FAA 7460-1 › Michigan ›
Building or using a crane near Grindstone Air Harbor (29C)?
Grindstone Air Harbor in Port Austin, Michigan 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 29C 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, 611 ft above sea level:
| Distance from nearest runway | Notice required above (height over 611 ft) | …which is this elevation (AMSL) |
|---|---|---|
| 250 ft | 5 ft | 616 ft |
| 500 ft | 10 ft | 621 ft |
| 1,000 ft | 20 ft | 631 ft |
| 2,000 ft | 40 ft | 651 ft |
| 3,000 ft | 60 ft | 671 ft |
| 5,000 ft | 100 ft | 711 ft |
| 7,500 ft | 150 ft | 761 ft |
| 10,000 ft | 200 ft | 811 ft |
| Beyond 10,000 ft | Only the 200-ft-above-ground rule applies (77.9(a)) | |
If your ground is lower than 611 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) |
|---|---|---|
| 18/36 | 1,800 ft | 611 / 626 |
Filing Form 7460-1 near 29C
- 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
- E53 — Engler Fld (13 nm)
- BAX — Huron County Meml (16 nm)
- 6D9 — Iosco County (27 nm)
- 98G — Sebewaing Township (30 nm)
- OSC — Oscoda/wurtsmith (32 nm)
- Y83 — Sandusky City (36 nm)
Source: FAA airport, runway and runway-end data (NASR cycle effective 2026/10/01). Screening only — the FAA issues determinations.