Ace the ASE Approach: Circle-to-Land

Sometimes it is what you don't see on an instrument approach chart that tells a story. In previous articles, we have brought up that the absence of the text "Grooved" by a runway description is the indication the runway will be slippery when wet. If rain is in the forecast, look for that missing text to include in your preflight planning and briefings.

If you plan to circle from an instrument approach, another item to be on the lookout for is the inverse C in the minima section. In 2013, the FAA modified the criteria for circling approach areas via TERPS 8260.3B Change 21. This expanded the circling approach area to provide improved obstacle protection. As a result, circling minima at certain airports increased significantly. Charts where these criteria have been applied can be identified by the symbol in the CIRCLE-TO-LAND minima box.

When the change occurred in 2013, who would have thought that 8 years later it would not have been fully implemented? The FAA said the change would occur "on an as-revised basis as the new criteria are applied by the FAA and issued via their source documents."

As the crow files (or airplane not getting vectored for an approach), my cabin sits 34 NM from the Aspen airport and 3122 feet above field elevation. Since the first measurable snowfall of the season fell last week and ski season is just around the corner, let's consider the impact of the lack of an inverse C on a trip to Aspen, CO (KASE).

If we look at the LOC DME-E minimums, there is no inverse C indicating the approach still uses the standard circling approach minimum radius. For a Category C aircraft flying 140 knots or less on the circle, obstacle protection was accounted for within 1.7 NM circling radius.

When the approach migrates to the expanded circling maneuvering airspace radius, that obstacle protection nearly doubles from 1.7 NM to 3.3 NM. These distances, dependent on aircraft category, are also based on the circling altitude which accounts for the true airspeed increase with altitude.

When can we expect KASE to start using the expanded circling area? The other thing we always need to remember to look at in your preflight planning and briefings is NOTAMS.

In August 2021, a NOTAM was published for the LOC DME-E for KASE amending the circling minimums for the approach. Why were the circling minimums increased? They were increased for the expanded circling maneuvering airspace radius change.

For a Category C aircraft flying 140 knots, your minimums increase from 10220' (2383' HAA) to 10960' (3122' HAA). They also added the note "Circling NA for CAT C southwest of RWY 15-33." In other words, the terrain southwest of RWY 15-33 beyond the old standard of 1.7 NM would have significantly increased the minimums, so by limiting circling to the northeast of the runway, the minimums were only increased by 740'. In addition to dusting off your winter operations skills, remember to check NOTAMS and look for that inverse C.