Objective

The student should leave with an understanding of aviation navigation equipment and systems, and be able to apply that knowledge to flight scenarios.

Elements

• Radio theory
• Tuning & identifying navaids
• CDI display
• VOR
• DME
• ILS
  • Localizer
  • Glideslope
  • Marker beacons
• NDB
• GPS

Schedule

Introduction	05
Main body	50
Application	15
Conclusion	05
Total	1 hour 15 minutes

Equipment

• pen and paper
• Instrument Flying Handbook and The Pilot’s Manual: Instrument Flying
• instrument procedure charts
• laptop with flight simulator and internet access

Online resources

• Tim’s Navigation Simulator works with multiple technologies
• Dual VOR trainer shows how to triangulate
• VOR simulator also has LOC and GS functionality
• Selkirk IFR trainers
• AIM Chapter 1: Air Navigation
• Global Positioning System

Instructor actions

• Introduce and motivate with the question of how we navigate without visual references
• Review private-level knowledge of the VOR and GPS systems using guided discussion
  • evaluate existing understanding of tracking and intercepting
• Describe new navigation systems and their operation in a predominantly lecture format
• Illustrate techniques using Tim’s simulator
• Review each system before moving on to the next
• Evaluate student knowledge with questions emphasizing understanding rather than rote
  • Have the student solve multiple scenarios
• Conclude with an oral quiz, identifying and correcting errors

Student actions

• Arrive with completed homework assignment
• Maintain active involvement by responding to questions and taking notes
• Guide the instructor through the intercepting and tracking of several simulator scenarios
• Complete an oral quiz and demonstration of the concepts

Completion standards

The lesson will be complete when the student can describe navigation systems and equipment – and demonstrate an understanding of the techniques required to smoothly and accurately intercept and track various navigation systems – with minimal instructor guidance.

Teaching outline

Basic radio principles, IF 181 & IFH 7-1

• Waves
  • ground waves are useful for navigation, as they remain extremely consistent
  • sky waves are primarily used for long-distance, low-power communications, due to unreliability (80-90%) of the ionosphere’s reflecting properties
  • space waves are powerful enough to penetrate the ionosphere without being refracted or reflected, and are used for most aviation navigation
• Interference
  • low-frequency equipment is more susceptible – ADF, LORAN
  • precipitation static
  • if it’s heard on comms, it could be affecting nav

Course Deviation Indicator

• Visual reference showing relationship to chosen course
  • set with OBS knob
• Works with VOR, GPS, and ILS systems, usually including glideslope
• Included in an HSI
• 2° of deviation per dot
  • total range is 10° left or right of course, halved with an ILS
  • 1° off course is 1/2 nm off course at 30 nm range

VHF Omnidirectional Range, IF 273 & IFH 7-8

• Most common form of navaid, and relatively simple to use
• Very High Frequency band, between 108.0 and 117.3 MHz
• 360° worth of radials – one every degree
  • difference between TO and FROM
  • accuracy is generally within 1°
  • radials are the magnetic bearing outbound from the station
• Two signals
  • reference phase (360° radial)
  • variable phase (_electronically_ rotated at 1,800 rpm)
• VOR receiver measures phase difference
  • compares to OBS setting and moves the needle
• 3 service volumes guarantee clear signal without interference:
  • High altitude (HVOR): complex shape, good to a maximum distance of 130 nm and 60,000 ft
  • Low altitude (LVOR): consistent 40 nm range and 18,000 ft
  • Terminal (TVOR): 25 nm range and 12,000 ft; generally used as approach aids
• Morse identifier transmitted every 10 seconds, along with (generally) voice broadcast like FSS, AWOS, or HIWAS
• Aircraft equipment must be checked every 30 days prior to IFR flight
  • log should include date, place, pilot or inspector’s name, and bearing error
  • test types:
    1. VOT – 180° TO or 360° FROM, ±4°
    2. ground, ±4°
    3. air, ±6°
    4. dual VOR, 4° max between indicated when centered

Intercepting and tracking – IF 273 and IF 357

• Tune VOR frequency, checking ident and flag
  • set OBS to desired radial course
  • select the VOR or GPS nav source
  • TUNE, IDENTIFY, TWIST, and SELECT
• Determine where we are relative to the station
  • center the CDI with a FROM flag
  • radials are always the FROM indication
• Intercepting and tracking with VOR and GPS
  • turn the CDI to the course
  • check the TO/FROM indication – does it make sense?
  • choose an intercept course between 30° (close) and 60° (far)
  • remember that at 30 nm from the VOR, every degree is 1/2 nm
  • turn inbound soon enough to roll out on course
• Illustrate with Tim’s simulator!

