1
Q
What are the three primary qualities of wave energy and in what way are two are linked?
A
Wavelength. Amplitude. Frequency. Wavelength and frequency are linked, the shorter the wavelength the higher the frequency.
2
Q
What can the propagation of electromagnetic waves be affected by?
A
Reflection. Refraction. Diffraction. Attenuation.
3
Q
What can the propagation of electromagnetic waves be affected by?
A
Reflection. Refraction. Diffraction. Attenuation
4
Q
What effect reduces signal strength and limits range of radio signals due to Obstructions, Absorption (water vapour) and Dust particles?
A
Attenuation
5
Q
What phenomenon causes waves to bend around or over obstructions (Mountains etc)?
A
Diffraction
6
Q
What effect is caused by a change in velocity as an electromagnetic wave passes from one medium to another (of differing density)?
A
Refraction
7
Q
What is reflection?
A
Reflection is when the angle of incidence is equal to the angle of reflection.
8
Q
Which two atmospheric variables can affect the refraction of EM waves? Which atmospheric variable, on its own, has no effect on EM waves?
A
Moisture and Low temperature.
Pressure has no effect on EM waves.
9
Q
What are the three principle paths of propagation that EM waves may follow between a transmitter and receiver?
A
Surface wave, Sky wave, Space wave
10
Q
What occurs when radar or radio waves get trapped between a layer of cold air and the earth’s surface or in a layer of warm air between two layers of cold air, leading to performance anomalies?
A
Ducting
11
Q
What is the free space velocity of electromagnetic waves in metres per second?
A
3 × 10 metres per sec
(186,000 miles per sec or 162,000 nm per sec)
12
Q
What are the common terms of magnitude used for communications and radar frequencies with the following values:
a. H2 × 10 3
b: H2 x 10 6
c. H2 x 10 9
A
A. Kilohertz (KHz)
B. Megahertz (MHz)
C. Gigahertz (GHz)
13
Q
How would 3000MHz be expressed in GHz?
A
3GHz
14
Q
How would 2000kHz be expressed in MHZ?
A
2 MHz
15
Q
How would 10Ghz be expressed in MHZ?
A
10,000 MHZ
16
Q
Which frequency band in the radio spectrum is between 3-30MHZ?
A
High Frequency (HF)
17
Q
Which frequency band in the radio spectrum is between 30-300MHZ?
A
Very High Frequency (VHF)
18
Q
Which frequency band in the radio spectrum is between 300-3000MHz?
A
Ultra High Frequency (UHF)
19
Q
Radio waves can pass through opaque bodies such as buildings, cloud and rain but what may happen to them in doing so and what is this dependent on?
A
They suffer attenuation which is dependent on the frequency (more attenuation at higher frequencies) and also the amplitude (signal strength) of the transmitted signal.
20
Q
What are the 2 fields of a radio wave and how are they orientated to each other?
A
- Electric
- magnetic fields
90 degrees to each other
21
Q
In the graphic below, what is the method of radio propagation depicted at A, B and C?
A
A - Sky wave
B - Surface Wave
C - Space Wave
22
Q
In the graphic above, which frequency bands use the propagation path at B and what military platform may use this type of communication path?
A
VLF, LF and MF (to some extent). Submarines sometimes make use of this communication path.
23
Q
In the graphic above, what is causing the propagation of signal path A and what communication frequency band makes use of this to achieve long range point to point communication?
A
Signal path A (sky wave) is being refracted by the ionosphere to achieve long range communications and the HF frequency band can exploit this type of propagation.
24
Q
In the graphic below, what are the two factors that can affect the different propagation paths shown?
A
- Angle of incidence of the transmitted signal
- frequency used.
25
In the graphic below, what is the term for the distance (A) between the transmitter and receiver which has been achieved by the signal propagation path shown and what is the term for the area (B) where the ground wave can no longer propagate?
A = Skip distance,
B = Dead space.
26
In the graphic below which signal from A, B and C is the maximum usable frequency the higher than maximum usable frequency and the lower than maximum usable frequency.
A – higher than Max usable frequency
B – lower than Max usable frequency
C – Max usable frequency
27
What type of radio signal propagation is shown in the graphic below and which communications frequency bands use this?
- Space wave (line of Sight)
- used by VHF and UHF radio communications
28
In space wave or line of site signal propagation the theoretical transmission – reception distance is limited by the geometric Horizon (does the transmitting antenna have a direct line of site to the receiving antenna) however due to the refractive properties of the atmosphere space waves can actually travel further. What is the term for this propagation distance and how much grade is it than the geometric Horizon.
