Chapter 6 ILS

Question 1

What does the ILS provide guidance in?

Answer 1

Vertical (azimuth) and horizontal

Question 2

What are ILSs paired with?

Answer 2

DME

Question 3

What provides range on ILSs?

Answer 3

Marker beacons or DME

Question 4

What are the frequencies for a localiser and how many channels are there?

Answer 4

108.1-111.95MHz and 40 channels

Odd numbers only

Question 5

What are the frequencies for the glide path?

Answer 5

328.6-335.4MHz (tune to LOC frequency and GP frequency is paired with it)

Question 6

What airborne equipment is required for ILS?

Answer 6

Antenna and receiver

Question 7

What does each dot represent on a CDI when tuned to an ILS?

Answer 7

0.5 degrees

Question 8

On an HSI what is the degree per dot on the vertical scale?

Answer 8

0.7 degrees

Question 9

What are the two signals emitted by the localiser?

Answer 9

When looking towards the runway on landing:

• 150Hz on the right
• 90Hz on the left

(Lateral lobes are opposite)

Question 10

Where is the localiser protection zone?

Answer 10

35 degrees either side of the runway extended centreline and extends out to 17nm

Question 11

Describe the location of the inner protection zone

Answer 11

10 degrees either side of extended centreline and extends to 25nm

Question 12

What is the principle of operation of an ILS?

Answer 12

Depth of modulation

Question 13

What is the max height coverage of an ILS?

Answer 13

6000ft

Question 14

Where is the antenna location?

Answer 14

300m beyond landing runway threshold and 120m to side of centreline

Question 15

What frequency is the glidepath?

Answer 15

UHF (328.6Mhz - 335.4Mhz)

Question 16

What are the locations of the 90Hz and 150Hz lobes on the glidepath?

Answer 16

90Hz = above
150Hz = below

Question 17

What is the lateral coverage of the ILS?

Answer 17

8 degrees either side of the extended centreline

Question 18

What is the max number of marker beacons on the ILS?

Answer 18

3

Question 19

What is the frequency of each marker beacon?

Answer 19

Inner = 3000Hz
Middle = 1300Hz
Outer = 400Hz

Question 20

What colour light does the outer marker illuminate?

Answer 20

Blue light

Question 21

What colour light does the middle marker illuminate?

Answer 21

Amber

Question 22

What colour light does the inner marker illuminate?

Answer 22

White

Question 23

What is the vertical range of a marker beacon?

Answer 23

6000ft

Question 24

What is the range of each marker from the threshold?

Answer 24

Inner = 75-150m
Middle = 1050m (+/-150m)
Outer = 6.5-11.1km

Question 25

When flying a back beam approach how can you use the OBI?

Answer 25

You can’t (acts in reverse sense)

Question 26

How can you use the HSI when flying on the back beam?

Answer 26

Setting the course to QDM gives correct indications

Question 27

What is the formula for ROD required on a glideslope?

Answer 27

ROD = ((glidepath angle / ground speed) / 60) * 100

Question 28

What is the formula for height passing?

Answer 28

Height passing = glidepath angle * range from touchdown * 100

Question 29

What is monitoring accuracy of the localiser for each category?

Answer 29

1 = 35ft for 6 seconds
2 = 25ft for 2 seconds
3 = 10ft for 2 seconds

Question 30

What is the monitoring accuracy of the glidepath?

Answer 30

Angle change by 0.075 degrees and/or reduction in power exceeds 50%

Question 31

If a fault is detected what will the system do?

Answer 31

• remove morse code
• cease transmission
• display warning to ATC
• CAT 2 or 3 may allow degrade to a lower category

Question 32

What are the errors associated with ILS?

Answer 32

• bent beam

- scalloping

Question 33

What is the critical area?

Answer 33

An area defined where all vehicles and aircraft are excluded during all ILS operations

Question 34

What is the sensitive area?

Answer 34

An area beyond the critical area where parking and movement of vehicles is strictly controlled during low vis ops