NavComms Flashcards
What is the frequency range used for Aviation Navigation?
108 - 117.975 MHZ
What is the frequency range used for Aviation Communication?
118 - 136.975 MHZ
What frequency range is used for Aviation International Communication?
Up to 151.975 MHZ
What are the 3 types of carrier wave propagations?
Ground Waves
Sky Waves
Spaces Waves
What is the frequency range for Ground Waves?
3 KHz to 3 MHz
What is the frequency range for Sky Waves?
2 MHz to 25 MHz
What is the frequency range for Space Waves?
30 MHz and above
Which propagation wave does this describe?
-Follows the curvature of the earth
-Transmitter power determines the range
-Up to approx. 1000 miles is typical
-Surface conditions will affect range (mountainous
poor range, flat surface – best range)
Ground Waves
What propagation wave does this describe?
-Travels in straight lines from the source, but can reflect off the Ionosphere to travel further, this
reflection creates a “Skip Zone” where signal is not received.
-Atmospheric conditions determine range and frequencies affected
Sky Waves
What propagation wave does this describe?
- Line of sight only
- Due to their high frequencies, they will not be reflected by the Ionosphere, but mountains, buildings, etc. will Block the signal.
Space Waves
What is an antenna?
A conductor that radiates the energy from the transmitter into the atmosphere. It also can be used to receive passing electromagnetic waves from the atmosphere.
What are the 3 basic types of antennas?
Marconi Monopole
Hertz Dipole
Dummy
What type of antenna does this describe?
-Typically, a vertical metallic rod, approx ¼ wavelength in length.
-Must have a ground plane.
-Or may be horizontal, which may be referred to as a Long Wire type
Marconi Monopole
When an aircraft antenna installation is
required to be grounded, where is it grounded to?
It is grounded to the airframe structure.
An ADF system uses what two antennas?
A loop antenna and a sense antenna.
The transmission lines must be:
(In regards to length)
Kept as short and direct as possible.
When bending coaxial cable, the bend radius should be at least ___ times the diameter of the cable.
6
When installing coaxial cable, secure the cable firmly along its entire length at intervals of:
approximately every two feet
What are waveguides used for?
Used in the higher frequency ranges (UHF +), to direct signal energy to the
antenna in Radar systems.
Waveguides are often filled with what to prevent moisture from accumulating and forming oxidation on the inner surfaces?
Nitrogen gas
What does a transmitter-microphone do?
Converts sound energy (mechanical–pressure waves) into varying electrical energy
What are the 2 basic types of transmitter-microphones?
Dynamic
&
Electret
What is a variable capacitor with a permanently polarized dielectric between 2 moveable plates, known as?
Electret Microphone
(most common used in Aviation)
FCC no longer requires individual operator licenses to operate airborne radio equipment.
However, an FCC radio station license is required to be what?
Plainly displayed in the aircraft if it is to be operated outside of the US.
Where is the VHF Comm antenna typically located?
On top or bottom of the fuselage
What does ACARS stand for?
ARINC Communication Addressing and Reporting System
What does ARINC stand for?
Aeronautical Radio Inc
AUTOMATIC DIRECTION FINDER (ADF) USES INPUTS FROM WHAT TWO DIFFERENT
ANTENNAS?
LOOP & SENSE
RMI IS USED TO SHOW WHAT?
THE MAGNETIC BEARING OF TWO RADIO STATIONS ON ONE INDICATOR
ON A PHASE COMPARISON SYSTEM - NORTH IS ______
SOUTH IS ________
North is in phase
South is 180° out of phase
THE LINES DRAWN FROM THE VOR STATION ARE CALLED WHAT?
RADIALS
WHAT ARE THE 3 TYPES OF VOR ANTENNAS?
WHISKER TYPE
TOWELL BAR TYPE
BLADE TYPE
What does the Instrument Landing System (ILS) do?
GUIDES THE AIRCRAFT DOWN A SPECIFIC COURSE FOR SMOOTH CONSISTENT LANDINGS.
What frequency range does the Localizer work in?
108 - 112MHz
What frequency range does the Glideslope work in?
329 - 335 MHz
What frequency do the Marker Beacons work on?
75MHz
What does the Localizer do?
DIRECTS THE PILOT ALONG THE CENTER LINE OF THE RUNWAY.
(PROVIDES HORIZONTAL GUIDANCE/DISTANCE)
WHAT SYSTEM SHARES THE RECEIVER & ANTENNA OF THE VOR?
Localizer
What does the Glideslope do?
PROVIDES CORRECT ANGLE OF DESCENT DOWN TO THE RUNWAY.
(PROVIDES VERTICAL GUIDANCE)
WHAT IS AUTOMATICALLY RECEIVED WHEN THE LOCALIZER IS TUNED IN ON VOR?
