The great thing about working in commercial real estate is that you never stop learning. Earlier this year I learned about Accident Potential Zones (APZs), and just this month I learned about Runway Protection Zones (RPZs). They are out there, but as I learned this year, you have to hunt for them because they may not show up in normal due diligence.

Eliza Solender

Our client purchased a great property in Fort Worth for a new school. The client is a sophisticated buyer and knows how to do its due diligence. With its specific use permit in hand and its building permit properly posted, they did their environmental remediation and began renovation of the building. There appeared a positive story in the paper about the site of the new school. The positive article was followed by a telephone call from Carswell Air Force Base: “We need to talk.”

The site of the new school is a considerable distance from Carswell, but it is still in the Accident Potential Zone of the runway. No one at the City of Fort Worth was aware of this. They were as shocked as our client. The City of Fort Worth has since passed a zoning overlay that shows the APZs for Carswell—they go in both directions from the runway—so future buyers will know in advance. Unfortunately for our client, it is sitting with a building that it can’t use, and must find a new location.

In April, we began a search for a new school site for another client. We found a site that appeared to be perfect. However, several parents on the real estate committee expressed concern that planes were flying very low over the site as they approached a nearby small, civilian airport. Beware of “APZs” we thought! The school retained a zoning consultant and asked them to investigate whether the site is in the Accident Potential Zone for the airport.

We also did our own research. Calls to the FAA and the airport did not help. No one seemed to know what we were talking about. Through online research, we came upon a HUD document (yes, a HUD document) entitled “Siting HUD-Assisted Projects in Accident Potential Zones—Military Airfields and Civilian Airports.”

In this two-page document we found what we needed. First, a definition: “The area of each end of the runway(s) where aircraft accidents are most likely to occur.” And then, the statement that enabled both us and the zoning consultant to use the right language with the civilian airport: “Civilian aviation calls it the Runway Protection Zone (RPZ), and the military services call it the Accident Potential Zone (APZ).”

We also learned from this HUD document that the length of the APZ for military air stations is 15,000 feet, and the length of the RPZ for civilian airports is a maximum of 2,500 feet.

A call back to the civilian airport with the question about the Runway Protection Zone for the airport resulted in a quick response: the Master Plan of the Airport. It shows the RPZs.

If you find yourself doing research near an airport, also ask for the Noise Contour Map. Like the APZs and RPZs, the noise levels also affect the allowed use of the property.

Ideally, airports would contact local governments and ask them to add to their zoning maps the areas affected by the APZs and RPZs, as Fort Worth has now done. But apparently this is rarely the case.

Have you learned something new lately?

Eliza Solender is president of Solender/Hall, Inc.

This article was originally posted in DMagazine Commercial Real Estate