AV03 Comm Facilities and Navaids Flashcards
Wave Length
Distance from peak to peak`
Cycle
period in which a wave rises from zero to crest then falls through trough and rises to zero again
Amplitude
height of the wave crest from zero
Carrier
transmitted radio wave of constant frequency and amplitude on which intelligence is added
Frequency
number of cycles (waves) that pass a given point in a specific amount of time. (Hz is cycles per second)
Name two most common types of modulators
Amplitude Modulation (AM) Frequency Modulation (FM)
Frequency Bands of NDB’s
LF, 190-415kHz and MF, 510-535kHz
What is the HF frequency used for air-ground communications in remote areas of Canada?
5680 kHz
VHF frequencies used for VOR’s and ILS
108.00-117.95 MHz
VHF frequencies used for civil aviation voice communication
118.00-136.00 MHz
Name frequency band used for DME’s TACAN’s and glide path.
UHF (300MHz-3000MHz)
What is the UHF Frequency used for emergency air-ground communications
243.0 MHz (considered UHF despite technically not being in UHF range)
Three types of Radio wave propagation
Direct Wave, Sky Wave and Ground Wave
Advantages of LF, MF and HF
Long range (Ground and Sky Waves) Site location not as important compared to VHF
Disadvantages of LF, MF, and HF
Subject to atmospheric interference
Bulky equipment
Subject to fading
Stations interfere with one another
Advantages of VHF
Virtually free fro static
Not subject to fading
Lighter equipment
Higher Fidelity
Disadvantages of VHF
Line of sight required
Man-made noise interference
Textual form digital communication displaying to both pilot and controller
CPDLC - Controller Pilot Data Link Communication
Components of Data Link Communication
Mode S secondary surveillance radar
Communication satellites
VHF data links
Mode S
Secondary Surveillance Radar System that provides two-way data communications capability for air traffic, flight information and surveillance services
SATCOM
Satellite Communications used in oceanic and remote areas
VHF Data Link
widely used for aircraft operations and for limited flight information and air traffic services. Can also provide cockpit weather graphics information from ground based weather radar
One degree of latitude is equal to what distance
60 NM
March Airport (CYMR) Coordinates
51 degrees 14 minutes 52 seconds North
96 degrees 00 minutes 06 seconds West
Bearing
The direction of one location from another. Angular measurements from 0-360 degrees.
Can be True, Magnetic, Relative or Compass bearing.
Heading
The direction the aircraft is pointed. 0-360 degrees.
Can be True, Magnetic, Compass or Grid.
Variation East
Magnetic less the true (Magnetic least)
Variation West
Magnetic greater the true (Magnetic best)
Isogonic Lines
Dashed lines on charts depicting areas of equal magnetic variation.
Agonic Line
Line joining points of zero variation
Deviation
Angular Difference between magnetic North and compass North for a specific aircraft
The two systems of radio aids.
Info displayed in the aircraft
Info available by voice communication from the ground
The three dimensions position is given in.
Distance
Bearing
Altitude
Reciprocal
Opposite of a given bearing
Track
Direction the aircraft is actually moving (not necessarily the direction it is pointing)
What Navaid transits a 1020Hz monotone interrupted every 7.5 seconds with two or three letter morse code identifier in all directions?
NDB
Auxiliary Codes
Letter code appearing after frequencies of navaids appearing either singly or in multiples.
Auxiliary Code “A”
ATIS
Auxiliary Code “T”
ATC can transmit on this nav frequency but not receive
Auxiliary Code “M”
NDB power output 50 to less then 2000 watts
Auxiliary Code “H”
NDB power output 2000 watts or more
Auxiliary Code “L”
NDB power output less then 50 watts
Auxiliary Code “Z”
75MHz location or fan marker
Uses of an NDB
En route navigation
Holding facility
IFR approach
Fix determination
What is ADF?
Automatic Direction Finder.
An airborne radio compass which can home in on NDB’s
(mandatory for IFR flights in uncontrolled airspace)
What is the ADF Formula?
Track to NDB = Heading + Relative Bearing
Bearing from NDB = Track to NDB Reciprocal
What are the causes of erroneous ADF readings?
Electrical storms Night Effect Mountain Effect Coastal Refraction Sense Antenna Failure
What is Night Effect?
Oscillation of ADF needle occurring right after sunset or just before dawn
What is Mountain Effect?
Erroneous ADF readings caused by radio waves reflecting off mountains
What is Coastal Refraction?
Erroneous ADF readings caused by radio waves refracting off the coastline
What happens when the sense antenna fails?
The ADF needle will rotate constantly in one direction
VOR Frequency Range
112.0 - 117.9MHz
How many letters used in VOR identifiers?
three
Radial
A bearing from a VOR, TACAN or VORTAC facility
What a VOR broadcasts
3 letter Identifier every 7.5 seconds in morse code
Radiates 360 range legs (radials)
What are the uses of a VOR?