Glideslope
What do Marker Beacons do?
INFORMS THE PILOT HOW FAR FROM THE END OF THE RUNWAY THE AIRCRAFT IS
What is the distance, color, and frequency of the Outer Marker Beacon?
ABOUT 4 - 7 MILES OUT
BLUE LIGHT
SERIES OF 400 HZ DASHES (- - - - - -)
What is the distance, color, and frequency of the Middle Marker Beacon?
ABOUT 3,500 FEET FROM RUNWAY
AMBER LIGHT
1300 HZ TONE OF DOTS & DASHES ( . - . - . - . )
What is the distance, color, and frequency of the Inner Marker Beacon?
ABOUT 1800 FEET FROM RUNWAY
WHITE LIGHT
3,000 HZ TONE SERIES OF DOTS ( . . . . . . )
WHAT DO MANY DME UNITS GIVE INSTEAD OF A TRUE HORIZONTAL GROUND DISTANCE?
Slant Range
WHY MUST GROUND STATIONS DELAY THE REPLY SIGNAL FOR 50 MICROSECONDS?
TO ALLOW FOR CLOSE RANGE OPERATIONS
HOW IS GLOBAL POSITIONING SYSTEM (GPS) NAVIGATION ACCOMPLISHED?
THROUGH THE USE OF NAVSTAR SATELLITES MAINTAINED BY THE US GOVERNMENT
GPS CAN BE USED ON ITS OWN OR IT CAN BE INTEGRATED INTO OTHER NAVIGATION SYSTEMS LIKE:
VOR/RNAV, IRS OR FLIGHT MANAGEMENT SYSTEMS
WHAT ARE 3 ELEMENTS OF THE GPS SYSTEM
SPACE SEGMENT (SATELLITES)
CONTROL SEGMENT
USER SEGMENT
THE SPACE SEGMENT CONSISTS OF HOW MANY SATELLITES?
24 SATELLITES (21 ACTIVE AND 3 SPARES)
What do LAAS and WAAS do?
ALLOW FOR PRECISE CIVIL GPS BASED APPROACH AND LANDING SYSTEMS (AVSAT)
WHY WAS THE WIDE AREA AUGMENTATION SYSTEM (WAAS) DEVELOPED?
TO INCREASE THE ACCURACY OF GPS
What does a WAAS require?
A WAAS ENABLED GPS RECEIVER
What does WAAS reduce?
REDUCES POSITION ERRORS TO 1-3 METERS BOTH LATERALLY AND VERTICALLY
WAAS CONSISTS OF ____ PRECISELY SURVEYED GROUND STATIONS.
25
How does an ATC Transponder work?
IT TRANSMITS TWO SETS OF “INTERROGATION” PULSES OF UHF ENERGY (1030 MHz ) INTO THE ATMOSPHERE FROM THE GROUND STATION USING A SECONDARY SURVEILLANCE RADAR SYSTEM
IF THE INTERROGATION SIGNAL SENT FROM AN ATC TRANSPONDER IS RECEIVED BY AN AIRCRAFT, WHAT HAPPENS NEXT?
A “REPLY” SIGNAL IS AUTOMATICALLY RETURNED TO THE STATION ON 1090 MHz
What allows the pilot to confirm operation of the ATC Transponder?
A REPLY LIGHT WILL BE VISIBLE ON THE PANEL
What does Mode A display?
THE PILOT SELECTED I.D. CODE
What does Mode C display?
THE I.D. CODE AND PRESSURE ALTITUDE OF THE AIRCRAFT IN INCREMENTS OF 100FT. (CAN ALSO USE OUTPUT FROM ENCODING ALTIMETER)
What is used with Mode S?
USED WITH TCAS SYSTEMS FOR AIRBORNE BASED COLLISION PREVENTION
What does the IDENT button do?
IT’S ACTIVATED BY THE PILOT AND “HIGHLIGHTS” THE MARKER REPRESENTING THE AIRCRAFT’S IDENTIFICATION ON ATC’S DISPLAY
What are the 5 ATC transponder codes to be aware of?
0001 = NUCLEAR ATTACK.
1200 = VFR FLIGHT.
7500 = HIJACK.
7600 = LOST COM.
7700 = EMERGENCY
FAR 91.413 REQUIRES AN ATC TRANSPONDER BE TESTED EVERY ____
CALENDAR MONTHS.
24
What FAR gives the procedures for testing an ATC Transponder?
FAR 43, APPENDIX F
What does TCAS stand for and what does it do?
TRAFFIC ALERT COLLISION AVOIDANCE SYSTEM.
MONITORS THE AIRCRAFT’S SURROUNDING AIRSPACE & WARNS OF AN IMPENDING MID-AIR COLLISION.
What is a Radar Altimeter?
