FAA 7460-1 › Montana ›
Building or using a crane near Tillitt Fld (1S3)?
Tillitt Fld in Forsyth, Montana is a public-use airport. Under 14 CFR 77.9, anything within 20,000 feet of its runways that rises above a 100:1 slope needs FAA Form 7460-1 at least 45 days before construction. Check your exact site free.
No address handy? Try 16700 Saticoy St, Van Nuys, CA 91406
How tall can you build near 1S3 without filing?
The notice surface rises 1 foot for every 100 feet of horizontal distance from the nearest point of the nearest runway, starting at the runway's elevation. Using the lowest runway-end elevation, 2,728 ft above sea level:
| Distance from nearest runway | Notice required above (height over 2,728 ft) | …which is this elevation (AMSL) |
|---|---|---|
| 250 ft | 2 ft | 2,730 ft |
| 500 ft | 5 ft | 2,733 ft |
| 1,000 ft | 10 ft | 2,738 ft |
| 2,000 ft | 20 ft | 2,748 ft |
| 3,000 ft | 30 ft | 2,758 ft |
| 5,000 ft | 50 ft | 2,778 ft |
| 7,500 ft | 75 ft | 2,803 ft |
| 10,000 ft | 100 ft | 2,828 ft |
| 15,000 ft | 150 ft | 2,878 ft |
| 20,000 ft | 200 ft | 2,928 ft |
| Beyond 20,000 ft | Only the 200-ft-above-ground rule applies (77.9(a)) | |
If your ground is lower than 2,728 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 20,000-ft area where the 100:1 notice slope applies; inner line: 5,000 ft.
| Runway | Length | End elevations (ft AMSL) |
|---|---|---|
| 09/27 | 4,799 ft | 2729.3 / 2727.7 |
Filing Form 7460-1 near 1S3
- 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
- 6U7 — Hysham (24 nm)
- M46 — Colstrip (25 nm)
- MLS — Frank Wiley Fld (32 nm)
- 3U4 — St Labre Mission (42 nm)
- 00U — Big Horn County (53 nm)
- 8U1 — Sand Springs Strip (62 nm)
Source: FAA airport, runway and runway-end data (NASR cycle effective 2026/10/01). Screening only — the FAA issues determinations.