Airport runway clear zones in a HUD environmental review

Subpart D of 24 CFR part 51 sets the policy that the Department of Housing and Urban Development (HUD) follows for projects in three kinds of zone: the Runway Clear Zone at a civil airport, the Clear Zone at a military airfield, and the Accident Potential Zone beyond it. In the first two, called the clear zones on this page, the policy is not to assist covered projects, with one exception. In the third it is to discourage them. Where HUD assistance goes to buying or selling an existing property in a clear zone, the buyer must be told and must sign for the notice.

Who the rule binds

Part 51's standards "shall apply to all HUD actions except where special provisions and exemptions are contained in each subpart" (24 CFR 51.4).

Covered. HUD programs giving assistance, subsidy or insurance for construction, for land development, for community development or redevelopment, or for other facilities and services meant to make land available for construction. Assistance that only makes land available depends on whether what is to be built would itself be acceptable under 51.303 (24 CFR 51.302(a)). Also substantial or major modernization and rehabilitation, and "any other program which significantly prolongs the physical or economic life of existing facilities" (24 CFR 51.302(b)).
Covered in an Accident Potential Zone only. A program that changes a facility's use to one no longer acceptable under 51.303(b), significantly raises the density or the number of people at the site, or introduces explosive, flammable or toxic materials (24 CFR 51.302(b)).
Not covered, except for the notice to a buyer. Programs "where the action only involves the purchase, sale or rental of an existing property without significantly prolonging the physical or economic life of the property" (24 CFR 51.302(c)).
Not covered. Research or demonstration projects without new construction or reconstruction, interstate land sales registration, and any action or emergency assistance to save lives, protect property or public health and safety, or clear debris (24 CFR 51.302(d)). Nor a project approved for assistance before the regulation took effect (24 CFR 51.305(a)).

For programs reviewed under 24 CFR part 58, the responsible entity's Certifying Officer approves actions in any of the zones. For all other HUD programs it is the Program Assistant Secretary in a clear zone, and the HUD approving official with authority over the project in an Accident Potential Zone (24 CFR 51.304).

What it asks

Which airports. A civil airport is "An existing commercial service airport as designated in the National Plan of Integrated Airport Systems" (24 CFR 51.301(c)), a plan the Federal Aviation Administration (FAA) prepares. The definition names no other kind of civil airport.
The zones. Runway Clear Zones and Clear Zones are "Areas immediately beyond the ends of a runway" (24 CFR 51.301(d)). An Accident Potential Zone is "An area at military airfields which is beyond the Clear Zone", and "There are no Accident Potential Zones at civil airports" (24 CFR 51.301(a)). The subpart prints no dimensions. It points to FAA regulation 14 CFR part 152 for civil airports, and to Department of Defense (DOD) Instruction 4165.57, 32 CFR part 256, for military airfields (24 CFR 51.301(a), (d)).
Policy in a clear zone. It is quoted below (24 CFR 51.303(a)(1)). The exception is a project "which will not be frequently used or occupied by people", assisted "only when written assurances are provided to HUD by the airport operator to the effect that there are no plans to purchase the land involved with such facilities as part of a Runway Clear Zone or Clear Zone acquisition program" (24 CFR 51.303(a)(2)).
The notice to a buyer. "In all cases involving HUD assistance, subsidy, or insurance for the purchase or sale of an existing property in a Runway Clear Zone or Clear Zone", HUD, or under part 58 the responsible entity or recipient, shall tell the buyer three things: the property is in such a zone; what that location implies; and that the airport operator may later acquire it. "The buyer must sign a statement acknowledging receipt of this information" (24 CFR 51.303(a)(3)).
The notice under part 58. Part 58 sets the notice among its other requirements (24 CFR 58.6(d)). The responsible entity must address those in its Environmental Review Record (ERR), and meet them where applicable, "regardless of whether the activity is exempt under § 58.34 or categorically excluded under § 58.35(a) or (b)" (24 CFR 58.6).
Policy in an Accident Potential Zone. It "is to discourage the provision of any assistance, subsidy or insurance for projects and actions in the Accident Potential Zones". To be approved, a project must generally agree with what a land use compatibility chart in DOD Instruction 4165.57 recommends (24 CFR 51.303(b)).
Whose zones count. The only zones recognized are those the airport operators provide, defined under the FAA regulations or the DOD instruction. Data on the dimensions of Runway Clear Zones at civil airports "shall be verified with the nearest FAA Airports District Office before use by HUD" (24 CFR 51.305(b)).
The record. A decision to approve a project in any of the zones must be documented in the environmental assessment or, where none is required, in the project file (24 CFR 51.305(d)).

What it means for the Phase I and the consultant

The rule turns on these facts: whether the site lies in a zone the airport operator provides; whether the airport is a civil airport as defined or a military airfield; what the HUD action is; and whether people will frequently use or occupy the project.

ASTM E1527-21, the standard for the Phase I Environmental Site Assessment, is about releases of hazardous substances and petroleum products (E1527-21, 1.1, 1.1.1), and nothing in it asks about runways or their zones. Its site visit notes the current uses of adjoining properties and the surrounding area (E1527-21, 9.4.3, 9.4.5), so an airport may appear in a Phase I as a neighbor or a nearby use. Whether the site is inside a zone comes, under the rule, from the airport operator's data (24 CFR 51.305(b)).

The subpart does not say how often is frequently, or what significantly prolongs a facility's life. Those readings, and each approval, rest with HUD or the responsible entity.

What the rule says

HUD policy is not to provide any assistance, subsidy or insurance for projects and actions covered by this part except as stated in § 51.303(a)(2) below.

24 CFR 51.303(a)(1), edition revised as of April 1, 2025

This page is general reference for environmental professionals. It does not review any project. The regulation is the authority, and the determinations of HUD or of the entity responsible for the review govern.