The radio horizon which is about 15% greater than the geometric horizon
29
Apart from radio communications, what other aircraft avionics or sensor systems use Space wave propagation?
Radan, SATCOM, radio relay and navigation approach aids such as VOR ILS/DME TACAN and GPS
30
What is the term for the reduction in signal strength in radio signal propagation caused by obstructions, water vapour droplets and dust particles?
Attenuation
31
What effect is the obstacle in the graphic below having on the transmitted signal and what factors affect how Significant the is?
Diffraction, the amount of diffraction is related to how well the wavelength matches the size of the obstacle or gap through which the signal must pass
32
What is the term for the effect on radio signal propagation caused by a change of velocity of the EM wave as it passes from a medium of a certain density to a medium of another density causing a change in direction of the wave?
Refraction
33
Which communications frequency band(s) can be limited by noise contamination and static from the
HF
34
Which communications frequency band(s) can have a limited operating range due to line of sight transmission where power has little effect to offset this and how can an aircraft increase the line of sight/transmission range?
V/UHF frequencies and the higher an aircraft flies, the greater the line of sight range will be
35
What type of communication channel is provided by twisted pair cables, co-axial cable or fibre optic cable?
Guided wave channels
36
What type of communication channel are radio waves, microwaves and infrared waves?
Unguided wave channels.
37
In the graphic below, identify the components A, B, C and D as either a transducer, modulation and power amplification, demodulation.
A - Transducer
B - Modulation and Power Amplification
C - Demodulation,
D - Transducer
38
What are the physical dimensions of the aerials antennas in a radio or radar system related to in respect of the signal parameters?
The wavelength (hence also the frequency) of the signals they need to transmit and receive.
39
What channel spacing is used in the VHF ATC radio communication band and in the UHF radio communication band?
8.33kHz = VHF band
25kHz = UHF band.
40
What is the feature in a radio receiver which aims to provide a constant receiver signal strength output irrespective of the range in the transmission path?
Automatic Gain Control (AGC).
41
In relation to the graphic above, what is the main difference between the groundcrew/auxiliary jack boxes and the aircrew station boxes in terms of connection and access to other components of the System?
Only aircrew station boxes can connect and access the HE, VHF and UHF radios and listen to Nav Aids whereas groundcrew and auxiliary jack boxes cannot and are only connected to the aircraft internal intercom.
42
In the graphic of an air cruise station box below what is the function of the controls highlighted as A, B, C and D?
A – control to select radio for transmitting
B - pressed to transmit (PTT) switch, push radio to transmit on the radio selected on control a push INT, to transmit on the aircraft intercom.
C – controls to select listen only for each aircraft radio and to control volume of received transmissions
D - NOR position requires the PTT switch to be pushed to transmit on intercom and hot mic bypasses the PTT switch as the users microphone is constantly live on the intercom circuit.
43
What is the intercom discipline required for switching off intercom audio, removing the headset or leaving your crew station?
Inform other crew members you will be off intercom
44
In intercom discipline, what should a crew member 'A' do to initiate an exchange with another crew member 'B'?
Crew member A should nominate address crew member B by their crew position, state what crew position they are and wait to hear crew member B acknowledges the call before passing any message. Eg Radar - Pilot "Pilot - Radar, go ahead"
45
What is the difference between Primary and Secondary radar systems?
Primary Radar - A primary radar system depends on receiving a radar echo reflected passively by a target.
Secondary Radar - A transmitted radar Signal is used to trigger a response from equipment in the target.
46
What is the civilian name for a secondary radar system?
Secondary Survelllance Radar (SSR)
47
What is the military name for a secondary radar system?
Identification Friend or Foe (IFF)
48
Air Traffic Control (ATC) are able to identify and detect an aircraft but what other piece of information are they able to obtain from the aircraft's transponder if Mode Charlie is selected?
Altitude
49
Which mode was introduced to support the automation of some ATC functions?
Mode S
50
How does Mode S remove the possibility of Fruiting and Garbling?
By using the aircraft unique identifier after the all call to interrogate
51
What system is Mode S a required component of?
Traffic Alert and Collision Avoidance System TCAS
52
What are the four benefits of an Airborne Collision Avoidance System (ACAS)?
