What is a circling approach and why is it necessary? I know that if a runway is not suitable for an instrument approach, the pilots should execute landing on a runway which has an instrument approach available.
A circling approach is executed on an instrument approach procedure which or where the final approach segment is not aligned directly with the runway of intended landing. Circling approaches can also be flown on instrument approaches where the pilot opts to land on another runway not aligned with the final approach segment, but which has more favorable wind conditions, obstacle clearance, greater landing distance available, or some other characteristic which makes it more desirable to land on.
To add to the above points...
Circling Approaches are used when the Approach you want to use and the runway you want to use are not aligned with each other. Say for instance, you are arriving to the terminal area from the North. The runway you want to use is from the South (probably due to wind). You want to get down to the ground ASAP. You can get cleared to approach the airport using an IAP with a Southbound Final Approach Course. They will also clear you to circle the field in a certain direction. We will use East in this example. You will then get clearance to land on the Northbound (from the south) runway. A play by play would be to:
- Follow the full procedure for the IAP with the 180° Final Approach Course.
- Once you reach your Circling Minimums, maintain you’re altitude, and turn 30° to 60° to your left.
- Turn back to your 180° heading in time to stay no more than 1.3 miles away from the runway surface for Category A aircraft (unless the airport has published alternate circling distances). It would be similar to a (right in this case) downwind leg
- Parallel the runway to a point where you can make a normal downwind to base turn.
- Start your descent to landing
- Land on runway 36
If you never get the runway environment in sight, go missed at the original MAP.
If you lose sight of the runway environment at any time during your circling maneuver, immediately circle back over the runway to fly above it on your missed approach course. And go missed. Remember, the safest place in the airport environment is directly above the center of the runway.
One thing to be aware of on Circling Approaches is that the Circling Minimums are typically below Traffic Pattern Altitude. You will be flying slower and closer to the ground in the airport environment than you are used to. Caution must be exercised.
Also, the Circling Approach does not have to be a complete 180° turn around to land. It could be in any direction.
Finally, some approaches only have Circling as an option. This is due to the approach itself not being aligned with the runway. In the example below, the runway is aligned 179° and 359° magnetic.
Even with Sean's edits that last sentence is confusing. Of course it is ideal to land on a runway with an instrument approach, but when the preferred landing runway is NOT served by an instrument approach, the pilot must follow a procedure to get below the clouds and be able to see to land.
This can be accomplished by radar vectors to a visual approach, but depending on the ceiling, minumum vectoring altitude, and the published approach minimums it may be advantageous to shoot an approach to a runway not in use, and once the runway is in sight, circle to land by maneuvering to join the final portion of the VFR landing pattern.