Based Aircraft Defined!

by Hal Davis
WisDOT Bureau of Aeronautics

By their very nature, aircraft are commonly on the move. Sure, most aircraft have one airport they call “home,” but others may share time between multiple airports. In the Midwest, occasionally an aircraft owner will move their aircraft to a warmer climate during the winter months. Other times, an aircraft owner may have a hangar elsewhere, but spend the majority of his or her time “Up North” when the weather is good.

The Federal Aviation Administration (FAA) defines a “based aircraft” as an aircraft that is operational and air worthy, which is based at a specific facility for a majority of the year. It sounds simple enough, but in reality, applying that definition can be complicated. Fortunately, the Wisconsin Bureau of Aeronautics is here to help!

For airports in the FAA National Plan of Integrated Airport Systems (NPIAS), the number of based aircraft can affect airport classification and can factor into eligibility for airport improvement projects. Historically, airport managers were responsible for counting the number of based aircraft and reporting the totals to FAA and state inspectors. These totals would then show up on the airport’s master record form, also known as the “5010.” At the time, little guidance was provided on how the based aircraft numbers should be determined and there was no method of validating the counts. As a result, based aircraft counts were often unreliable.

To increase the accuracy of the data, FAA moved the process online. Today, is home to FAA’s National Based Aircraft Inventory Program. Here, operators of non-primary, NPIAS airports use tail numbers to report based aircraft at their airport.

If you are an operator of a non-primary NPIAS airport, make sure someone is reporting your based aircraft on

To get access, go to
Click ‘Login Support’
Fill out the required information
Click Send

The FAA will process your request and send you your login credentials once authorized.

Once logged in, it’s a simple process to add aircraft with the “Add Aircraft” button. Aircraft can also be deleted or edited after they are added. Upon entering a new aircraft, the site will check to see if the tail number is found in the FAA’s Aircraft Registration Database and then, based on the information in the Aircraft Registration data, provide the type (single-engine, multi-engine, jet or helicopter) automatically. Ultralights and military aircraft without tail numbers can also be listed.

The website will also check to see if the tail number has been reported by another airport. Tail numbers that are reported by more than one airport are considered to be duplicates and are excluded from the based aircraft counts of either facility. Although FAA recognizes there are valid reasons for some duplication of aircraft, they believe it is most often caused by outdated aircraft lists. However, airport operators are still encouraged to report tail numbers for all aircraft that they believe spend the majority of their time based at their airport. If a tail number is found to be a duplicate, both airports are encouraged to provide comments on why the aircraft should be considered as based at their airport.

After the initial list of aircraft are entered into, keeping the list up to date should take minimal time and effort. Individual aircraft can be removed and added as they come and go. While FAA recommends that airport operators update their aircraft list on at least once per year, I would recommend that you make changes to the list as they occur.

In 2010, FAA conducted a review of all general aviation airports in the NPIAS known as the ASSET study. FAA has plans to update this study in 2016. It is expected that based aircraft will continue to be a significant component to the study. Therefore, it is highly recommended that general aviation airports ensure that their based aircraft lists are entered and up to date on by spring 2016, so the new ASSET study includes the current based aircraft count at your airport.

If you have any questions about based aircraft or, please contact Mark Pfundheller at 608-267-5272 or

This entry was posted in Aircraft, Columns, Columns, Dec2015/Jan2016, Wisconsin Aeronautics Report and tagged , , , , . Bookmark the permalink.

Leave a Reply