FAA airspace screening · Part 77 + tower line-of-sight
Screen Part 77 & line-of-sightbefore you file a 7460.
LOS Analyzer tells developers and consultants — in minutes — whether a proposed structure penetrates FAA Part 77 surfaces or breaks a control tower's sightline to the runway. Terrain-aware, curvature-corrected, and ready to generate your Form 7460-1 draft. Your first screening is free; every one after that is $99.
Watch the 3-minute demo on YouTube (opens in a new tab)
- Standard
- 14 CFR Part 77 surfaces & ATCT line-of-sight
- Terrain + curvature + refraction
- Public validation scoreboard
The stakes
A hazard determination can kill a project.
If a structure penetrates a Part 77 surface and the FAA issues a Determination of Hazard, the project can lose financing, get redesigned, or be scrapped outright — sometimes after months of work. Yet the only way most teams find out is to file a 7460-1 and wait, or to commission a full airspace study that costs $5,000–$15,000 and takes weeks.
The FAA's free Notice Criteria Tool tells you whether you must file. It doesn't show which Part 77 imaginary surface controls your site or by how many feet you clear it, and it says nothing about whether the control tower can still see the runway. So the highest-stakes question — "how big a problem is this, and why?" — is the one that's hardest and slowest to answer.
Full airspace study
$5k–$15k
- 2–6 week turnaround
- Pay before you know feasibility
- Slow to iterate on massing
- Overkill for a go / no-go check
LOS Analyzer screen
$99 · minutes
- ✓ Answer before you file
- ✓ Part 77 + tower line-of-sight
- ✓ Terrain & curvature modeled
- ✓ 7460-1 draft generated
What you get
One screening. Three deliverables you can put in front of a client.
Every $99 run gives you the live 3D analysis in the app, a consultant-style PDF report, and a pre-filled Form 7460-1 aid — all from the same inputs.
Terrain-aware 3D line-of-sight, live on the map.
Search any US public-use airport, place the control tower cab, drop in the building corners (or upload a site plan and we read the coordinates), and set a height. Sightlines are generated automatically from the tower eye to every FAA runway, threshold to threshold — no segment drawing required.
- ✓ Ray tracing over real terrain with earth curvature and refraction
- ✓ Part 77 surfaces built from the FAA NASR runway record, classification auto-detected per runway end
- ✓ Instant verdict banner, blocked / clear rays on the satellite view, click any ray for the numbers
- ✓ 3D terrain profile showing exactly where the sightline is cut and by how many feet
Pages 7–8 of a 16-page screening report: the obscured-zone overview and the first per-vantage plan + profile. Click to enlarge.
A consultant-grade PDF, not a screenshot.
The report reads like the line-of-sight study an airspace consultant would hand you: a sightline is drawn from the controller's eye through the building centre and every corner, grazing the roof and continuing until it meets the ground again. The ground in between is the obscured zone — the surface the tower can no longer see — mapped in red and tabulated by bearing, distance, roof elevation, and length.
- ✓Cover page and screening disclaimer
- ✓Executive summary with the go / no-go verdict
- ✓Annotated satellite map snapshot
- ✓3D terrain profiles for every tower-to-runway ray
- ✓Vantage points & obscured zone — map + table
- ✓Plan + profile page for the building centre and each corner
- ✓Part 77 surface penetration by runway end
- ✓Methodology and full inputs appendix
Every page is footered "preliminary screening only" — it is built to support a PE's review and a 7460-1 filing, not to replace them.
Form 7460-1, pre-filled from the same inputs.
If the screening says you need to file, you don't start from a blank form. LOS Analyzer generates a pre-fill aid for FAA Form 7460-1 (Notice of Proposed Construction or Alteration) with the geometry already worked out:
- ✓ Structure latitude / longitude in decimal and DMS, with the WGS84 → NAD83 caveat spelled out
- ✓ Site elevation, height AGL, and total height AMSL
- ✓ Nearest public-use airport with distance in nautical miles and true bearing from the structure
- ✓ Notice type and structure type pre-selected — proponent, schedule, and contact fields left for you
Clearly stamped as a pre-fill aid. The official notice is still filed by you, through the FAA OE/AAA portal.
Why it works
Three reasons consultants and developers screen here first.
Instant, terrain-aware Part 77 + LOS
Drop in an airport and a proposed structure and get an immediate read on whether it penetrates the Part 77 primary, horizontal, conical, approach, or transitional surfaces — and whether it breaks the control tower's line of sight to the runway. Modeled with real terrain, earth curvature, and atmospheric refraction, not a flat 2D guess.
An engine you can audit
Most tools ask you to trust a black box. LOS Analyzer shows its test scoreboard — named cases whose expected outcomes are verifiable by construction from the documented geodesy. The math is on the table. Checking it against real FAA determinations is still to come, and the scoreboard below says exactly what is proven.
