ILS Flight Reference

Question 1

Localiser Power Density

Answer 1

CAT I: -107dBW/m²
CAT II + CAT III: -106dBW/m²

(Annex 10 - P38 3.1.3.3.2.1)

Question 2

Glide Path Power Density

Answer 2

-95dBW/m²

(Annex 10 - P49 3.1.5.3.2)

Question 3

Minimum Terrastar Accuracy

Answer 3

50mm

(FIP 201)

Question 4

6NM Profile 04 distances and heights

Profile can be adjusted to these distances and heights if weather or terrain affects the flyability

Answer 4

5NM, 1300ft
6NM, 1500ft
7NM, 1800ft
8NM, 2000ft

Question 5

Where to quit a Profile 14

Answer 5

Periodic: When the DDM passes through 0 after peaking above 1.75θ
Commissioning: 0NM

Question 6

Nominal SDM for LOC and GP

Answer 6

LOC: 40%
GP: 80%

Question 7

Standard heights and ranges for a top (Profile 12) and bottom (Profile 13) edge on a nominal 3° GP

Answer 7

Top edge (Profile 12): 6NM (4NM + 2NM) to Point B (0.5NM), 1800ft descending
Bottom edge (Profile 13): 6NM (4NM + 2NM) to Point B (0.5NM), 1400ft descending

Height may change for an abnormal GP angle, distances will remain the same

Question 8

DME range error tolerance associated with precision approach

Answer 8

Periodic: ±0.1NM
Commissing: ±0.03NM

Question 9

GP width in µA

“Width” in this case refers to half sector width and is what we use when we refer to width in a normal calibration.

Answer 9

150µA

(75µA either side)

Full sector width is double this at 300µA and is rarely used or referred to.

Question 10

LOC width in µA

Answer 10

300µA

(150µA either side)

Question 11

Usual cause if ILS is not “IDENT”ing

Answer 11

The ILS is likely in maintenance mode, usually when alarms are being checked. Before the end of the calibration the IDENT must be checked. The engineers can switch back to local mode when alarms are not being run.

Question 12

Incorrect date and time on FIS PC

Answer 12

Set the time and date manually before the start of the calibration in the Windows settings.

Question 13

Point R Calculation

Answer 13

Use WGS. Place THR coords in “Origin” and use LOC angle (or runway heading if no LOC angle) in “Azimuth” with 286m in “Dist”. New coords will be Point R.

Question 14

LOC Width Calculation

Answer 14

LOC width° = (tan^-1 (105m / LOC to THR dist(m))) x 2
If over 6°, add 1050m to LOC to THR (Point B)

Question 15

GP Width Calculation

“Width” in this case refers to half sector width and is what we use when we refer to width in a normal calibration.

Answer 15

0.24 x GP angle

Question 16

Profile 14 Start Distance Calculation

Answer 16

Slice distance (/6076 for NM) = height (ft) / tan (0.30Θ*)

Use 0.45Θ if distance for 0.30Θ falls outside DOC

Question 17

Profile 04 Start Distance Calculation

Answer 17

04 distance (/6076 for NM) = height (ft) / tan (2.35)

2.35° is a standard value and does not change with GP angle

Question 18

Symmetry Calculation

Answer 18

GP symmetry = (top edge - angle) / width
LOC symmetry = (left edge - angle) / width