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determine the distance between radar and reflected objects. Radar is very much

used in airplanes, spacecraft’s, land vehicles, ships, astronomical bodies and terrain.

Generally the electromagnetic wave travels in a straight line, but slightly varies due to

the weather and atmospheric conditions in the space. Special antennas are required to

receive the reflecting signal in a desired direction. Consequently the radar measures

the elevation and azimuth directions of reflected object. All these principles are

fundamentally incorporated into the radar system. This allows the estimation of the

direction, height, distance and the position from the reflecting objects. Radar operates

with microwave and ultra-high frequency signals.

The advantages of radar as compared to normal visual observations:

• Radar operates in all kinds of weather conditions

• It is capable to operate in any time with a long range

• Radar has wide-range of coverage with high frequency signals

• It is able to penetrate through walls and snow layers also

• Radar can detect moving objects with fairly good resolution and recognition

• Radar Entomology covers scientific study of insect navigation and insect flight

• Whole hemisphere can be observed by radar.

However, radar is used to find the position of other objects also. The main appli-

cation areas of radar for navigation is Military, Space, Air traffic control, Remote

sensing and Ground traffic control etc. However, nowadays radars are also used in

biomedical instruments and mining.

Radar Entomology has played a vital role in understanding insect flight and also

pest and migratory fliers, which attack agricultural fields and other trees in the forest.

Instrument Landing Systems (ILS) and Microwave Landing

System (MLS)

For flights, approach phase is more difficult, since some maneuvering is done before

final descent. The word approach is used to describe the phase of flight, which

immediately precedes the landing. Of course, the landing phase of flight requires

highest navigational accuracy, particularly in the vertical direction.

Landing is very critical for flights. Landing is usually designed to be at a 3°

descent angle and on a track aligned with the central line of runway. Generally the

final descent path starts at 4 NM from threshold and intersects or touches the runway

at a point 1000 ft/300 m past the threshold. The pilot will stabilize the aircraft within

the straight section of the approach of 4 NM (i.e. almost within 2-min), such that

the aircraft will touch the runway with desired 3° decent, airspeed and ground track.

The ultimate objective of landing is to land the aircraft safely.