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Nav 2 Exam Flashcards

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1
Q

Definition of DME

A

Accurate slant range indicator that requires dedicated equipment both on the ground and in the aircraft.

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2
Q

What frequency does DME work in and what equipment does it need

A

UHF

Transponder (receiver responder)
Interrogator (transmitter receiver)
Distance indicator (digital or analogue)

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3
Q

How many frequencies are used for DME and why?

A

2

To avoid a/c interrogating each other

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4
Q

Why does the pulse pair of DME vary?

A

To give it’s own unique code and distinguish it from other a/c

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5
Q

How accurate is DME

A

To within 1NM

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6
Q

How many a/c interrogations can DME accept?

A

Up to 100

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7
Q

What is slant error

A

The closer to the beacon you are the less accurate the reading is

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8
Q

What equipment does an a/c need to be fitted with to use DME

A

Interrogator

Distance indicator

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9
Q

Why do we use DME

A

Enhances accuracy of holding patterns

Military use for air to air refuelling

Can be collocated with VOR and precision approach aids

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10
Q

What do VORs do

A

Give bearings by phase comparison

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11
Q

How do VORs identify themselves

A

3 letter morse code or speech

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12
Q

VOR use line of sight true or false

A

True

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13
Q

What does VOR operating range depend on?

A

A/c height

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14
Q

What are the 2 signals VOR uses and how are they transmitted

A

Reference signal transmitted omni-directionally

Variable signal transmitted by a circular range of aerials around reference signal antenna simulating a revolving antenna

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15
Q

Are the 2 VOR signals transmitted simultaneously?

A

Yes but simulated rotation causes a phase difference which varies with change of bearing

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16
Q

Where does a VOR not transmit a useable signal?

A

Vertically

This is called cone of silence or cone of confusion

Increases with height

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17
Q

What extends outwards from VOR

A

Radials

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18
Q

Benefit of VOR and a downside

A

Can Install in difficult terrain

Expensive to equip and install

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19
Q

What is QDM

A

Magnetic heading to the beacon/station (aka homing)

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20
Q

What is QDR

A

Magnetic bearing from the beacon/station

I.e radial

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21
Q

What does OBS stand for and what does it do?

A

Omni bearing selector

Instrument on A/c which shows them general heading to or from beacon and VOR info.

