Navigation & Control Guidance

Navigation & Control Guidance 

What a Navigation

n The Traffic Alert and Collision Avoidance System (TCAS) has had 

extraordinary success in reducing the risk of mid-air collisions. Now mandated on 

all large transport aircraft, TCAS has been in operation for more than a decade 

and has prevented several catastrophic accidents. TCAS is a unique decision 

support system in the sense that it has been widely deployed (on more than 

25,000 aircraft worldwide) and is continuously exposed to a high-tempo, complex 

air traffic system. TCAS is the product of carefully balancing and integrating 

sensor characteristics, tracker and aircraft dynamics, maneuver coordination, 

operational constraints, and human factors in time-critical situations. Missed 

or late threat detections can lead to collisions, and false alarms may cause pilots 

to lose trust in the system and ignore alerts, underscoring the need for a robust 

system design. Building on prior experience, Lincoln Laboratory recently 

examined potential improvements to the TCAS algorithms and monitored 

TCAS activity in the Boston area. Now the Laboratory is pursuing new collision 

avoidance technologies for unmanned aircraft.

Instrument Landing System ( ILS)

1. ILS is the only Navigational Aid for Landing and final Approach having two transmitters installed at far end of the Runway.This is system that uses VHF & UHF radio waves. ILS has been in usage since 1946.This is only because of ILS system that today the AFCS has been very efficient even during automatic landing.
2. Unlike ILS the VOR,ADF and DME are the navigational aid for airway or air route.
3. The two subsystems of ILS systems are (1) Localizer (LOC) (2) Glide Slope (GS)

Localiser

The horizontal navigational aid for landing of and air craft is called localiser that sets the plane aligned with the center line of the runway.

The localizer transmits VHF with frequency range of 108-112 MHz with increment of 0.5 MHz.

The Localiser transmits two lobs let & right with 90 Hz & 150 Hz.The lobs cut each other or extended center line of the runway.the localiser have also there morse code.the lobs as shown as under:

Glide Slope

The vertical navigational aid for landing is called glide slope(GS).Glide Slope transmit UHF of 328.6 - 335 Mhz.The glide slope frequency is automatically set when the crew tune the frequency of localier.

Marker Beacons

In Instruments landing system the visual and audible cues to the crew are provided by an other very important navigational aid that is called "MARKER BEACONS".The marker beacons are sites at two or three distances on the extended center lines of the runway and provides the NavAid to confirm the crew of progress.They transmit 75 Mhz with there unique morse code with 3-4 W of power. The marker beacons are divided in to three categories such as (1) Outer Marker (2) Middle Marker  (3) Inner Marker

(1) Outer Marker (OM): the outer marker is sited at 4 - 7 miles from runway thresholds.It Transmit dash dash(- -) morse code by operating at frequency of 400 Hz.When the aircraft approaches at Outer marker the Cyan light in on on ILS instrument and the OM icons gets high on the display.

(2) Middle Marker (MM): the milddle marker is sited at 3500 ft from runway thresholds.It Transmit alternating dash dot(- .) morse code by operating at frequency of 1300 Hz.When the aircraft approaches at Outer marker the Yellow light in on on ILS instrument and the MM icons gets high on the display.

 (3) Inner Marker (MM): the inner marker is sited at 2000 ft from runway thresholds.It Transmit dot dot(..) morse code by operating at frequency of 3000 Hz.When the aircraft approaches at Outer marker the White light in on on ILS instrument and the IM icons gets high on the display.