09 MLS

Question 1

MLS channels?

Answer 1

MLS uses 200 separate channels in SHF frequency band.
5031.0 – 5090.7 MHz

Question 2

MLS principle of operation?

Answer 2

MLS provides horizontal, vertical and distance guidance during the approach, and horizontal guidance during the missed approach.

To and from pulses from a sweeping beam allow the AC to understand were you are, uses time division multiplexing. ATC are able to upload a path via ACARS to inform the pilots what path to follow.

The information displayed onboard represents a 2D presentation of a 3D segmented approach.

Question 3

MLS Distance Infomation?

Answer 3

Distance information is provided by DME/P (Precision DME).

Question 4

MLS Aircraft equipment?

Answer 4

• Aircraft need to be fitted with a multi-mode receiver (MMR) to receive MLS signals. (Combines multiple systems, reduces crew training)
• MLS cockpit displays are similar to ILS.

Question 5

MLS without DME/P

Answer 5

MLS without DME/P allows a straight-in, ILS type approach only.

Question 6

MLS Coverage?

Answer 6

The area of MLS coverage is +/- 40° of nominal centreline out to 20 NM.

Question 7

How can reflections be reduced?

Answer 7

Signal can be started and stopped to avoid noise from stationary objects.