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Making It Count

How Aircraft Transponder Signals Take the Guesswork Out of Counting Non-Towered Airport Operations

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“Many of the things you can count, don’t count. Many of the things you can’t count, really count.”— Albert Einstein

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The ATCs of 1–2–3s

Current counting methods for non-towered airports varies in both accuracy and reliability.

Let Me Count the Ways

You Can Count On It

(Left) Pole-mounted Version II device installed at Terre Haute Regional Airport (KHUF) for data collection at a towered airport. (Right) Stand-alone Version II device installed at Indianapolis Executive Airport (KTYQ) for data collection at a non-towered airport.
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The majority of GA aircraft are now equipped with ADS-B. However, there is a substantive share of GA aircraft that don’t operate in rule airspace that still have only Mode C transponders. This project uses an inexpensive ground-based radio receiver to monitor both Mode S and Mode C data. Image courtesy of PEGASAS

The Final Countdown

Jennifer Caron is FAA Safety Briefing’s copy editor and quality assurance lead. She is a certified technical writer-editor in the FAA’s Flight Standards Service.
This article was originally published in the September/October 2021 issue of FAA Safety Briefing magazine.
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Official FAA safety policy voice for general aviation. Part of the national FAA Safety Team (FAASTeam).