Site Elevation Survey for Airport NOC — WGS-84 & AMSL Certification
Every AAI NOC application — whether for a building, tower, solar plant, or wind turbine — starts with one non-negotiable input: a site elevation survey for airport NOC that gives AAI your exact ground elevation and coordinates. Skip this step, get it wrong, or submit it in the wrong format, and your NOCAS application will sit in remarks while the rest of your project waits. This page explains what a site elevation survey actually involves, the accuracy AAI expects, and how the certificate needs to be prepared before you file.
What Is a Site Elevation Survey for Airport NOC?
A site elevation survey for Airport NOC is the field survey that establishes two things AAI needs before it will process any height clearance application: the site coordinates in WGS-84 datum and the ground elevation in Above Mean Sea Level (AMSL), also referred to as the Reduced Level (RL) of the site. Together, these values are what NOCAS uses to calculate the maximum permissible top elevation for your plot.
This isn’t a generic land survey. AAI’s system checks your surveyed coordinates against the Colour Coded Zone Map or the airport’s obstacle limitation surface for that exact location, so the accuracy and format of the data determines whether your application gets accepted on the first pass or bounced back with remarks.
AAI’s Accuracy Requirements for Site Elevation & Coordinates
AAI’s guidelines specify exact tolerances for this survey, and applications that don’t meet them are routinely rejected or sent back for resurvey:
- Site elevation (AMSL): accuracy within 0.5 metres
- WGS-84 coordinates: accuracy to 1/10th of a second, expressed in the format DD°MM’SS.s”
- Position accuracy: within 3 metres
- Corner points: a minimum of four coordinates covering all corners of the plot, including the point nearest to the airport — even for a triangular plot, a fourth coordinate is required on the side facing the airport
- Vertical datum: clearly stated (MSL/Indian Datum), with transformation parameters where applicable, and referenced to a recognised permanent benchmark or GNSS control point
These aren’t suggestions — NOCAS will not accept an application where the submitted data falls outside these tolerances, which is why the survey has to be done with DGPS or Total Station instruments capable of meeting them, not a handheld GPS reading.
How the Site Elevation Survey Is Carried Out
- Benchmark identification — The survey starts from a recognised permanent benchmark or GNSS control point, so the elevation data can be traced back to a verifiable reference.
- Coordinate capture (WGS-84) — DGPS or Total Station instruments record latitude and longitude at all corner points of the plot, plus the point closest to the airport reference point.
- Elevation capture (AMSL / RL) — Ground elevation is recorded at the same points, referenced to Mean Sea Level, meeting AAI’s 0.5 m accuracy requirement.
- Structure height points — For buildings, this includes the highest point of the proposed structure and any rooftop installations — water tanks, lift motor rooms, telecom masts, lightning arresters — since AAI requires these included in the height declared.
- Certificate preparation — Data is compiled into AAI’s prescribed Site Elevation and Site Coordinates Certificate format, signed and stamped by a licensed or AAI-empanelled surveyor.
- Cross-check against CCZM — Before filing, the coordinates are checked against the published Colour Coded Zone Map for that airport to confirm the likely permissible height, so there are no surprises after submission.
Who Can Issue a Site Elevation Certificate for AAI NOC
AAI does not accept elevation and coordinate certificates from just any survey provider. Per AAI’s Air Traffic Management Circular (ATMC No. 06 of 2017), the certificate must be issued by a licensed surveyor, architect, or engineer — or a surveyor formally empanelled by AAI for this purpose. It’s worth noting specifically that certificates issued by the Survey of India are not accepted by AAI for this purpose, a detail that catches out applicants who assume a government survey agency’s data will automatically qualify.
