Building or using a crane near Isabel Muni (3Y7)?
Isabel Muni in Isabel, South Dakota is a public-use airport. Under 14 CFR 77.9, anything within 10,000 feet of its runways that rises above a 50:1 slope needs FAA Form 7460-1 at least 45 days before construction. Check your exact site free.
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How tall can you build near 3Y7 without filing?
The notice surface rises 1 foot for every 50 feet of horizontal distance from the nearest point of the nearest runway, starting at the runway's elevation. Using the lowest runway-end elevation, 2,383 ft above sea level:
| Distance from nearest runway | Notice required above (height over 2,383 ft) | …which is this elevation (AMSL) |
|---|---|---|
| 250 ft | 5 ft | 2,388 ft |
| 500 ft | 10 ft | 2,393 ft |
| 1,000 ft | 20 ft | 2,403 ft |
| 2,000 ft | 40 ft | 2,423 ft |
| 3,000 ft | 60 ft | 2,443 ft |
| 5,000 ft | 100 ft | 2,483 ft |
| 7,500 ft | 150 ft | 2,533 ft |
| 10,000 ft | 200 ft | 2,583 ft |
| Beyond 10,000 ft | Only the 200-ft-above-ground rule applies (77.9(a)) | |
If your ground is lower than 2,383 ft you can build taller by the difference; if it's higher, less. Cranes count at their maximum height. The free check above uses USGS ground elevation for your exact spot.
Runways and notice boundary
Dashed line: the 10,000-ft area where the 50:1 notice slope applies; inner line: 5,000 ft.
| Runway | Length | End elevations (ft AMSL) |
|---|---|---|
| 13/31 | 3,009 ft | 2386 / 2383 |
Filing Form 7460-1 near 3Y7
- File online through the FAA's OE/AAA system at least 45 days before construction or before applying for a building permit, whichever is first. Filing is free.
- You need NAD 83 coordinates, site ground elevation, structure height above ground and above sea level.
- Construction on airport property always needs notice, whatever the height.
More: Do I need to file Form 7460-1? · Cranes and Form 7460-1
Other public-use airports nearby
- D58 — Timber Lake Muni (15 nm)
- 84D — Cheyenne Eagle Butte (26 nm)
- D07 — Faith Muni (32 nm)
- 5P2 — Mc Laughlin Muni (37 nm)
- LEM — Lemmon Muni (42 nm)
- 6V5 — Bison Muni (44 nm)
Source: FAA airport, runway and runway-end data (NASR cycle effective 2026/10/01). Screening only — the FAA issues determinations.