ATPL NAVIGATION Flashcards
(144 cards)
1
Q
What is a wavelength?
A
The number of cycles passing a given point in one second. (Expressed as Hertz (Hz)
2
Q
What is the amplitude of a radio wave?
A
The displacement of the peaks or troughs from a mid-point. (The greater the amplitude, the stronger the signal)
3
Q
In which planes are radio waves transmitted?
A
Horizontally and vertically.
4
Q
How must the antenna be polarised?
A
The receiving antenna must be polarised the same as the transmitting antenna. (i.e horizontal to horizontal etc.)
5
Q
What does the term modulation mean?
A
To modulate a radio wave means to create variation in the amplitude, frequency or phase. This is done using another waveform such as speech or music.
6
Q
What is one disadvantage of single sideband (SSB)?
A
The requirement for clarification or fine tuning due to the narrow bandwidth.
7
Q
What is the frequency, wavelength and usage of the VHF band?
A
30 to 300 Mhz, 10 to 1m and FM, voice and VOR navaids
8
Q
What is the frequency, wavelength and usage of the UHF band?
A
300 to 3000 Mhz, 100 to 10cm and voice and navigation
9
Q
How do direct waves travel?
A
Directly between the transmitter and the receiver
10
Q
How do surface waves travel?
A
Following the curvature of the earth (due to diffraction)
11
Q
What is a sky wave?
A
It is a radio wave that has been refracted & reflected by the ionosphere back to earths surface.
12
Q
What is the maximum theoretical range equation?
A
Theoretical VHF range in NM = √1.5*receiver altitude (ft)
13
Q
What heavily attenuates a radio wave signal and what causes the greatest attenuation?
A
Sand and ice/snow
14
Q
What is the skip distance?
A
The distance travelled by a radio wave from the transmitter to the point where it returns to the earth’s surface.
15
Q
How does a VHF Omni-directional Range (VOR) navaid work?
A
The VOR produces a radial pattern consisting of a 30Hz reference signal and a 30Hz variable phase signal. The aircraft receiver compares the PHASE DIFFERENCE between the arriving signals. Equipment inside the aircraft displays this information to the pilot.
16
Q
What are the errors associated with a VOR navaid?
A
“AVGAS” - Airborne equipment error, Vertical polarisation error, Ground station error, Aggregate error, Site/terrain effect
17
Q
Does the VOR read magnetic deviation or true deviation?
A
The VOR is calibrated for magnetic variation
18
Q
What error does a Doppler VOR eliminate?
A
Site/terrain effect (by use of FM not AM)
19
Q
How does an Non-directional Beacon (NDB) navaid work?
A
It radiates a non-directional carrier wave in the MF band with audio, Identifiable by morse code.
20
Q
What is a Locater?
A
A low-powered NDB often used in association with an ILS
21
Q
The onboard equipment (ADF) has two antennae. What are they called and what do they do?
A
The Loop Antenna - locates the aural null. The Sense Antenna - resolves the 180° ambiguity.
22
Q
What is the HATS formula?
A
Heading + ADF bearing = Track to station
23
Q
What are the errors associated with a NDB navaid?
A
“MINTCHAT” - Mount effect, Interference (co-channel), Night effect, Terrain effect, Coastal refraction, Height effect, Aircraft (quadrantal) error, Thunderstorms
24
Q
1 nautical mile equals how many feet?
A
6080ft
25
How does Secondary Surveillance Radar work?
A ground based interrogator transmits a repetitious signal requesting that aircraft transponders within range respond with a coded reply.
26
When is localiser interference possible?
When an aircraft takes off over the localiser antenna
27
When is glideslope interference possible?
When an aircraft lands on the same runway or flies across your glidepath on approach to an adjacent runway.
28
How do you calculate distance off track?
Track Error = Distance off / Distance along * 60
29
What is the definition of height?
The vertical distance of a level, point or object measured from a specified datum.
30
What is the definition of elevation?
The vertical distance of a point or level affixed to the surface of the earth.
31
What is the definition of Mean Sea Level (MSL)?
The average sea level for a particular geographical location.
32
What is the definition of altitude?
The vertical distance measured from mean sea level.
33
What is the definition of true altitude?