Generates your Form 7460-1 draft
When the screening points to a filing, you don't start from a blank page. LOS Analyzer produces a multi-page PDF report and a pre-filled FAA Form 7460-1 (Notice of Proposed Construction or Alteration) draft from the same inputs — ready for your engineer to review and submit.
No black box
A validation scoreboard you can audit.
High-stakes regulatory calls deserve a tool that shows its work. Every release runs a suite of named test cases whose expected outcomes are verifiable by construction from the documented geodesy — curvature drop, chord interpolation, and Part 77 surface elevations — so you can check the math without running the code.
Honest scope: the current scoreboard proves the engine is internally self-consistent with its own formulas. Validation against published real-world FAA determinations is being added in the open — we'd rather tell you exactly what's proven than imply more.
Read the full methodology| ID | Case | Result |
|---|---|---|
| A1 | Structure above midpoint LOS — BLOCKED | ✓ PASS |
| A5 | Runway beyond radio horizon — BLOCKED | ✓ PASS |
| A7 | Part 77 approach penetration detected | ✓ PASS |
| A9 | Part 77 horizontal penetration detected | ✓ PASS |
| A10 | Compliant structure below horizontal surface | ✓ PASS |
| B2 | High-terrain field (DEN-class) blockage | ✓ PASS |
Excerpt — full scoreboard and intake form for real FAA cases live in the repository's validation suite.
Where it fits
A pre-screen, in its proper place.
LOS Analyzer sits at the front of the obstruction process — informing whether (and how) to file, never replacing the FAA's determination or your professional engineer.
- 01
Site concept
Developer / designer
- 02
LOS Analyzer screen
← you are here
- 03
Form 7460-1
Notice of construction
- 04
OE/AAA study
FAA aeronautical review
- 05
Determination
Hazard / no hazard
Clear result → support a simpler 7460-1. · Penetration detected → refine the design before you file.
What we track
Built on the FAA's public obstruction archive.
The case lookup, The Docket and the data report are free to read. They come from the FAA's own OE/AAA records, and every number below is read from the same data files those pages are built from.
- 73,508FAA obstruction cases from 2026, one page eachLook any case up by its number. Data as of Sep 12, 2026.
- 993airports with a page of the filings near themPlus 1,294 organisations with a page of their 2026 filings.
- 9,426new filings in the latest Docket editionWeek 37, 2026 · Aug 22 – Sep 12, 2026.
- 1,815,083Part 77 filings analysed in our data reportFAA review times, outcomes and expiring determinations. Data as of Sep 12, 2026.
FAQ
The questions filers actually ask.
Do I need to file an FAA Form 7460-1?
Generally, yes if your construction or alteration is more than 200 ft above ground level, is on an airport, or sits within the FAA's notice radius and penetrates a sloped notice surface — 100:1 within 20,000 ft of a runway longer than 3,200 ft, 50:1 within 10,000 ft of a shorter runway, or 25:1 within 5,000 ft of a heliport (14 CFR Part 77, Subpart B, §77.9). LOS Analyzer screens these criteria for your specific site so you know before you commit to a design.
What is Part 77?
14 CFR Part 77 defines a set of imaginary surfaces — primary, horizontal, conical, approach, and transitional — projected around every public-use airport. An object that penetrates one of these surfaces may be an obstruction to air navigation and triggers an FAA aeronautical study. The surfaces' shape and elevation depend on each runway's approach classification, which is exactly what the screening computes.
Is this a substitute for an FAA determination?
No. LOS Analyzer is a preliminary screening that tells you whether — and how — to file. Only the FAA issues an official Determination of No Hazard or Hazard through the OE/AAA process, and a licensed professional engineer should review the structural specifics before anything is submitted. We are deliberate about where the tool stops and a PE begins.
How accurate is the analysis?
The engine is terrain-aware (elevation from OpenTopoData) and corrects for earth curvature and atmospheric refraction (k = 7/6, ITU-R P.834). Every assumption and limit is published in the methodology, and a validation scoreboard documents named test cases with outcomes verifiable from the formulas. It is a screening model: real determinations also depend on runway visual-range requirements, exact tower-cab geometry, and FAA specialist judgment that no automated tool reproduces.
How much does it cost?
Your first screening report is free. After that, a single screening report is $99 — a fraction of the $5,000–$15,000 and multi-week turnaround of a full airspace study. Firms that file often can buy a 5-pack at $80 per report or an annual seat for unlimited screening. No subscription required to run your first one.
Not sure if your site needs a filing?Read the 7460 guide →
Know before you file. Run a screening in minutes.
Place the airport, drop in your structure, and get a Part 77 + line-of-sight screening with a 7460-1 draft — for $99, not five figures.