Understanding Your Airport's NPIAS Classification
Almost every federal planning conversation about a public-use airport starts with one question: is the airport in the NPIAS, and if so, what is its category? An airport’s NPIAS classification determines whether it can receive federal grants at all, and shapes the scale of funding it can plan around. This is a planner’s overview of what the NPIAS is, the classification tiers it uses, how those tiers drive funding eligibility, and how to look up your facility’s category.
What the NPIAS is
The NPIAS — the National Plan of Integrated Airport Systems — is a report the FAA publishes for Congress that identifies the public-use airports considered significant to national air transportation. Because inclusion in the NPIAS is what makes an airport eligible for federal Airport Improvement Program (AIP) funding, the report functions as the gateway to most federal airport development dollars.
The FAA updates the NPIAS roughly every two years; the current edition is the NPIAS 2025–2029. For each included airport, the report lists the facility along with its role in the system and its estimated development needs over the five-year horizon. An airport that is not in the NPIAS is not eligible for AIP grants, regardless of its activity.
The classification tiers
The NPIAS sorts its airports into categories that describe how each one serves the national system. The first division is between commercial service airports, reliever airports, and general aviation airports.
Commercial service airports
A commercial service airport is a publicly owned airport that has scheduled passenger service and at least 2,500 annual enplanements (passenger boardings). Within this group:
- Primary airports have more than 10,000 annual enplanements. Primary airports are further sub-categorized by hub size, based on each airport’s share of total U.S. annual enplanements:
- Large hub — 1% or more of total U.S. enplanements.
- Medium hub — 0.25% up to 1%.
- Small hub — 0.05% up to 0.25%.
- Nonhub — more than 10,000 enplanements but less than 0.05%.
- Nonprimary commercial service airports have between 2,500 and 10,000 annual enplanements.
| Category | Enplanement share |
|---|---|
| Large hub | 1% or more |
| Medium hub | 0.25% to 1% |
| Small hub | 0.05% to 0.25% |
| Nonhub (primary) | > 10,000 enplanements, < 0.05% |
| Nonprimary commercial service | 2,500 to 10,000 enplanements |
Reliever airports
Reliever airports are high-capacity general aviation airports that the FAA has specifically designated to relieve congestion at busy commercial service airports and to provide improved general aviation access to the surrounding community. They give GA traffic somewhere to go other than a crowded primary airport.
General aviation airports
General aviation airports are the largest group in the NPIAS by count. These are airports with fewer than 2,500 annual enplanements that are not classified as relievers. To describe the very different roles these airports play, the FAA further categorizes nonprimary airports — which includes both general aviation and nonprimary commercial service airports — into ASSET roles: National, Regional, Local, Basic, and Unclassified. These roles come out of the FAA’s General Aviation Airports / ASSET studies and reflect the type and level of activity an airport supports rather than its enplanement count.
How classification drives funding eligibility
Classification is not just a label — it directly governs how much federal money an airport can plan around. The core rule is that only airports in the NPIAS are eligible for AIP grants. Beyond that threshold, the category determines the funding mechanism:
- Primary airports receive annual entitlement (apportionment) funds calculated from their number of enplanements — more enplanements generally means a larger entitlement.
- Nonprimary NPIAS airports receive nonprimary entitlements and also compete for discretionary AIP funds for larger or higher-priority projects.
Because hub size scales with enplanements, and category determines which entitlement an airport draws on, classification shapes both whether an airport is eligible and the scale of funding it can realistically program into a capital plan. This is why a planning study almost always states the airport’s NPIAS category up front.
How to find your airport's classification
An airport’s NPIAS classification is published in the NPIAS report itself — Appendix A lists every NPIAS airport with its category and role — and it is also reflected in FAA airport records. For day-to-day planning work, you generally need three facts: whether the airport is in the NPIAS, its commercial service / reliever / GA category, and (for primary airports) its hub size.
AvPlot joins the FAA NPIAS 2025–2029 dataset into its airport lookup, so when you pull an airport the hub category and NPIAS service level surface automatically alongside the runway and facility data — no separate cross-reference to the report required. That same classification then feeds the forecasting workflow, where the airport’s category determines which forecast components apply.
This article is a reference summary for planning use, not a substitute for the governing FAA text. Classifications, thresholds, and roles are drawn from the FAA NPIAS 2025–2029 Report to Congress (Appendix A) and the FAA General Aviation Airports / ASSET categorization. Always verify an airport’s current category against the latest NPIAS report and FAA airport records before issuing a planning product. See the full airport planning glossary or the AvPlot toolkit.