Microwave Landing System - Ch 7 Flashcards Preview

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Flashcards in Microwave Landing System - Ch 7 Deck (11):
1

Precision Instruments

Needs Azimuth (lateral), Elevation, Range

2

Non - Precision

Azimuth and Range

3

Issues with ILS

Multi-Path Propogation
Interference - Radio (fm)
False Localiser/Glide Path
Only 40 channels
No special Procedures for slow/light AoC
Cannot be hilly - site specific
Long straight in final approach

4

MLS Advantages

200 channels
Not limited to straight in approaches
Correct back course
Operate in hilly/not prepared sites
No multipath interference
Built in DME
Compatible with ILS, Area Nav, Autopilot

5

Operation

MLS is Time Devision Multiplexing (TDM)

Information is time shared between angle and data functions and transmitter in combined packages

6

TRSB

Time referenced scanning beams - scans area of coverage right/left up/down

Hits AC, starts timer, Stops timer, when beam comes back

Determines azimuth + vertically

7

Coverage

40 degrees either side of extended CL

0.9 degrees low 20 degrees high out to 20nm

8

Range Info

Derived from precision DME (v.accurate) - 22nm from transponder

9

Frequency and Indentifying

S-Band: 5031-5091MHz at 300kHz spacing (4 letter morse code 6 times/sec)

Digital Frequency

Elevation signal Tx signal on same frequency TRSB

10

Accuracy

95% lat and vertically accuracy within 20nm - 60ft above MLS datum point

Cat III accuracy: 20 ft azimuth and 2 ft elevation

11

Display

Multi-Mode Receiver fitted (MMR)
DME/P Installed - curved approach possible
If not installed, ILS like approach