En Route Navigation
Holding fix
IFR approach
Determination of intersection
Advantages of VOR
360 courses (radials) Little interference accuracy + or - 2 degrees easy to use Magnetic bearings Visual presentation positive tuning
Disadvantages of VOR
Line of sight transmission
On some radios, VOR receiver cuts out when transmitter is used
What does a DME do?
Airborne DME transmitter sends radio signal to ground DME facility, which sends a reply back on different frequency. Airborne receiver measures amount of time required for the round trip signal and translates into distance (slant range) from aircraft to ground station in nautical miles, automatically and continuously
What is the ICAO regulated minimum accuracy of a DME?
Within + or - 1/2 mile or 3% of distance, which ever is greater
Frequencies used by DME’s
UHF 960-1215MHz
However it’s frequency is paired with a VOR or ILS frequency so most aircraft equipment will provide automatic selection of DME when VOR is selected.
Frequency assigned and published as channel number
eg ch85.
Effective range of DME
about 200NM depending on altitude
How DME’s are combined with other navaids
As integral part of TACAN
With VOR to enhance en route position determination and increase number of radio fixes in a terminal area
As an alternative to ILS MF/LF beacons
As a basis for area navigation through airborne computing of VOR/DME signals from a collocated source or DME signals from two suitably located locations
What is a DME Arc?
A course flown at a constant DME distance around a navaid such a VOR (orbit)
Advantages of DME
Position of aircraft presented to pilot more accurately than with VOR or ADF fixes
Pilot can quickly and accurately estimate ground speed when flying directly toward or away from DME
More precise position given by DME can be used by controller to radar identify a flight with out using identifying turns
Separation of IFR flights can be safely reduced
Describe a TACAN
Tactical Air Navigation. Navaid used primarily by the military for en route, non precision landings and other military applications. Measures bearing and range from ground station in same manner as a VOR/DME.
Short Range
Two Elements of TACAN
Airborne Receiver (Interrogator) Fixed Ground Transponder (beacon or station)
Frequencies used by TACAN
Air - Ground 1025-1150MHz
Ground - Air 962-1024MHz and 1151-1213MHz
LF range
30-300kHz
MF range
300kHz-3000kHz
HF range
3-30MHz
VHF Range
30-300MHz
UHF range
300-3000MHz
What is VORTAC?
Combination of civil VOR and military TACAN at the same site.
How does VORTAC serve military and civil aviation?
Civil in VHF bands and military in UHF bands
Describe ILS
Instrument Landing System
Is primary international precision approach system approved by ICAO.
Provides precise horizontal and vertical guidance to the runway.
What are the ground components of ILS
Localizer for horizontal portion
Glide Path for vertical portion
NDB or DME Fix along approach path
Frequencies used by Localizer
VHF 108.1 - 111.9MHz
What are the Yellow and Blue Sectors in regards to the localizer?
If in Yellow Sector, aircraft to left of localizer.
If in Blue, to the right
Location of Localizer
Extended centre line of principle ILS runway, short distance from opposite end of approach
Localizer Ident
three letters beginning with letter “I”
Frequencies used by Glide Path
UHF 329.3 - 335.0MHz
Glide Path channel always paired with Localizer channel
Location of Glide Path
approximately 1000’ from approach end of runway, offset approximately 400’ from centre line
What does GPS provide?
Reliable position and navigation information on timely basis in any weather condition when minimum of four usable GPS signals can be attained.
Also means of guidance approved in North Atlantic.
Two Systems GPS supports
RNAV
ADS-B
What is ADS-B?
Automatic Dependent Surveillance-Broadcast
Next gen surveillance tech that supports radar-like separation standards in areas where non radar (procedural) separation has traditionally been used, allowing more flexible routing and fuel savings.
What does ADS-B do?
Airborne ADS-B equipment relays to ground based receiver the exact geographical co-ordinates of the aircraft and displays the info on a surveillance screen at ATC.
GPS was developed by the US military. Do they charge for it’s use? And is there a threat of them cutting off service?
No. Presidential Statement was issued in 2004 making commitments to ensure the continued operation of GPS constellation, with uninterrupted access to it’s signals, free of direct user charges
Three segments of GPS
Space Segment
Control Segment
User Segment
Nominally, how many satellites in the GPS constellation?
24
Describe the orbits of GPS satellites
They orbit in six separate orbital planes twice a day at 10900 NM at roughly 7000 MPH. 4 satellites in each plane. This guarantees a minimum of 4 satellites in view at any given time.
