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We have seen, in previous lessons, how VOR/DME/ILS work. However, we have not yet discussed Direction Finding (1)which is one of the oldest methods of navigation. Direction finding originally was developed in the 1920s to provide a "fix" (2)on an aircraft’s position. Generally speaking, this is an emergency type of navigational device (3)which enables a controller to help a "lost" pilot find an airport by giving him headings to follow. The technique is useful on occasions in search and rescue operations to plot the location of an aircraft at an unknown position.

Direction Finder
Automatic direction finding (ADF) is an airborne counterpart (4, 5, 6)of the ground Direction Finding equipment. In an aircraft, the ADF permits a pilot to take continuous bearings automatically on any ground station operating on a frequency usable by the airborne equipment. The ground stations which are available to the pilot for this purpose include "compass locators", Non-directional Radio Beacon (7, 8)(NDB), and commercial radio-broadcasting stations. All of these may be used by the ADF-equipped aircraft for en-route navigation and for approaches to certain airports in remote areas. ADF is used mainly as a "backup" (9)navigational device, or in areas of the world where traffic is light and ground navigation aids are limited. It does not provide the position-fixing accuracy or display needed for modern air navigation in high-density (10)traffic patterns.

There are other navigational aids: Decca and LORAN (11, 12)are two of the most commonly known in aviation.




1. Direction Finding ─ A navigational aid.
2. Fix ─ Position of an aircraft as determined by various means of navigation.
3. Device ─ An instrument or equipment designed for a particular purpose.
4. ADF ─ Automatic Direction Finding. A navigational aid in the aircraft.
5. Airborne ─ An aircraft in flight is airborne. In this particular case, however, it means equipment installed in the aircraft, known as airborne equipment.
6. Counterpart ─ Equivalent.
7. Compass locators ─ Low powered radio beacons frequently installed at the same locations as outer and middle markers.
8. NDB ─ Non-directional radio beacon.
9. Backup ─ Support or help.
10. High density area ─ An area with a lot of traffic.
11. Decca ─ A navigational aid.
12. LORAN ─ A navigational aid, known as Long Range Navigation.


1. Is Direction Finding an old method of navigation? Was Direction Finding developed in the 1920s? The 1930 s? When was Direction Finding developed? Is Direction Finding still a navigational aid today? Is the technique of Direction Finding still used today? Is Direction Finding used for search and rescue operations? Is Direction Finding used to plot the location of an aircraft? Why is Direction Finding a useful method of navigation?

2. Does a navigator want a fix on his position? A pilot? A radio technician? Who wants a fix on his position? Does Direction Finding enable a pilot to get a fix on his position? VOR? DME? MTI? What enables a pilot to get a fix on his position? Is a pilot lost when he has a fix on his position? Does he call MAYDAY when he has a fix on his position? Does he need search and rescue operations when he has a fix on his position? When does he want a fix on his position? What enables a pilot to get a fix on his position?

3. Is a compass a useful device? A tachometer? A spanner? Was the wheel the first useful device ever invented? What do you consider was the first useful device ever invented? Name a useful navigational device.

4. Is ADF also a navigational aid? Is ADF in the aircraft? Can the pilot get his bearings with ADF? Can a pilot get his bearings automatically with ADF? Can a pilot get a fix on his position with ADF? Is ADF also used by controllers? Who uses ADF? Why does a pilot use ADF?

5. If ADF is in the aircraft, is it airborne? Is all equipment on the flight deck airborne equipment? Is a pilot always airborne? A stewardess? When is a pilot airborne? Why is equipment called airborne equipment? Why is ground equipment not called airborne equipment?

6. Is ADF similar equipment to Direction Finding equipment? Is ADF a useful counterpart to Direction Finding equipment? Is a windsock a useful counterpart to a wind direction indicator? Are some grammar books useful counterparts to other grammar books? Is this book a counterpart to other aviation language books? To a grammar book? What is a useful counterpart to this book? To ADF? To a windsock?

7. Is the compass locator situated at the aerodrome? Does the compass locator help the pilot get a fix on his position? Is a compass locator one of many devices enabling a pilot to get a fix on his position? Where is a compass locator situated? Is the compass locator a radio beacon? Is the compass locator a high frequency radio beacon? What sort of radio beacon is a compass locator?

8. Is NDB a non-directional radio beacon? Is NDB a useful counterpart to other navigational aids? Is NDB situated at the aerodrome? Can a pilot take his bearings from NDB? Is NDB airborne equipment? Where is NDB? What does NDB stand for?

9. Do you help friends when they are in trouble? Do you backup friends when they are in trouble? When they need you? Is ADF used as backup equipment to other navigational equipment? Why is it necessary to have backup equipment in navigation?

10. Does Chicago International Aerodrome have the highest density traffic in the world? Does Charles de Gaulle International have high density traffic? Heathrow International? What aerodrome has the highest density traffic?

11. Is Decca a navigational aid? Is Decca one of many navigational aids? Is Decca used on the North Atlantic? Pacific? Everywhere in the world? Where is Decca used?

12. Is LORAN also a navigational aid? Is LORAN a navigational aid approved by ICAO? Do pilots also approve of LORAN as a navigational aid? What does LORAN stand for?