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22
Q

Name 4 VOR errors

A

Site error

Propagation error

Equipment error

Interference error

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23
Q

What are the approx ranges obtainable for reliable VOR ops

A

50nm at 1000ft
90nm at 5000ft
150nm at 15000ft
200nm at 25000ft

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24
Q

What is the accuracy of VOR

A

+/- 1.25 degrees

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25
How far apart are VORs spaced
50-100nm to ensure local coverage
26
What are VORs used for
Hoping to a station Flying holding pattern Maintaining track along airway centreline Obtaining a position line
27
What is interference error in VOR
Narrow operating bands limits number of channels. Huh flying a/c may receive signals from more than one VOR on same frequency To rectify VOR on same frequency must be 500nm apart
28
What is RDF
Radio direction finding The measurement of the direction from which a received signal was transmitted
29
What is a radio bearing
The angle between the apparent direction of a definite source of emission of radio waves and a reference direction as determined at DF station
30
What is a true radio bearing
Radio bearing who’s reference direction is true north
31
What is a magnetic radio bearing
A radio bearing for which the reference direction is magnetic north
32
What does DRDF stand for
Digital radio direction finding
33
what are the DF accuracy tolerance classes?
A +/- 2 degrees B +/- 5 degrees C +/- 10 degrees D worse than class C
34
What are the uses of DF for ATCOs
Can assist a pilot who is lost
35
What is QTE
Time bearing of a/c in relation to DF station or other specified point
36
What is triangulation
Pilots can establish their approx position by obtaining 2 or more bearings for separate DF stations and plotting the point the bearings intercept
37
What is homing
Using the DF equipment and radio bearing to proceed continuously towards the station.
38
When can you refuse to give DF bearing headings or position
Conditions unsatisfactory Bearings don’t fall in stations calibration limits Doing so would monopolise the frequency
39
What is an ADF? What frequency does it use
Automatic direction finder. Operates 300khz to 3mhz Fitted in an a/c
40
What is an NDB
Omni directional transmitter that operates MF 190-1750khz Average radius of cover between 10&500nm
41
When are high powered NDBs used
For long range navigation
42
When are low powered NDBs used
Airfield approach aids - locator beacons
43
What is RMI
Radio magnetic indicator - arrow superimposed onto compass rose used to read QD Can have more than 1 arrow to show multiple beacons
44
What is RBI
Relative bearing indicator Shows relative bearing in relation to a/c heading To obtain bearing to NDB - a/c heading must be added to RBI reading
45
What are the 7 NDB errors
``` 1 static interference 2 station interference 3 mountain effect 4 night effect 5 coastal refraction 6 quadrantal error 7 system malfunction ```
46
What is NDB static interference
Heavy precipitation and TS cause static. ADF needle points into TS
47
What is NDB mountain effect
LF andMF surface waves reflected by high ground - overcome by flying high
48
What is NDB coastal refraction
Radio waves travel faster over sea. Any angle except 90 degrees refracted
49
What is quadrantal error (NDB)
A/c frame reflects, refracts and re radiates incoming radio waves.
50
When are maximum and minimum NDB ranges experienced
Maximum from high power NDB at night over sea Minimum from low powered NDB at airfields
51
Advantages of NDB
Reception not limited to line of sight - follows curvature of earth Max range dependent on power of NDB
52
NDB disadvantages
Subject to atmospheric interference, coastal and night refraction which affects bearing accuracy Is not as accurate at VOR
53
ILS definition
A precision runway approach that provides accurate guidance both in azimuth and elevation
54
What are runways served by an ILS called?
Precision approach instrument runway
55
ILS uses and benefits
Pilot interpreted aid Designed for low cloud base or poor vis Assist in achieving orderly flow of landing traffic Operate continuously without assistance from ATC
56
What is a localiser transmitter
Defines extended centreline Indicates deviation from optimum lateral approach path Upwind end of rwy approx 300m from threshold
57
What is a glide path transmitter
Defines safe descent slope (usually 3 degrees) Situated 300m from landing threshold and offset between 100&200m from centreline
58
What are the marker beacons and where are they located
Installed on approach to define ranges from the threshold Outer 3-6nm from threshold Middle 900-1200m from threshold Inner 300-450m from threshold
59
What is a DME transponder and what does it do
Provides range info - used instead of marker beacons Frequently paired with localiser - DME autotunes when ILS selected Accurate only with localiser Coverage up to 25000ft Range 0 degrees at threshold
60
What does a localiser do?
Transmits a signal in the 108-112 MHz VHF band Radiates 2 lobes which overlap by 5 degrees Flight receives signals of equal intensity from both lobes when on centreline Coverage goes out to 35 degrees either side of centreline out to 17nm and thereafter at 10 degrees
61
ILS localisers provide coverage from centre of localiser antenna to distances of...
25nm within 10 degrees of course line 17nm within 35 degrees (25 degrees plus the other 10 degrees)
62
What does the glide path do?
Operates 329.3-335 MHz UHF band Radiates 2 lobes which overlap by 1 degree out to a max of 10nm Overlapping area subtends an angle of 3 degrees to give continuous descending approach to touch down point. When on correct descent path will receive signals of equal intensity
63
What is the glide path aerial also known as
ILS reference point
64
What is the glide path protected range
Out to 10nm Horizontally 8 degrees either side of centreline Vertically 0.45 x GP below surface and 1.75 x GP above
65
What do glidepath aerial locations and approach angles depend on
A/c likely to use Terrain Obstacles within approach or missed approach Local met conditions Rwy length
66
ILS reference datum
Affects location of the glide path aerial 50ft across threshold Rate of height loss depends on approach angle 2.5 degrees = 250ft per nm 3 degrees = 300ft per nm 3.5 degrees = 350ft per nm
67
Why are localiser and glidepath transmissions frequency paired
Reduces cockpit workload Guards against mismatching Only localiser frequency needs to be published
68
What does ILS automatic equipment monitor?
Radiation fields of Localiser Glidepath Markers
69
If an ILS is under maintenance or radiating due test purposes how would pilot know
Identifier removed or replaced by continuous tone
70
How does a/c identify an ILS
3 letter morse code ID on localiser carrier wave
71
What happens if ILS power drops below an acceptable level
Automatically ceases to transmit ATC and pilot warned
72
How is ILS displayed in cockpit
HSI (horizontal situation indicator) and OBS (omni directional bearing selector) Each dot indicates out by 0.5 degrees horizontal 0.15 degrees vertical
73
When will needle remain fixed on ILS cockpit display
When the RX is switched off No signal received A/c is on centreline of both loc and GP beams
74
When can pilot use auto land
A/c equipment suitable TX protected from external interference ILS sensitive area
75
What are the ILS categories and what are they based on
``` Cat 1 Lower than cat 1 Cat 2 Lower than standard cat 2 Cat 3 (a,b,c) ``` Based on rwy lights and protection from infringements
76
What is ILS cat 1
DH not lower than 200ft Vis not less than 800m OR RVR not less than 550m
77
What is ILS lower than standard cat 1
DH 200ft RVR lower than cat 1 (550m) but not lower than 400m
78
What is ILS cat 2
DH lower than 200ft RVR not less that 350m
79
What is ILS other than standard cat 2
ILS or MLS Some or all elements of cat 2 light system not available DH below 200ft but not lower than 100ft RVR not less than 350m
80
What is ILS Cat 3 A
DH lower than 100ft Or No decision height and RVR not less than 200m
81
What is ILS cat 3 B
DH Lower than 50ft Or No DH and RVR less than 200m but not less than 75m
82
What is ILS cat 3 C
Blind landings No DH no RVR limits

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