Collision avoidance protection
Airspace situational awarenes
ACAS operates between aircraft and is independent of ATC
Enhanced Safety
53
What are the military IFF Modes and which one cannot be adjusted in the cockpit?
Modes 1, 2, 3 & 5
Mode 2 Cannot be adjusted in the cockpit.
54
Which civilian modes do the military also use?
Modes A, C and S
55
Which civilian mode and military mode are the same?
Mode 3 & A
56
Which mode can ATC use to rapidly detect a specific aircraft on their radar display.
Ident
57
What are the 3 IFP emergency codes and what do they mean?
7700 - General Emergency
7600 - Comms Fail
7500 - Aircraft subject to unlawful interference (Hijack)
58
Which SSR Mode is a form of Data Link?
Mode S
59
What is the definition of a Data Link?
An automatic digital means of passing data between two or more units at an agreed speed and in a structured format over a common medium
60
What is the correct meaning of the proword 'Roger' in established aviation English?
A have received all your last transmission
61
What is the usual format for transmitting time?
Co-ordinated Universal Time (UTC)
62
What is the purpose of the military broadcast 'SECURITÉ SECURITÉ SECURITE'?
To inform all aircraft that a message contains information affecting safety
63
What techniques enable the operator to transmit clearly and satisfactorily on the radio?
Use normal conversation tone. Listen out to avoid interfering with another station. Use standard RTF words and phrases wherever possible
64
What aviation publication is the master reference for aviation RT/Comms Procedures?
CAP 413
65
What is the state of emergency when there is a safety concern for the aircraft, other vehicle or person on board or within sight, but immediate assistance is not required. What is RT prefix call in this Situation?
Urgency and the RT prefix call is PAN PAN, PAN PAN, PAN PAN
66
What is the correct meaning of the word Wilco' in established aviation English?
I understand your message and will comply with it
67
How would you conduct a radio check and what are the 5 readability meanings?
Aircraft:
Aeronautical callsign
Aircraft identification
Radio check
On frequency..
Aeronautical station:
Aircraft identification
Aeronautical callsign
Readability (1-5)
Any additional information
Readability Scale:
1 - Unreadable
2 - Readable now and then
3 - Readable, but with difficulty
4 - Readable
5 - Perfectly readable
68
What are the only 3 elements that can be transmitted in an aviation RT message?
Clearances, Instructions and Information
69
Which is the correct RT phraseology for FL 150 - "Flight Level One Fifty" or Flight Level One Five Zero?
Flight Level One Five Zero
70
What is the correct RT phraseology for a request to descend to 2500ft on a QNH pressure setting?
A - request descent altitude to twenty five hundred feet.
B - request descent to altitude two thousand five hundred feet
C - request descent to two thousand five hundered feet
D - request descent to two five zero zero
B. Request descent to altitude two thousand five hundred feet.
71
What proword would be used during a message transmission when the sender realises the message is incorrect and they indicate to the receiver to ignore what has been said?
Disregard
72
When a pilot is instructed to call another ATC unit but the details of the aircraft have not been passed to the next unit, which proword precedes the callsign of the next ATC unit in the instruction given?
Freecall (e.g. "Freecall Scottish Control on 126.055")
73
What pro word is used by ATC to make an aircraft stop taxing before a particular location?
Hold (e.g “Hold short of taxiways Charlie 1 and Delta 2 intersection”)
74
What proword is used as an instruction to listen out on a particular frequency?
Monitor
75
What proword would be used if a pilot wanted to say “I am not capable of flying at 140 kts”
Unable speed 140kts or Negative speed 140kts
76
What proword would be used at the end of a transmission when no response is expected?
Out
77
When is the proword 'Recleared' used?
By ATC to an aircraft in relation to amended route clearances and NOT for climb/descent clearances.
78
What proword is used for "I should like to know" or wish to obtain?
Request
79
What prowords are used to ask for a repeat of all or the part af a transmission not fully received?
Say again
80
What proword means "I cannot comply with your request, Instruction or clearance"?
Unable
81
What is the aeronautical station callsign suffix for aerodrome control?
Tower
82
What is the aeronautical station callsign suffix for control of taxying aircraft?
Ground
83
What is the aeronautical station callsign suffix for a MATZ crossing clearancer
Zone
84
What is the aeronautical station callsign suffix for a Precision Approach Radar instrument approach
Talk down
85
What is the aeronautical station callsign suffix far an Air/Ground Communication Service?
Radio
86
What clearances or instructions CANNOT be relayed by a Clearance Delivery aeronautical station?
