The National Plan of Integrated Airport Systems
The FAA maintains a planning document called the National Plan of Integrated Airport Systems, or NPIAS, that identifies the airports considered necessary to support the national air transportation system. The current plan (2025–2029) includes approximately 3,300 existing and proposed airports across the United States and its territories.
Being included in the NPIAS matters for one critical reason: it is a prerequisite for receiving federal airport development grants through the Airport Improvement Program (AIP). If your airport is not in the NPIAS, it is not eligible for AIP funding. If it is in the NPIAS, you have access to federal grants — but you also accept the obligations that come with them.
The United States has roughly 19,000 landing facilities of various types, but only about 5,000 are open to the public. Of those, the approximately 3,300 in the NPIAS are the ones the FAA has determined are significant to national air transportation. The rest — private strips, heliports, and facilities not meeting NPIAS criteria — operate outside the federal grant framework.
NPIAS inclusion is not permanent. The FAA updates the plan periodically, and airports can be added or removed based on changes in activity levels, community need, and the airport's role in the system. If your airport's activity drops significantly or the sponsor fails to maintain the facility, removal from the NPIAS — and loss of AIP eligibility — is a real possibility.
How the FAA Classifies Airports
The FAA groups NPIAS airports into categories based on the type and volume of aviation activity they support. Understanding which category your airport falls into helps you benchmark against similar facilities, understand your AIP entitlement level, and communicate your airport's role to stakeholders.
Commercial Service Airports
These are publicly owned airports that receive scheduled passenger service and have at least 2,500 passenger boardings (enplanements) per year. Commercial service airports are further divided by enplanement levels into primary airports (10,000 or more annual enplanements) and non-primary commercial service airports (between 2,500 and 9,999). Primary airports are further broken down into large, medium, small, and non-hub categories based on their percentage of total U.S. enplanements.
If your airport has scheduled commercial service, these classifications drive your AIP entitlement formula — larger hubs receive significantly more in annual entitlement funds.
General Aviation Airports
The vast majority of NPIAS airports — roughly 88 percent — are classified as general aviation airports. These fields do not have scheduled commercial service (or have fewer than 2,500 annual enplanements) and serve a range of activities including flight training, agricultural aviation, business travel, recreational flying, emergency medical services, and aerial firefighting.
The FAA further categorizes GA airports based on their role in the system:
| GA Category | Role | Typical Characteristics |
|---|---|---|
| National | Support national and state economies by connecting communities to national and global markets | Long runways, instrument approaches, jet traffic, high based aircraft counts |
| Regional | Support regional economies and serve relatively large geographic areas | Moderate to long runways, instrument approaches, a mix of piston and turbine traffic |
| Local | Supplement local communities' access to the national airport system | Shorter runways, may or may not have instrument approaches, primarily piston aircraft |
| Basic | Provide access to the national airport system for communities that would otherwise be remote | Minimum infrastructure, may be turf runways, limited services, low based aircraft counts |
| Unclassified | Not yet categorized or insufficient data for classification | Varies |
Your GA classification affects your AIP entitlement. Non-primary airports in the NPIAS receive a minimum annual entitlement of $150,000, provided the airport sponsor has submitted an acceptable capital improvement plan to the FAA. The practical significance: even a small Basic-category airport can access federal funds for eligible projects.
Part 139 vs. Non-Part 139: What This Means for You
Title 14 of the Code of Federal Regulations, Part 139, establishes certification standards for airports that serve scheduled air carrier operations using aircraft with more than nine passenger seats. If your airport provides this type of service, you are required to hold an FAA Airport Operating Certificate and comply with the detailed operational, safety, and training requirements in Part 139.
If your airport does not serve scheduled air carriers with aircraft above the nine-seat threshold, you are a non-Part 139 airport. This is the case for the vast majority of GA airports in the country.
What Non-Part 139 Status Does Not Mean
It is a common misconception that non-Part 139 airports are unregulated. That is not accurate. While you are not subject to the specific operational certification requirements in Part 139, you are still bound by several categories of federal, state, and potentially local obligations:
- FAA Grant Assurances — If your airport has ever accepted AIP funds, you are bound by a set of 39 grant assurances covering everything from maintaining the facility in safe condition to prohibiting revenue diversion. These obligations persist for the useful life of the funded improvement, often 20 years or more. (This is covered in depth in Chapter 2.)
- State Licensing — Many states have their own requirements for public-use airports, which may include periodic inspections, minimum standards for runway condition and lighting, and zoning protections.
- 14 CFR Part 77 — Airspace obstruction standards apply to all airports. You have an obligation to protect the airspace around your field.
- Environmental Regulations — Federal and state environmental laws apply to fuel storage, stormwater management, wildlife management, and noise, regardless of certification status.
Contact your state's aeronautics division or department of transportation aviation office to get a clear picture of state-level requirements. These agencies are also valuable partners for technical assistance, grant programs, and advocacy on behalf of your airport.
Determining Your Airport's Classification
If you are not sure how the FAA classifies your airport, the simplest approach is to look it up in the current NPIAS report, available on the FAA's website. The report lists every NPIAS airport along with its state, associated city, FAA site number, and category/role classification.
You can also check the FAA's Airport Data and Information Portal (ADIP) or contact your FAA Regional Airports Division or your state aeronautics agency. These offices can confirm your NPIAS status, your current classification, and your AIP entitlement eligibility.
Why This Matters Day to Day
Your airport's classification is not just a bureaucratic label. It shapes the practical reality of how you manage your field:
- Funding access — NPIAS inclusion determines AIP eligibility. Your specific category influences your entitlement level and the types of projects you can fund.
- Regulatory requirements — Part 139 certification triggers a detailed set of operational obligations. Non-Part 139 airports operate under a different (but still real) set of rules, primarily driven by grant assurances and state law.
- Stakeholder expectations — Your classification helps frame conversations with local government, tenants, and community members about what level of infrastructure and services are appropriate for your facility.
- Benchmarking — Comparing your operations, revenue, and staffing to airports in the same NPIAS category gives you more meaningful data than comparing against all airports regardless of size.
The chapters that follow build on this foundation. Chapter 2 covers the federal obligations that come with NPIAS inclusion and AIP funding — the grant assurances that every airport manager at a federally-obligated airport needs to understand.