AN AIRBORNE FREQUENCY-MODULATED CONTINUOUS WAVE INSTRUMENT USED TO MEASURE ALTITUDE ABOVE TERRAIN
What is the range of a Radar Altimeter?
0 TO 2,500 FEET.
What frequency range does the Radar Altimeter work in?
4250 – 4350 MHz
How does a Radar Altimeter work?
A SIGNAL LEAVES THE AIRCRAFT AND BOUNCES OFF THE GROUND AND RETURNS. THE TIME DIFFERENCE DETERMINES DISTANCE.
(WATER AND HEAVILY FOLIATED AREAS WEAKEN THE RETURN SIGNAL)
WHAT IS THE CAUSE OF A MAJORITY OF AVIATION ACCIDENTS?
“CONTROLLED FLIGHT INTO TERRAIN”
WHAT SYSTEM IS TIED INTO FLAPS, LANDING GEAR, RADAR ALTIMETER, ETC?
GPWS
What is an Emergency Locator Transmitter (ELT)?
A SELF-CONTAINED RADIO TRANSMITTER THAT AUTOMATICALLY BEGINS TRANSMITTING DUE TO A SEVERE IMPACT PARALLEL TO THE LONGITUDINAL AXIS.
What frequencies do the TSO C91 and C91a ELTs transmit on?
TSO C91 - 121.5 MHz
C91a - 243 MHz
(A way to remember these numbers: 121.5 x 2 = 243)
What is the transmission signal wattage and distance for the C91 and C91a ELTs?
.75 Watts with an approximate range of up to a 100 mile radius
What is the most up-to-date version of the ELT?
TSO C126
What frequency does the TSO C126 ELT work on?
406.025 MHz
What is the wattage of the transmission signal from a TSO C126 ELT?
5 Watts
WHERE IS THE PREFERRED LOCATION OF THE EMERGENCY TRANSMITTER?
AS FAR AFT AS PRACTICAL, BUT FORWARD OF VERTICAL FIN
121.5 MHZ ELT BATTERIES MUST BE CAPABLE OF FURNISHING POWER FOR SIGNAL TRANSMISSION FOR AT LEAST __________
48-50 HOURS
ELT BATTERIES MUST BE REPLACED WHEN ____% OF THEIR USEFUL LIFE OR WHEN THE TRANSMITTER HAS BEEN IN USE FOR MORE THAN __ ________ ______ AS ESTABLISHED BY THE MANUFACTURER (FAR 91.207c)
50% of their useful life or more than 1 cumulative hour
How long does the Flight Data Recorder (FDR) continuously record at least 88 channels of flight related parameters?
25 HOURS
What is the primary purpose of the autopilot system?
TO RELIEVE THE PILOT OF CONTROL OF THE AIRCRAFT DURING LONG PERIODS OF FLIGHT.
What are the 4 basic systems of autopilot?
SENSING ELEMENTS (error sensing)
COMPUTING ELEMENTS (correction)
OUTPUT ELEMENTS (follow-up)
COMMAND ELEMENTS
What is the function of the Sensing Elements?
DETECTS WHEN THE AIRCRAFT IS NOT IN THE CONDITION REQUESTED.
SENSED BY GYROS FOR ATTITUDE AND HEADING.
When an error is sensed during autopilot, a correction is needed. What performs this correction?
A servo
What are 3 ways that servos can be operated?
Hydraulic
Electric
Both
What is the purpose of the Output Elements?
STOPS THE CONTROL SURFACE MOVEMENT WHEN THE SURFACE HAS DEFLECTED THE PROPER AMOUNT
What are the 2 basic types of Output Elements?
RATE
&
DISPLACEMENT
RATE =
AMOUNT OF TIME
DISPLACEMENT =
HOW FAR
What are the 3 channels of the autopilot system?
Aileron
Rudder
Elevator
What should be done before engaging the autopilot?
ALLOW THE GYROS TO COME UP TO SPEED AND THE AMPLIFIER TO WARM UP
What does the Flight Management Computer do?
MONITORS FLIGHT PARAMETERS AND PERFORMS AUTOPILOT FUNCTIONS
What is a Dutch roll?
A COMBINATION YAWING & ROLLING OSCILLATION THAT AFFECTS MANY SWEPTWING AIRCRAFT
How is a Dutch Roll counteracted?
A Yaw Damper system
What is the formula to compute the load of an antenna?
DRAG=.000327 X FRONTAL AREA (Sq. Ft) X VNE2
(VNE = Never Exceed Speed)
WHY IS A GASKET OR SEALANT NORMALLY INSTALLED BETWEEN THE ANTENNA AND THE AIRCRAFT SKIN?
TO PREVENT THE ENTRY OF MOISTURE INTO THE AIRCRAFT FUSELAGE