Instructions to students: Choose the appropriate meaning, or meanings, if more than one meaning applies. Mark the square accordingly.



a) Every aircraft has, on its flight deck a) Navaid equipment can consist of
i. airborne equipment. i) LORAN.
ii. a compass. ii) Decca.
iii. a tachometer. iii) commercial radio broadcasting stations
iv. ADF.    
b) A pilot cannot navigate without   b) When approaching an aerodrome a pilot sees  
i. ICAO. i) an NDB beacon.
ii. finding his bearings. ii) an aerodrome beacon.
iii. having a fix on his position iii) a morse code signal.
iv. Decca. iv) a compass locator.
c) Search and rescue operate   c) In an emergency it is useful for a pilot to have  
i) when they receive a MAYDAY signal. i) backup equipment.
ii) when they receive a distress signal. ii) Direction Finding equipment.
iii) in an emergency. iii) high density fog
iv) with Direction Finding equipment. iv) a fix on his position.
d) With Direction Finding equipment a controller can   d) Some airborne equipment is  
i) vector a pilot into position. i) ADF.
ii) help a pilot who is lost. ii) ILS.
iii) give a pilot headings to follow. iii) VASIS.
iv) direct an aircraft through high density traffic. iv) a transponder.


Instructions to students: Describe in your own words the functions of the following, distinguishing between a navaid and a landing aid:







A Distance Measuring Equipment (DME) (8)
aboard (1) domestic flights (6)
advice (3) downwind leg (4)
advise, to (3) E
aerodrome beacon (12) echo (13)
Aerodrome Surveillance Radar (ASR) (13) effect (3)
Aeronautical Information Publication elevation of aerodrome (2)
(AIP) (2) emergency procedures (1)
affect, to (3) Enroute Surveillance Radar (RSR) (13)
airborne (15) Expected Approach Time (EAT) (5)
aircraft identification (7) Expected Time of Arrival (ETA) (10)
airway (2) F
aldis lamp (4) facilities (2)
align, to (12) fan marker (9)
alternate aerodrome (2) fasten, to (1)
altimeter setting indicator(4) filed true airspeed (7)
area of high pressure (3) final approach (4)
area of low pressure (3) fix (10) (15)
automatic data processing (14) flashes (12)
Automatic Direction Finding(ADF) (15) flexibility (14)
Automatic Terminal Information Service flight attendant (1)
(ATIS) (4) flight level (1)
B flight plan (2)
back-up (15) flight progress board (7)
barometer (10) flight progress strips (7)
base leg (4) front (3)
beam (9) full-load (10)
bearing (8) functions (7)
briefing officer (2) G
C glide path equipment (9)
Cathode Ray Tube (CRT) (13) go ahead (1)
ceiling (3) Ground Control Approach (GCA) (13)
centre line (2) ground speed (3)
Circular Polarization (14) H
clearance (1) hazardous (14)
clear of runway (1) heading (1)
clutter (14) headset (4)
cold front (3) headwind (3)
compass locators (15) hectic (10)
computer (7) high density area (15)
console (4) high pressure area (3)
contact, to (1) holding pattern (10)
co-ordinate, to (5) holding point (6)
counterpart (15) holding position (I)
current flight data (7) home-on, to (10)
current weather conditions (3) I
cut engines, to (12) inbound (10)
cruising speed (2) identification beacon (12)
D illuminate, to (12)
Decca (15) inner marker (9)
deficiencies (14) Instrument Flight Rules (IFR) (2)
device (15) Instrument Landing System (ILS) (9)
dew point (10) Instrument Landing System indicator (9)
direction finding (15) Instrument Meteorological Conditions
Note: () Indicates Lesson Number  
(IMC) (3) restricted area (4)
intercept, to (10) revert back, to (6)
interference (8) revolutions per minute (rpm) (13)
international airport (6) roger (1)
International Civil Aviation rotate, to (12)
Organization (ICAO) (9) routine (7)
intensity (12) runway edge (12)
interrogator (8) runway in use (4) light gun (4)
knots (10) scanner (13)
L Secondary Surveillance Radar (SSR) (13)
landing sequence (4) sector (7)
lateral separation (7) signalling lamp (4)
local flights (10) slashes (14)
localizer (9) specify, to (7)
longitudinal separation (7) spread, to (10)
long range radar (13) stack, to (5)
Loran (15) static (8)
loudspeaker (4) stray, to (2)
low pressure area (3) subsonic aircraft (6)
M supersonic aircraft (6)
maintain, to (1) synoptic chart (3) middle marker (9)
manoeuvre, to (4) T
manually (7) tailwind (3)
marshaller (12) target (13)
meteorologist (3) Terminal Area Surveillance Radar (TAR) (13)
microphone (4) threshold (9)
morse code (12) tower cab (4)
Moving Target Indicator (MTI) (14) track, to (13)
N traffic circuit (4)
nautical miles (8) transponder (8)
navaids (8) true airspeed (7)
Non-Directional Radio Beacon (NDB) (15) tune in to, to (1)
Notices to Airmen (NOTAM) (2) type of aircraft (6)
observe, to (1) Ultra High Frequency (UHF) (5)
outbound (10) unaware of (1)
outer marker (9) V
over (1) vector, to (10)
overcast (3) vertical separation (7)
overlap (14) Very High Frequency (VHF) (5)
overshoot (9) Very High Frequency Omni directional Range
P (V0R) (8)
precipitation (3) Visual Approach Slope Indicator System
precise (9) (VASIS) (12)
Precision Approach Radar (PAR) (13) Visual Flight Rules (VFR) (2)
primary radar (13) Visual Meteorological Conditions (VMC) (5)
procedure turn (10) W
pulse (13) wake turbulence (10)
R wand (12)
radials (8) warm front (3)
radio navigation aids (navaids) (8) weather forecast (3)
ramp (1) wind direction indicator (4)
reading (8) wind speed indicator (4)
reflect, to (13) workload (7)
relay, to (1)  
reporting points (2)  


Course 291






Date: 2015-12-11; view: 1645

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