Keeping time on a GPS satellite
each satellite has 4 atomic clocks giving accuracy of one billionth of a second
Three components of the Control Segment
Five monitor Stations (Hawaii, Kwajalein, Ascension Island, Diego Garcia and Colorado Springs)
Three Ground Antennas (Ascension Island, Diego Garcia and Kwajalein)
Master Control Station at Schriever Air Force Base in Colorado
Two frequencies of GPS
L1 and L2
L2 is encrypted for military use only
Precise Positioning Service (PPS)
Uses both L1 and L2. Military applications only. Accurate to within 5m
Standard Positioning Service (SPS)
Uses L1 only. Civil use. Accurate to 15m
Advantages of GPS
Accurate, global and three dimensions No environmental limitations Provides position info Inexpensive Reduced IFR spacing More efficient routing for VFR Increased safety Enormous future potential
Common Uses of GPS
Aviation Vehicle Tracking Vehicle Navigation Emergency Services Data Collection Marine Agriculture Recreation
Sources of GPS errors
Orbital Error Clock Errors Ionospheric and Tropospheric delay Multipath Errors Receiver Noise
Total accuracy affected no more then 25-50m
What is Orbital Error
When the satellite is not in the position it is predicted to be in.
What is Clock Error
When satellites clock and receiver clock are out of sink. A 10 nanosecond (0.00000001 second) error would throw the range off by 3m
What are Ionospheric and Tropospheric Delay
Delay in signal reaching receiver due to passing through charged particles in the atmosphere
What is Multipath Error
GPS signal bounces off nearby objects throwing the range out.
What is GPS Receiver Noise
When GPS receiver struggles to measure signal from satellites.
What capability must a GPS receiver have to be approved for IFR applications?
RAIM (Receiver Autonomous Integrity Monitoring)
Requires at least 6 satellites in view to detect unhealthy satellites and warn pilot of discrepancy
Can handheld GPS receivers be used by pilots?
Yes but VFR only and only as an accessory for VFR Navagation
Disadvantages of GPS
Over reliance
Antenna mounting issues causing signal loss
Database updates and Humane error
Precision GPS approaches still not widely available
Pronounceable 5-letter identifiers (LLLLL)
Assigned to airway intersections and oceanic control boundary intersections
4-Letter identifiers (CLLL)
Used to identify specific aerodromes (ie CYVR = Vancouver)
3-Letter Identifiers (LLL)
assigned to VOR, DME, ILS (ILS always starts with “I”), VORTAC and TACAN
2-Letter identifiers (LL)
Assigned to NDB and certain DME
3-Letter-Number Identifiers (CLL#) ie CKK7
Assigned to secondary Aerodromes that do not meet the requirements for a 4-letter ID but are still listed in CFS
Number Letter Identifiers (L#) or (#L)
Assigned to private navaids
VHF Emergency Frequency
121.5 MHz
UHF Emergency Frequency
243.0 MHz
En Route common frequency
126.7 MHz
HF Northern Areas frequency
5680 kHz
Flight Information common frequency
122.5 MHz
Vehicle control Frequency
122.6 MHz
ATC Frequency ranges
- 0-121.975 MHz
- 6-128.8 MHz
- 025-136.475 MHz
Approximate ranges of VHF radio communications at;
FL180
FL350
FL450
Altitude Air-Ground Air-Air
FL180 165NM 330NM
FL350 230NM 460NM
FL450 261NM 522NM
Air-Air double Air-Ground
4 methods to express direction
1) True - relative to True North
2) Magnetic - relative to magnetic North
3) Compass - Based off the A/C’s compass
4) Relative - position of an object relative to the direction the A/C is pointing
Bearing
Direction of one location from another. Angular measurements from 0 degrees - 360 degrees given in either True, Magnetic, Compass or Relative
Heading
Direction of which the longitudinal axis of the A/C is pointing in relation to North (True, Magnetic, Compass or Grid North)
True Bearing
Measured clockwise from True North
Magnetic Bearing
Measured clockwise from Magnetic North
Compass Bearing
Measured clockwise from Compass North
Relative Bearing
Measured clockwise from the heading of the A/C
Where do ADF needles always point?
They always point to the NDB and read clockwise from the nose of the A/C.
eg. needle points to 0 degrees, nose of A/C pointed directly at the NDB, if needle points to 180 degrees, tail of A/C points to the NDB
How to determine track to the NDB and the bearing from the NDB.
Add A/C heading (magnetic) to the relative bearing of NDB.
eg. A/C heading is 070 degrees and the relative bearing of NDB from the A/C is 230 degrees. The track to the NDB would then be 300 degrees magnetic.
The A/C would need to change heading from 070 to 300 to fly towards the NDB.
The bearing from the NDB would be the reciprocal of of the track to the NDB. So in this case the A/C’s bearing from the NDB would be 120 Degrees. (reciprocal of 300)
What is RMI?
Radio magnetic Indicator.
combination of gyro-slaved magnetic compass and an ADF indicator. Gives magnetic bearing directly.
A/C’s heading shown at top of instrument, while needle points to NDB.
eg. If number at the top is 270 and the needle is pointing to 120. The A/C is flying a heading of 270 degrees magnetic, and if the A/C alters course to a heading of 120 degrees magnetic, the A/C will be heading towards the NDB. At which point the needle will be pointing to the number at the top of the instrument which would then be 120