Start clearance, pushback, taxy clearance or take off clearance
87
After an aircraft or aeronautical station makes an initial call, how long should elapse before a second call is made it no reply to the first call is received?
10 seconds
88
What are the VHF and UHF emergency frequencies?
VHF is 121.500 MHz and UHF is 243.000 MHz
89
If a pilot is in radio contact with an ATC agency and an emergency occurs, what frequency should be used for the emergency call and message?
The frequency currently in use
90
How is the state of emergency "DISTRESS" defined and what is the RT prefix call in the emergency message?
Threatened by serious or imminent danger requiring immediate assistance and the RT prefix call is "MAYDAY, MAYDAY, MAYDAY".
91
What details should be contained in the emergency message?
Aeronautical Station addressed callsign
Aircraft callsign
Type of aircraft
Nature of emergency
Intentions of the captain and assistance required
Position of the aircraft
Level of the aircraft
Heading
(and if relevant, plot qualifications and any other information).
92
What is the purpose of the ground marshaller?
To ensure the aircraft is manoeuvred safely on the ground.
93
Who is ultimately responsible for the safety of the aircraft whilst manoeuvring on the ground?
The aircraft commander.
94
What are your considerations should you lose sight of the marshaller?
Bring the aircraft to a stop and then seek further assistance.
95
What is the recognised marshalling signal for an engine fire?
Pointing to the source of fire and drawing a figure of eight with your other arm.
96
What is the recognised marshalling signal for cutting an engine?
To swipe a flat hand across the front of your neck.
97
What is the recognised marshalling signal for affirmative?
The Thumbs up signal.
98
What is the recognised marshalling signal for stop?
Crossed arms above your head.
99
What is the recognised marshalling signal for this way?
Arms above the head in a vertical position with palms facing inward.
100
If there are obstructions and/or the aircraft is large with restricted view from the cockpit/flight deck, what additional measures should be considered?
The use of 2 extra marshalling personnel to act as wing walkers who signal to the pilot if there is enough room for the aircraft to pass safely.
101
Match the following electronic warfare definition extracts numbered 1 to 4 to the descriptors A, B, C, and D.
1. Involves all actions taken to protect personnel facilities and equipment from any effects of friendly or enemy employment of electronic warfare degrades neutralise or destroy friendly combat capability.
2. Used to intercept identify and locate sources of intentional and unintentional radiated EM energy.
3. Encompasses any military action that involves the use or control of the electromagnetic spectrum EM to produce or prevent hostile use by or to attack an enemy.
4. Hugh EM energy with the intent of degrading neutralising or destroying combat capability and actions to prevent or reduce the enemies effective use of EM spectrum such as jamming and deception.
A – electronic support
B – electronic attack
C – electronic warfare
D – electronic defence
1 - ED
2 - ES
3 - EW
4 - EA
102
In the graphic below, what are the forms of EM waves labelled A – G?
A = radio waves
B = Microwaves
C = infra - red
D = ultraviolet
E = X-Rays
F = Gamma
G = Cosmic
103
What is depicted in the graphic below?
A communications control system (CCS)
104
What are the labelled components of the IFF/SSR System?
A - Transponder
B - Interrogator
C - Synchroniser
D - Primary Radar
105
What frequency does the Interrogator transmit on?
1030 MHz
106
What frequency does the transponder reply on?
1090 MHz
107
What does a transponder provide ATC with?
An automatic means of communication
108
What four things can cause SSR information to become degraded or inaccurate?
Fruiting
Garbling
Sidelobe Signals
Transponder Suppression
109
In relation to the above, what occurs when the interrogating station receives replies from transponders replying to other ground stations?
Fruiting
110
If aircraft are too close together when interrogated, what can happen?
Garbling.
111
What EW equipment is used to detect, localise and identify threat radars?
A Radar Warning Receiver (RWR)
112
What is the benefit that the equipment in Question 2 has over threat radars it is detecting and why does this occur?
The benefit is called Range Advantage and occurs because the threat radar has to detect an echo from a target that is subject to a 2-way propagation path whereas the sensor detecting the threat radar receives a stronger signal that is only subject to a 1-way propagation path.
113
What are 2 methods of direction finding that can be used by the equipment in Question 2 and which is the most accurate?
Amplitude comparison and phase comparison of the signal being received on two or more adjacent antennas. Phase comparison is the most accurate.
