ACFT - Navigational Instruments

Question 1

What Navigational Instruments are available to a Pilot? (6)

Answer 1

1. ADF - Automatic Direction Finder
2. NDB - Non-Directional Beacon
3. VOR - VHF Omni-directional Radio Range
4. DME - Distance Measuring Equipment
5. TACAN - Tactical Air Navigation (Military)
6. ILS - Instrument Landing System

Question 2

What is ADF? (2)

Answer 2

ADF - Automatic Direction Finder

• An on-board item of equipment used in conjunction with NDBs on the ground to provide aid for aircraft navigation
• Indicates the relative bearing of the station tuned (NDB) and/or its QDM / QDR in the cockpit

Question 3

What is an RBI? (2)

Answer 3

RBI - Relative Bearing Indicator

Consists of an arrow and a compass rose in a full circle

Question 4

What errors may occur with ADF? (8)

Answer 4

1. Errors and abnormal indications
2. Designated operational coverage
3. Mountain effect
4. Static interference
5. Station Interference - LF / MF band congestion
6. Coastal refractions
7. Lack of failure warning system
8. Night effect

Question 5

What is VOR? (5)

Answer 5

VOR - VHF Omni-directional Radio Range

• Provides a radial the aircraft is on
• CDI: Course Deviation Indicator
• RMI: Relative magnetic Indicator
• OBS - Omni-Bearing Selector

Question 6

What errors may occur with VOR? (4)

Answer 6

• Site error (±1°)
• Propagation error
• Aircraft Equipment error (±1°)
• Maximum aggregate error: ±5°

”SPAM”

Question 7

What is a TACAN? (3)

Answer 7

TACAN - Tactical Air Navigation (Military)

• Frequency band: 960-1215 Mhz
• Two-frequency principle: 15Hz & 135Hz

Question 8

What is VORTAC? (1)

Answer 8

TACAN equipped with an additional civil VOR Beacon

Question 9

What is DME? (4)

Answer 9

DME - Distance Measuring Equipment

• Working on elapsed time between two signals
• Very narrow pulses
• 1000Mhz frequency

Question 10

What are the Advantages of DME? (3)

Answer 10

1. VOR/DME installation can be used to make an Instrument Approach to an airfield
2. Calculate Groundspeed
3. A very accurate ‘fix’ can be obtained using two DME stations

Question 11

What is the Disadvantage of DME? (1)

Answer 11

Slant Range

Question 12

What are the Components of an ILS? (4)

Answer 12

1. Localiser
2. Glide path
3. Outer marker
4. Approach Lighting System

Question 13

What Categories can an ILS have? (3)

Answer 13

1. CAT I - DH of not less than 200ft
2. CAT II - DH of not less than 100ft
3. CAT III - No DH (Touchdown able)

Question 14

What frequency bands does the ILS operate? (2)

Answer 14

1. Localiser: 108.10 - 111.95 Mhz) VHF
2. Glidepath: 329.30 - 335.00 Mhz) UHF

Question 15

What are the Advantages of ILS? (3)

Answer 15

1. Pilot interpreted
2. Precision approach
3. Can be auto-piloted

Question 16

What are the Disadvantages of ILS? (3)

Answer 16

1. Subject to interference from other A/C
2. Reflections from ground facilities
3. Shortage of frequencies

Question 17

What is MLS? (1)

Answer 17

An ILS using Microwaves