to reintercept the path
        • pick a heading
        • from the heading, pick a ground reference
        • fly the ground reference, or if none available, the heading to avoid chasing the lagging CDI needle
    • VOR checks
      • VOR test signal (VOT)
        • transmits 360 degree radial in all directions
        • usage
          • tune to airport's VOT frequency as published in the AF/D
          • tune OBS to 0/360 FROM or 180 TO
          • confirm CDI does not deviate more than +/- 4° (ground tolerance) from center
          • irrespective of position
      • check CDI alignment with VOR / Victor airway
        • airway tolerance: 6°
    • VFR Sectional symbol
      • hexagon: VOR
      • hexagon in box: VOR/DME
      • triangle: VORTAC
    • frequency band
      • VOR Frequencies are 108.00 to 117.95
      • ILS Frequencies are 108.15 to 111.95
      • ILS vs VOR frequency decoding path
        • ILS range and VOR range overlap in the lower range
        • ILS frequencies always have odd tenths
        • VOR frequencies always have even tenths
        • Navigation receiver chooses demodulator circuit based on the parity of the first decimal

  • VOR Figure 28

    • Illustration 6
      • situation
        • OBS: 210 radial
        • TO/FROM indicator: FROM
        • CDI: needle deflected left by 1 dot (2 degrees) / we are right of course
      • analysis
        • we are on FROM 230 radial
        • we are southwest of the station
      • 6:
        • display
          • TO/FROM indication: FROM
          • OBS: 210°
          • CDI: 1 dot (= 2 degrees left)
        • implications
          • we need to steer left to intecerpt the path, i.e., we are right of path, i.e. we are 210° + 2°
          • we flying outbound radial 212°
      • 1:
        • display:
          • TO/FROM indication: TO
          • OBS: 210°
          • CDI: needle 4 degrees (2 dots) to the right, we are left of path
        • implications
          • bearing TO the station is 206°, we are on outbound radial 26°
      • 4:
        • display:
          • TO/FROM indication: TO
          • OBS: 210°
          • CDI: needle 2 degrees (1 dots) to the left, we are right of course, and have to steer left
        • implications
          • steering left reduces bearing, we are too much bearing, the station has bearing 212°
          • bearing 212 is radial 32°
          • we flying on radial 32°

  • VOR Task: Which VOR indication is correct (Figure 28)

    • Figure xx:
      • given:
        • VOR tuned to Bonham VORTAC
        • Aircraft over Sulphur Springs
      • map plot
        • we are on radial 120
      • Analysis
        • exclusion principle
          • we are not on radial 210 nor on the reciprocal 030, thus it cannot be displays with centered CDI on these angles
            • 2
            • 5
            • 8
            • 9
            • remains: 1, 3, 4, 6, 7
          • 1, 4, 6 have CDIs that indicate deviations of maximally 2 dots = 4° degrees, but we are nowhere near the OBS-set radials 210
            • remains: 3, 7
          • 3 and 7 have not TO/FROM indication
            • matches perpendicular setting
              • 3: 120° radial per map - 210° set in the OBS = -90°
              • 7: 120° radial per map - 030 set in the OBS = 90°
          • we cannot possibly disambiguate between the 3 or 7, but show basically give the same information that we are perpendicular to the tuned setting, but 7 does not appear in the answers, but 3 does
    • Figure 26:
      • given:
        • VOR tuned to Jamestown
        • Aircraft over Cooperstown
      • map plot
        • we are on radial 025°
      • chart analysis
        • all VOR receivers are set to the OBS 210 or 030
      • exclusion principle
        • radial 025° is 5° from 030, thus we can exlude all charts that are centered
        • we are not in the cone of confusion, and the OBS is not tuned to 90° from the radial, thus we can exlude all situations where TO/FROM is off
        • remains
          • 1, 4, 6
      • deeper look at 1, 4, 6
        • we are approximately on radial 030, so we to be
          • approximately FROM 030 or
          • apprximately TO 210
          • illustation 6 shows FROM 210, we is not close at FROM 030
          • remains 1 or 4
      • deeper look at 1 and 4
        • 1:
          • TO/FROM indication: TO the station
          • OBS: 210
          • CDI: deflected right
          • analysis
            • Jamestown VOR has a bearing of 205°, i.e., we can fly 205° inbound to get to Jamestown
            • VOR suggestion: turn right to intercept 210° inbound bearing
            • however, if you draw down the bearings, you see you need to turn left to intecept 210°
            • this is not the situation we are in
        • 4:
          • TO/FROM indication: TO the station
          • OBS: 210
          • CDI: deflected left
          • analysis
            • assume we were flying bearing 210°, TO, CDI centered, on the 030 radial
            • assume we drifted to the right
            • we would end up on radial 025 and the needle would suggest to turn left again to reintercept FROM 030 = TO 210.
            • this is our situation

  • Figure 23:

    • given
      • 320° radial Savannah VORTAC
      • 184° radial of Allendale VOR
    • intersect
      • Southeast of Guyton

K2: Satellite-based navigation (equipment, regulations, authorized use of databases, Receiver Autonomous Integrity Monitoring (RAIM))

  • GPS
    • number of satellites
      • four sallites: minimum required for 3D position
      • fifth satellite: RAIM fault detection
        • flying without RAIM
          • navigation can deteriorate without being noticed
          • cross-checks required
      • sixth satellite: RAIM fault correction
    • technical limitations
      • jamming
    • portable GPS receivers
      • usually have no RAIM capabilityss
    • restrictions
      • GPS altitude should not be used as primary source of altitude data
      • without WAAS, GPS is not considered realiable, even less accurate than the installed altimeter
    • accuracy
      • traditional GPS: 15 meters
      • wide area augmentation system (WAAS): less than three meters at 95% of the time
    • availabity
      • both hemispheres
    • GPS databases
      • legal usability
        • can fly with an expired GPS database
        • but moving map dispaly must be disregarded when making critical navigation decisions
        • waypoints should be verified against a current source (Sectional, A/FD)

K3: Radar assistance to visual flight (VFR) aircraft (e.g., operations, equipment, available services, traffic advisories)

  • basic radar services in the terminal radar program

    • safety alerts
    • traffic adivsories
    • limited vectoring to VFR aircraft

  • traffic advisories

    • 12-hour clock
      • indications are based on ground track
      • controller is not aware of aircraft heading

K4: Transponder (Modes A, C, S) and Automatic Dependent Surveillence-Broadcast (ADS-B)

  • ADS-B Out requirement areas

    • Class A
    • Class E at and above 10'000 MSL excluding at and below 2500 AGL
    • within the lateral boundaries of Class B or Class C airspace and above its ceiling upward to 10'000 MSL
      • flight below C is permitted
    • Class-B Mode C Veil (30 NM radius)
    • Class E airspace at and above 3000 MSL over the Gulf of Mexico from the US coastline out to 12 NM

  • Mode A (Code 3/A)

    • minimally needed to squawk VFR (1200)

  • Class B and Mode-C veil (30 NM radius)

    • operable 4096-code transponder with
    • Mode C encoding altimeter
    • ADS-B Out

  • ADS-B In

    • FIS-B
      • Flight Information Service B
      • comprises
        • METAR
        • TAF
        • PIREP
        • Radar
        • etc.
      • can be used to botain weather updates for the desitination airport while of reach of the ATIS

  • TCAS not required

    • if used, TCAS resolution advisories must be followed even if this means deviating from ATC instructions

  • VORs

    • did research go too far?
    • To is the far side / to go TO the VOR, you need to go THROUGH the VOR
    • From is the close side