Frequently Asked Questions  

How does NGS compute the Airport Reference Point (ARP) position?
Use this interactive ARP computation utility to compute the approximate geometric center of all usable runways at an Airport.

What are the specifications of the imaginary surfaces (Obstruction Identification Surface - OIS)?

Click the thumbnails or links to view the answers-

What is a PACS?         What is a SACS?         What is a CORS?         What is a HARN Station?

How clear should the area surrounding a PACS or SACS station be?    

How can I Access CORS Data?

How can I Retrieve a Survey Point Data Sheet?

How can I Compute Runway, Stopway, and Displaced Threshold Lengths using the NGS INVERSE3D program?

What is the UDDF format?

Go to NGS FAQ

Check out the Aeronautical Survey Program Slide Show

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