What is Circling Approach?

[Mohsin87]

I've some idea about it basically but not thoroughly clear tbh.

[172_driver]

A straight-in precision approach (i.e. ILS, PAR) or non-precision approach (i.e. VOR, NDB, GPS, SRA) brings you into a slot, or box, from which you can land straight-in. That means, the runway is more or less dead ahead. The runway can actually be up to 30 deg offset, or 15 deg for larger aircraft, and still be called a straight-in approach.

The alternative to having a straight in approach is a a circling approach. Due to terrain around the airport, or other reasons, it may not be possible to design a straight-in approach. It could be a hill a few miles from the runway that the aircraft would hit (or be too close for comfort to) if it was attempting a normal descent to the runway in its axis. In this case you'll design a circling approach. The navigation aid, such as a VOR, NDB or Localizer, will bring you to a point above the airport from which you circle down under visual conditions to the landing runway. A bit like a visual traffic pattern if you are flying VFR. If there are multiple runways you can circle to the most appropriate one considering length, wind etc. It's a visual maneuver.

Another reason to do a circling approach could be if the airport you are going to has a straight-in approach in only one direction, but because of the wind landing straight-in is not possible (too much tailwind). At one point, some 1-2 miles before the runway, you break off the approach by a 45 deg turn, join a left or right downwind to land in the opposite direction. Again, like a visual traffic pattern.