Format of the Site Elevation and Coordinates Certificate
AAI publishes a prescribed format for this certificate, and NOCAS applications are checked against it. At minimum, the certificate needs to state:
| Field | Requirement |
|---|---|
| Site coordinates | WGS-84, DD°MM’SS.s” format, all corner points |
| Site elevation | Metres AMSL, 0.5 m accuracy |
| Benchmark reference | Description and elevation of the control point used |
| Survey method | Instrument used (DGPS / Total Station), date of survey |
| Surveyor details | Name, licence/empanelment number, signature and stamp |
| Applicant and site details | Plot/CTS/survey number, applicant name matching ownership documents |
Why This Survey Matters More Than It Looks
A large share of NOCAS applications don’t get rejected on height grounds — they get stuck in remarks because the submitted coordinates and elevation don’t match AAI’s format or accuracy requirements, or because the certificate wasn’t issued by a recognised surveyor. Since the applicant cannot alter data once a NOCAS application is submitted, an error caught after filing means starting over, not correcting in place. Getting the site elevation survey right the first time is what keeps the rest of the NOC timeline — and your construction or commissioning schedule — on track.
Where This Survey Applies
A certified site elevation survey is the starting point for every category of AAI NOC application — the underlying requirement doesn’t change, only the structure being assessed does. If you’re applying for building height clearance on a residential or commercial project, this survey establishes the plot’s boundary coordinates and elevation before your building’s proposed height is even considered. For a solar power project, the same survey is carried out across the full plant footprint, since a solar site’s boundary usually spans several acres rather than a single plot. For wind turbines and windmills, it’s done per turbine location, because each tower’s coordinates feed into its own total tip height calculation and can produce a different permissible height even within the same wind farm. It applies just as directly to telecom masts, transmission lines, and chimneys.
The requirement also doesn’t change by city — whether your site sits near Jaipur, Ahmedabad, Lucknow, Chandigarh, Kota, or Bhopal, AAI checks the same surveyed coordinates against that airport’s own Colour Coded Zone Map, so getting this survey right locally is what our city-specific Airport NOC survey teams handle as the first step on every project.
Why Get Your Site Elevation Survey Done by Surveying India
- In-house DGPS and Total Station survey teams, delivering coordinate and elevation data within AAI’s 0.5 m AMSL and 3 m positional accuracy requirements
- Certificates prepared in AAI’s prescribed Site Elevation and Coordinates Certificate format, so applications go in clean the first time
- DGCA-recognised drone survey capability for large or multi-structure sites — solar plants, wind farms, and industrial plots
- Direct, hands-on NOCAS filing experience, including how to respond to remarks around coordinate or elevation discrepancies without losing weeks on resubmission
- Over a decade of survey delivery for government bodies, PSUs, and private developers across airport-regulated zones in India
Need a certified site elevation survey for your AAI NOC application? Share your plot coordinates or address and we’ll confirm what data is needed, how long the survey will take, and what your likely permissible height looks like before you file.
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Frequently Asked Questions
What is a site elevation survey for Airport NOC? It’s the field survey that establishes your plot’s exact WGS-84 coordinates and AMSL ground elevation, which AAI uses through NOCAS to calculate the maximum height permissible at your site.
What accuracy does AAI require for site elevation and coordinates? Site elevation must be accurate within 0.5 metres AMSL, WGS-84 coordinates must be accurate to 1/10th of a second, and overall position accuracy must be within 3 metres.
Can I use a Survey of India elevation certificate for my AAI NOC application? No. AAI does not accept site elevation and coordinate certificates issued by the Survey of India for NOC applications — the certificate must come from a licensed surveyor, architect, engineer, or AAI-empanelled surveyor.
How many coordinate points does AAI require for a plot? A minimum of four corner points, including the point nearest to the airport. Even a triangular plot requires a fourth coordinate on the side facing the airport.
Can I edit my site elevation data after submitting the NOCAS application? No. Once submitted, application data cannot be altered, which is why getting the survey and certificate accurate before filing is critical.
Does the survey only cover the plot, or also the proposed structure height? For building applications, the survey and declared height must also account for rooftop installations — water tanks, lift motor rooms, telecom masts, and lightning arresters — since AAI requires the total height including these attachments.
Regulatory reference: Site elevation and coordinate requirements, accuracy standards, and the prescribed certificate format are published by the Airports Authority of India on the official AAI NOCAS portal. Always confirm the current format and requirements for your specific application before filing.