The actual height of an aircraft above mean sea level (Indicated altitude corrected for temperature error).
34
What is the definition of pressure altitude?
The height of an aircraft measured from the standard atmospheric pressure level of 1013HPA
35
What is the Pressure Altitude formula?
PA = Elevation + [(1013-QNH)*30]
36
What type of installation/instrument errors occur in the altimeter?
Instrument, Pressure, Time and Hysteresis
37
What type of non-standard atmospheric errors occur in the altimeter?
Temperature and barometric
38
What is the true altitude (temp. correction) formula?
True Altitude = 0.4% per degree of ISA deviation
39
What happens to the altimeter if the static system becomes blocked?
The pressure within the instrument remains constant and will read the height at which the blockage occurred.
40
What are four airspeed indicator errors?
Instrument, Pressure, Compressibility and Density error.
41
What does SAND stand for?
South accelerate, north decelerate
42
What does ONUS stand for?
Overshoot north, undershoot south (on east/west tracks)
43
When considering a directional gyro, what is apparent drift?
Drift due to movement over the earths surface (transportation) and the earths rotation. (MAX at poles ZERO at equator)
44
When considering a directional gyro, what is real drift?
Drift due to imperfections and bearing drag within the gyroscopic unit.
45
What are the advantages of a Radio Magnetic Indicator (RMI)?
Can be slaved to other systems - AP/FD, Minimises turning and acceleration errors, Minimises magnetic deviation, stable reference.
46
What are the disadvantages of a Radio Magnetic Indicator (RMI)?
Requires aircraft power, heavy, complex, expensive.
47
What is the main (remaining error) of a Radio Magnetic Indicator (RMI)?
Magnetic deviation.
48
What does pulse length determine?
The MINIMUM range of the weather radar. (It also determines RANGE RESOLUTION - the ability to distinguish between targets at the same altitude but different distances).
49
What is azimuth resolution? (Wx radar)
Azimuth resolution is a function of beam-width and range to target.
The radar is unable to distinguish a gap between two targets at the same range, less than the beam width.
50
What does the pulse repetition frequency (PRF) determine?
This determines the MAXIMUM range of the wx radar
51
What type of radar dish provides the best azimuth resolution?
A large one. (Provides a narrow beam)
52
When viewing a Wx radar cockpit display, what does close contouring between colours mean?
The closer the contouring the more severe the turbulence.
53
What is the recommended radar tilt position?
Parked to a tilt that allows a "sprinkling of ground returns"
54
What does the GREEN contour colouring indicate on a Wx radar display screen?
A weak return, however LIGHT to MODERATE turbulence and lightning possible.
55
What does the MAGENTA contour colouring indicate on a Wx radar display screen?
This indicates MODERATE to SEVERE turbulence.
56
What formations on the Wx radar can you consider to be associated with severe turbulence and hail activity?
Fingers, hooks, scalloped edges, u-shapes (horseshoe).
57
Regarding the RMI, what does constant oscillation of the annunciator mean?
The system is working properly and the gyro is hunting about the mean position.
58
What/how many types of gyros exist?
Four - space, tied, earth and rate gyros.
59
What types of instruments are the rate and earth gyro used in?
Turn co-ordinator and attitude indicator respectively.
60
Summarise drift and topple with the HORIZONTAL axis of a gyro at the poles and equator.
At the poles = NO topple, no drift. At the equator = NO drift, NO topple (north-south) and MAX topple (east-west)
61
Summarise drift and topple with the VERTICAL axis of a gyro at the poles and equator.
At the poles = NO drift, NO topple. At the equator = NO drift, MAX topple.
62
What is meant by the term wander?
Deviation from a set position in an axis gyro.
63
How many operational satellites make up the GPS constellation?
21 (3 spare).
64
How many satellites are required for an accurate position fix?
4.
65
GPS signals are so faint, they are weaker than the earths inherent background noise - true or false?
True.
66
Which is better for accurate readings HIGH or LOW GDOP/PDOP?
Low (better spacing of the GPS satellites provides a more accurate result).
67
With selective availability implemented, what is the worst case error?
100 metres (3x33m) - (33m with no GDOP allowance).
68
What are the existing "sole means of navigation" systems in AUS?
NDB, VOR, DME and INS.
69
What is required for approval of sole means of navigation?
