VOR A approach question

A pilot's question about the VOR-A approach into Willow Run Airport (KYIP) highlights a subtle but operationally significant gap in how 14 CFR 91.175 applies to circling-only procedures. The VOR-A designation itself signals that the approach is not aligned closely enough with any single runway to qualify for straight-in minimums, so the chart publishes only a circling MDA referenced to airport elevation rather than a runway-specific touchdown zone elevation (TDZE). This creates the exact ambiguity the original poster raises: 91.175(c)(3)(i) permits descent to 100 feet above TDZE using only the approach lights as a visual reference (absent red terminating or side-row bars), but that regulatory language presumes a runway and a published TDZE exist. On a circling approach with no assigned runway, there is technically nothing to measure "100 above TDZE" against until the pilot commits to a specific runway for the circle-to-land maneuver.

The practical workaround the poster proposes—cross-referencing another instrument approach plate to the runway they intend to circle to in order to extract that runway's TDZE—is a reasonable and commonly taught technique among CFIIs and check airmen, though it is not explicitly codified in the regs or AIM. An alternative, and arguably more defensible, interpretation is that when no TDZE is published for the approach in use, airport elevation serves as the reference point, consistent with how TERPS and AIM guidance treat MDA construction for circling procedures generally. Either approach requires the pilot to have already identified which runway they plan to circle to well before reaching minimums, reinforcing that circling approaches demand more pre-planning and situational awareness than straight-in RNAV or ILS procedures where TDZE is explicitly charted and the runway environment is unambiguous from the start.

This matters to working pilots because circling approaches remain disproportionately represented in CFIT and loss-of-control accident data, precisely because of the added cognitive load of maneuvering visually at low altitude while simultaneously managing regulatory minima that are less precisely defined than on straight-in approaches. Many Part 135 and Part 121 operators restrict or outright prohibit circling approaches below certain visibility or ceiling minimums, or require additional training and checkride emphasis on the maneuver specifically because of this kind of ambiguity. For corporate and charter crews flying into airports like Willow Run that still rely on legacy VOR-only circling procedures for certain runways, understanding exactly how the 100-foot approach-light credit applies—or doesn't—before ever briefing the approach is essential, since working it out at minimums in actual IMC is the wrong time to resolve a regulatory interpretation question.

More broadly, this scenario reflects why the FAA and industry have spent the past two decades pushing to replace VOR and circling-only procedures with RNAV (GPS) approaches offering LPV or LNAV/VNAV vertical guidance and, where possible, straight-in minimums to more runways. The FAA's VOR MON (Minimum Operational Network) initiative has steadily decommissioned VORs and their associated approaches nationwide, and many airports have gained RNAV overlays specifically to eliminate the kind of circling-only, non-precision procedures that generate exactly this type of interpretive gray area. Until Willow Run or similar fields gain more direct RNAV coverage to every runway, however, pilots will continue encountering VOR-A style approaches, and crews should brief the runway they intend to circle to, its TDZE, and their planned visual maneuvering path well before the FAF—treating the regulatory ambiguity as a trigger for more conservative personal minimums rather than a loophole to press lower.