Distance Measuring Equipment, IF 207 & IFH 7-13

• Determines the slant range to the DME station
  • hypotenuse of the aircraft’s actual distance and altitude
  • errors show up when extremely close
  • accurate as long as we are 1 nm away for every 1,000 ft of altitude above the station
• Display unit shows distance in nm; our units also show ground speed and eta
• Airborne transmitter (interrogator) broadcasts a signal
  • this is picked up by ground stations (transponder)
  • ground station replies to the aircraft
• The DME hardware measures the time lapse
• Ground stations are limited to approximately 100 aircraft at a time
  • UHF equipment, generally colocated with a VOR as a VOR/DME

Arcing – IF 553

• “Arc northwest” – what does the phraseology mean?
• Used as a transition to a VOR or ILS approach
  • essentially, we’re drawing a constant-radius circumference
  • flown as a series of short, straight segments with heading changes
• Prior to entry, tune and identify
  1. set up the OBS to read TO the station (with two, set the second to the final approach course) – make sure we’re not using the GPS
  2. 1/2 to 1 nm from the arc, turn in the arc direction – generally 90° from the intercept heading
  3. twist the OBS 10° ahead – we want to cross the next radial
  4. as the CDI centers, turn 10° in the direction of the arc
  5. twist the OBS another 10° ahead and repeat
• when two dots from centering on the approach course, or when crossing the lead-in radial (on some approaches), start a standard rate turn to intercept
• Illustrate with Tim’s simulator, using approach terminology

Instrument Landing System, IF 309 & IFH 7-27

The ILS is a precision approach, providing both lateral and vertical guidance down a predetermined flight path.

• Uses a system of ‘lobes’; overlapping points define the approach
• Four parts make up the ILS in actual use:
  • localizer provides lateral (directional) guidance
    • operates between 108.10 and 111.9 MHz
    • broadcast from the shed at the non-arrival end of the runway (illustration from IFH 7-28)
  • glideslope provides vertical guidance
    • broadcast from antennas located approximately 1,000 ft from the approach end
  • marker beacons
  • approach lighting systems
• DME, radar, and LOM beacons can also be included in or required for ILS approaches

Nondirectional Radio Beacon, IF 213 & IFH 7-3

• 190 to 535 kHz
• transmit awos or voice poorly
• morse identifier must be listened to at all times
• components (old school)
  • two antennas, loop (directional) and sense (omnidirectional)
  • loop aligns with the radio waves
  • sense detects and tunes audio ident
  • somehow makes it work
• component (new)
  • solid-state barnacle thing on the bottom of the fuselage
• service volumes
  • 15 nm – compass locator
  • 25 nm – MH
  • 50 nm – H
  • 75 nm – HH
• accuracy factors
  • coastal effect – waves are bent crossing a coastline at an angle
  • mountain effect – mountains reflect waves
  • thunderstorm effect – acts as a station; needle points to lightning
  • night effect – lowered ionosphere refracts low-frequency signals
  • interference – from radio stations or other NDBs

Intercepting and tracking – IF 213

• Tune the NDB frequency, identify, and make sure it’s in the ADF mode
  • leave the ident on the whole time because ADF is awful
  • if the ident ceases, we can’t consider it usable for navigation
• Relative bearing is the angle between our heading and the NDB itself
  • MH + RB = MB to the NDB
  • MH + RB – 180 = MB from the NDB
  • with a rotating ADF card, we can align it to our heading indicator and determine RB that way
• Station passage is indicated by the needle flipping – may be fast or slow, depending on our position
• Intercepting a magnetic bearing
  1. parallel the bearing we’re going to intercept
  2. double the current RB, to a max of 90°, to get our intercept angle
  3. intercepting outbound, tail will rise; inbound, the head will fall
• Only in no-wind situations can we simply point at the NDB and track
• With crosswinds of any kind, we’ll need to figure out our wind correction and bracket the course
  1. find the current MB to or from the NDB
  2. double the off-course amount to get a correction angle
  3. crossing the course, halve the correction angle as a wind correction
  4. correct as needed, noting the headings which freeze our intended MB

Global Positioning System, IF 361 & IFH 7-21

• A satellite navigation system, GPS provides a primary means of navigation and can supplement or replace IFR approach systems
  • 24 Navstar satellites, orbiting in geostationary positions at 11,000 miles, form the space element
  • at least 5 satellites are always in view
  • a network of monitoring stations ensure accuracy and form the control element
  • antennas and receiver units form the user element, and can be kept up to date with the appropriate database
• The system works on the principle of time lapse, much like DME
  • by comparing the satellite-broadcast, pseudo-random timing signal from each satellite in view, the unit can determine location
  • five satellites, or four satellites and a barometer setting, are required for accurate detection of integrity anomalies
• RAIM requires an additional satellite to isolate the corrupt signal
  • without a RAIM capability, there’s no way to tell if it’s accurate
  • set the current barometer info in our Garmin units – it gives us an extra margin of error with RAIM
• Panel-mount, IFR-certified GPS units can substitute for ADF and DME when:
  1. determining position over a DME fix (for example, on approach)
  2. flying a DME arc
  3. navigating to and from an NDB or LOM
  4. determining position over an NDB or LOM
  5. determining position over an NDB on a VOR or LOC course
  6. holding over an NDB or LOM
• Intercepting and tracking same as VOR

Worksheet

1. How do we know when we have the course set up right?
2. Why do we have a navigation checklist, and what is it?
3. How can we determine our intercept angle?
4. Why would we arc with a TO indication? Would FROM change things for us?
5. Would we always use the 10 and 10 method for arcing? Why not?