114
Which parameters of a threat radar does an ECM jamming signal have to match in order to be effective?
The ECM signal has to match the RF, PRF, pulse width, scan rate and have sufficient bandwidth and have a high jammer (ECM) to victim signal ratio.
115
When a radar is subject to noise jamming, the range of the jamming platform is masked to the radar but what positional information about the jammer is still apparent?
The azimuth or bearing of the jamming platform.
116
Name 2 of the 4 main categories of radar noise jammers.
Spot jammers, sweep jammers, barrage jammers and search-lock jammers.
117
Deception ECM is generally used in self-protection jamming applications against weapon systems using fire control radars. What are they trying to degrade or deny to such a tracking radar?
Range, velocity or angle tracking
118
What type of ECM is shown in this media?
Expendable decoys, specifically EADs (expendable active decoys) which create deception by simulating a genuine radar target
119
What type of ECM is shown in this media? What is it used as a countermeasure against and why is it cut to different lengths in the cartridges?
The ECM is Chaff which is used against threat radars to create masking or deception. It is cut to different lengths match the various wavelengths/frequencies of the radars it could be used against.
120
What is the fundamental EW parameter for an aircraft that defines how 'stealthy' it is in avoiding detection by radar?
Radar Cross Section (RCS)
121
What factors affect the value of the parameter which reduces radar cross section
Aircraft size, shape, build materials and aspect or orientation to the radar.
122
State the design and build measures used to reduce the radar cross section
Incorporating resonant small components on the fuselage into a smooth blended structure. Reducing 90 degree corners on the aircraft, internal carriage of weapons and other stores, sloped vertical stabilisers, swept wings and tailplanes, coating cockpit canopies with a thin metallic film, masking engine LP compressor/fan and covering the aircraft with radar absorbent material.
123
What type of anti-aircraft missile is shown here?
This anti-aircraft missile is a 'MANPADS' (man-portable air defence system). It is a passive infra-red homing missile and the signature it uses to home and guide on comes from the jet pipe hot metal of the target, the engine(s) exhaust plume and kinetic heating of the aircraft leading edges.
124
What Electronic Support equipment can enable an aircraft to detect an IR missile and how does this sensor achieve that detection?
A Missile Warning System (MWS) can detect a MANPADS, it achieves this by detecting the UV or IR signature of the rocket motor plume produced at the moment of firing of the MANPADS.
125
What IR signature reduction measures are helicopters particularly suited for?
The placement of shrouds over their engine exhausts or upwards directed exhausts to disperse the exhaust into the rotor blades.
126
What type of jet engine helps to overcome exhaust plume IR signature?
The high-bypass turbofan engine.
127
What are the 3 types of countermeasures to passive IR homing missiles?
IR flares, IR jammers and DIRCMs.
128
What type of sensor is shown in this media?
MWS (missile warning system).
129
What is a disadvantage of earlier, omnidirectional or sector radiating IR jammers?
The power of the jammer is spread over a wide area giving a low Jammer to Signal ratio and so they only work against first generation missile seekers.
130
What type of counter measure system is shown in this media and why is it more effective than earlier systems that have the same aim? What air platforms are not suitable for this system?
DIRCM (directed infrared counter measure)
It uses a highly directional laser IR jammer which achieves a high jammer to signal ratio and so is capable of defeating up to 4" generation IR missile seekers. Fast jet aircraft are not yet suited to this system due to weight, bulkiness and drag penalties.
131
Which part(s) of the EM spectrum are concerned with electro-optical countermeasures?
Infrared and visible light.
132
What are possible countermeasures to electro-optical sensors and weapon targeting systems?
Contrast reduction/camouflage, decoys, obscuration (cloud, haze, fog or smoke), lasers and tactics.
133
What are the 3 countermeasures to laser targeting systems?
Absorption, reflection, ablation and jamming.
134
What measures can be used as Electronic Defence?
Planning, frequency allocation, SOPs and comms authentication procedures, parallel operations, equipment design, frequency agility, spread spectrum techniques and tactics.
135
What are the 3 main Electronic Support Measures systems that are part of a fully integrated Defensive Aids Suite (DAS)?
RWR, MWS and LWR.
136
What are the 3 main components of a DAS used by the pilot in the cockpit?
Control panel, threat display and countermeasures controller/activation.
137
Which components of a DAS are countermeasures?
Chaff launchers, flare launchers, towed radar decoys, radar ECM pods (and on larger aircraft DIRCMs).
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