Circling
There are to types of circling.
1. Circling approach to Instrument RWY xx and
2. Circle to land (for other RWY).
what does it mean:
1. Some instrument procedures designed for certain RWY may be offset up to 30 degrees. If they are offset, instrument procedure may be called for example VOR/DME Circling RWY xx. Specification for offset is set by ICAO for cat a,b,c,d approach. In that case you land on that RWY for which Instrument approach is designed and,
2. Circle to land, means that you make instrument approch for RWY xx and due to mainly strong wind, aircraft on the instrument approach procedure, having RWY in sight, may ask for Circling for another RWY. Pilot is performing that manoeuver constantly having RWY in sight and of course it is done visually.
You may take a Jeppesen charts to see some procedures with both options where in case of circling to land there are different minima specified and displayed on the Instrument approch chart.
If I am wrong, please correct me.
BRGDS
ATCO2