ACARI - Accuracy, Coverage, Availability, Reliability, Integrity.
70
What is RAIM?
The ability for receiver units to detect faulty satellites by comparing position and time information. (RAIM stands for - Receiver Autonomous Integrity Monitoring)
71
How many satellites are required for RAIM?
MINIMUM 5. 6 to continue working i.e detect and exclude a faulty satellite.
72
What is Newton's First Law?
A body at rest will stay at rest OR uniform (constant) motion unless acted upon by an external force.
73
What is Newton's Second Law?
Acceleration of a body is directly proportional to the sum of the forces acting on the body (f=ma).
74
What is Newton's Third Law?
For every action, there is an equal and opposite reaction.
75
What is earth rate compensation?
A gyro's platform is forced to tilt in proportion to the earth's turning rate. (This varies with latitude & is 15.04° per hour at the equator).
76
How must an INS system be aligned?
Accelerometers set to zero and orientated to true north. (Gyro-compassing).
77
What is a disadvantage of a north pointing system?
It cannot be used while operating in polar regions.
78
A feature of INS is to automatically update the navigation position using DME and/or VOR information. True or False?
True.
79
What is the ideal DME update?
2 DME beacons at 90° (along and cross-track).
80
What is the distance required for an update using a co-located VOR/DME?
25nm. (Or passing overhead a single VOR/DME).
81
Advising ATC when using area navigation systems in CTA is?
3 hours (single unit). 5 hours (multiple units).
82
How do you calculate radial error?
3 + 3t (t = hours of operation in NAV mode).
83
Auto-updating is permissible within what distance using 2 DME beacons?
200nm.
84
What are the ideal properties of a map?
CERTGGC - Conformality, Equal area, Rhumb lines = straight lines, True azimuth, Great circles = straight lines, Geographic positions easily located and Constant scale.
85
What occurs between rhumb line and great circle tracks at the halfway position?
They always parallel each other.
86
What is the convergence factor formula?
Convergence (n) = bearing change / longitude change
87
What is the convergence factor formula?
Convergence (n) = bearing change / longitude change
88
What mnemonic can be used of off track problems using a triangle with one 90° angle?
SOHCAHTOA - SINA = OPP/HYP COSB = ADJ/HYP TANC = OPP/ADJ
89
360° of of longitude rotation occurs in 24 hours, how many degrees of longitude is this per hour?
15° of longitude.
90
Each degree of longitude = 4 minutes of time. True or false?
True.
91
In which direction and how fast would you need to fly to keep the sun stationary in the sky?
West at 900 knots. (15x60) (At the equator 1° of longitude = 60nm.
92
What is the formula for ETI?
ETI = Distance/Groundspeed x 60
93
When flying at a constant mach number, what is occurring to the speed of sound?
Remaining constant. Constant mach number = constant sos.
94
What does speed of sound vary with?
Temperature. (The speed of sound is faster with a higher OAT and slower with a lower OAT).
95
What is the on-track critical point formula?
Dist to CP (nm from depart.) = Total distance x GSh / GSh + GSo
96
List the steps to calculating an off-track ETP (CP)
1 - Draw the base line. 2 - Bisect the base line at right 90°. 3 - Extend bisector to current track. 4 - Calculate W/V length (distance to divert to alt/TAS x 60). 5 - Draw vector to that length terminating at the nil-wind ETP. 6 - From the origin of W/V draw a line parallel to the bisector back to original track. 7 - Find adjusted ETP.
97
How do you estimate the latest point of safe diversion (LSPD) based on NIL-WIND?
TAS x Safe endurance (mins) / 60 = MAX range distance (NIL WIND).
98
How do you calculate the distance to an NDB/VOR?
Distance to NDB/VOR = Distance flown x 60 / bearing change angle.
99
How do you calculate the TIME to PNR?
Safe endurance(mins) x GShome / GShome + GSon
100
How do you calculate the DISTANCE to PNR?
Time to PNR x GSo / 60
101
The purpose of the LOOP antenna in an ADF system is?
To locate the aural null.
102
The purpose of the SENSE antenna in an ADF system is?
To resolve the 180° ambiguity.
103
How does a horizontally polarised radio antenna transmit its electrical and magnetic elements?
