What are the functions of the glide slope and localizer?

Glide slope:The glide slope (or glide path) is an imaginary line that travels from the approach end of the runway upwards to the aircraft that is about to land. For better airports, there is usually a visual approach glide slope indicator.

When an aircraft is above the glide slope, the touchdown speed will be higher and there is a chance that it may land too far down the runway, forcing a go-around. This is because a higher altitude is exchanged for more speed as the aircraft descends at a higher rate of descent.

When an aircraft is below the glide slope, there is a chance that he may land short of the runway and is more prone to stalls. This is because the rate of descent has to be reduce and an inexperienced pilot may instinctively pull up, causing a loss of speed.

When an aircraft is on the glide slope, the aircraft will land at the correct touchdown point and at the best speed. This is because altitude is reduced at an optimum rate such that speed is neither increased nor decreased.

Localiser:The localiser is the lateral component of the instrument landing system (ILS) that aligns the aircraft with the runway.

It is kinda like a handrail that ensures that the aircraft is able to arrive at the runway centre.

The localiser and radio glide slope indicator combined into the ILS ensures that the aircraft follows a line right to the touchdown point.