Circling Approach: A circling Approach is a maneuver that an Aircraft has to perform while on Approach to land on the Runway.
This maneuver is required to be carried out anytime the Final Approach Course is not aligned with in 30° of the Runway Direction.
The Aircraft is required to carry out a turn to land after having the Runway in sight.
Simultaneous ILS Approaches: For carrying out simultaneous ILS approaches the distance between the parallel Runway centerlines should be more than 4300 feet.