Horizontal in electrical and vertical in magnetic.
104
How does a GROUNDSPEED readout change when approaching and passing overhead a DME station?
Decreases at an increasing rate until overhead and then increases at a decreasing rate.
105
How does a DISTANCE readout change when approaching and passing overhead a DME station?
Decreases at an decreasing rate until overhead and then increases at a increasing rate.
106
What is the difference between primary surveillance radar (PSR) and secondary surveillance radar (SSR)?
PSR relies on the transmitted signal being sent out and reflected by an object (aircraft). This requires a strong initial transmission.
SSR requires a much less powerful transmission signal from the ground station. The receiver in the aircraft (transponder) re-amplifies and sends back a stronger signal than what was originally received.
107
HF radio waves propagate by?
Single and multi-hop skywaves.
108
What temperature conditions cause the altimeter to over-read?
ISA (-) conditions.
109
What temperature conditions cause the altimeter to under-read?
ISA (+) conditions.
110
Calibrated Airspeed (CAS) is?
Indicated airspeed corrected for instrument and pressure errors. IAS = CAS.
111
Errors in the mach meter are?
Instrument and pressure errors.
112
Where is the flux valve located?
Remotely. (Generally in the aircraft wingtips).
113
Radar altimeters use what type of transmission and at what altitude?
Pulsed and high altitude.
114
Radio altimeters use what type of transmission and at what altitude?
Continuous wave and low level (up to 2500ft AGL).
115
What may be identified by irregularities in Wx radar returns?
Turbulence and hail activity.
116
What occurs to CAS if Mach is held constant during a climb?
CAS continuously decreases up the the tropopause. (Chicken Tikka Masala).
117
What are the known errors in the GPS system?
SITTERSG - Satellite clock error, Ionosphere, Tropopause, Total, Ephemeris error (satellite positioning), Selective availability, GDOP.
118
The most significant GPS is caused by?
The Ionosphere. (approx. around 8 metres).
119
What type of radio waves does the NDB primarily propagate?
Ground waves.
120
What does tilt error in a magnetic compass cause?
The C of G to become offset from the pivot point resulting in turning and acceleration errors.
121
What is the typical accuracy of a radar altimeter?
2-5%.
122
When may an IRS/INS system not be manually updated?
Overhead an NDB.
123
What is the formula for calculating the rough LPSD in minutes?
PP to Dest. (mins) x Safe endurance (mins) / PP to Dest (mins) + Dest. to alternate (mins).
124
What does SIN30 equal?
0.5
125
What does SIN45 equal?
0.7
126
What does SIN60 equal?
0.87
127
What does COS30 equal?
0.87
128
What does COS45 equal?
0.7
129
What does COS60 equal?
0.5
130
Wander of a gyros axis in the horizontal plane is known as?
Drift.
131
Wander of a gyros axis in the vertical plane is known as?
Topple.
132
What flight levels are isothermal (constant temperature)?
FL360 to FL660 (-56°c)
133
What happens to the PNR with wind increase/decrease?
Closer to departure/further from departure.
134
What happens to the PNR with TAS increase/decrease?
Further from departure/closer to departure.
135
What happens to the Critical Point with WIND increase/decrease?
CP moves upwind from the midpoint/moves closer to midpoint.
136
What happens to the Critical Point with TAS increase/decrease?
CP moves closer to midpoint/moves upwind from the midpoint.
137
SSR uplink frequency is?
1030Mhz (ground station to transponder).
138
SSR downlink frequency is?
1090Mhz (transponder to ground station).
139
What frequency is the outer marker modulated at?
400Hz
140
What is the main advantage of a servo assisted altimeter?
Increased accuracy at all altitudes.
141
When are manual updates of INS permitted?
Overhead a VOR or within 25nm of a co-located VOR/DME not above 5000ft.
142
What are the errors in a magnetic compass?
ONUS and SAND. (Related to compass dip. MINIMUM at magnetic equator and INCREASES with LATITUDE).
143
What does compass dip cause the with a compasses CoG?
To move away from the pivot point, inducing most errors.
144
2 separate forms of pseudo random codes exist. What are they called and what are their frequencies?
C/A (civilian) = 1575 Mhz and the P-code (military) = 1227 Mhz
