Are Circling Approaches Still Useful

Martin:

“Back in the days before GPS, circling minimums were often the only way to land on a favorable runway after an instrument approach. That’s because creating a straight-in instrument approach required expensive navigation ground equipment, so the FAA had to choose carefully which runway ends to provide with an approach.

These days, GPS and WAAS make it so much easier and more affordable to create instrument approaches. For the most part, today the only reason why a straight-in instrument approach procedure is sometimes not offered is when terrain or obstacles get in the way.

So do circling approaches still make sense these days? Yes, they do – though not to land on a runway you could not otherwise land on, but to get there more efficiently. Think of a typical airport with an east-west runway, offering RNAV approaches with LPV minimums to both runway 9 and runway 27. You are flying to this airport from the west, on an afternoon with strong westerly winds. After enjoying a nice tailwind enroute, you need an instrument approach to get below the 1,000-foot overcast, under which the latest weather report promises good visibility. The RNAV runway 27 approach does that just fine, but it does require that you fly several miles past the airport on the east side before joining the approach and landing into the wind.

This is where a circling approach can help. Remember that the purpose of an approach is not just to laterally align you with a runway – in fact, pure circling approaches like the a VOR-A don’t even provide that alignment – but also to allow a safe and legal descent from the minimum enroute or vectoring altitude, hopefully low enough to see the airport and land. So, if in our example we fly the RNAV runway 9 approach, we can pick up an Initial Approach Fix or vectors to final pretty much on our direct path to the airport, descend through the cloud layer, and then – once we see the runway – fly a pattern visually under the overcast and with decent visibility to runway 27. And voilà – we have just used a circling approach to safely land into the wind while avoiding the extra five to ten minutes of flight time it would have taken to fly the straight-in approach to Runway 27.

I should add that this is only a good idea if the ceiling is reasonably high and the visibility under the clouds is reasonably good. If the visibility is poor, or if it’s dark, or if the actual ceiling is only a hair above circling minimums for the approach, I’ll gladly fly the extra miles for the full straight-in approach and do it more safely with less stress. But under the right conditions, a circling approach can be a safe efficiency tool.”