Evaluating Methods for Counting Aircraft Operations at Non-Towered Airports

Abstract

This report provides a thorough review of techniques and technologies for estimating aircraft operations at airports without air traffic control towers. The report documents the industryâs first comprehensive evaluation of the most common traffic estimation methods and is especially valuable to practitioners seeking to develop a statistically defensible estimate of aircraft activity for their non-towered airport. The research built on the results of ACRP Synthesis 4: Counting Aircraft Operations at Non-Towered Airports by reviewing recent literature and identifying new technologies. The research team then reached out to stakeholders to identify how operations data are used, confirm the criteria practitioners consider when selecting a counting method, and determine the most common counting methods used by the industry. Next, a testing program was conducted to evaluate the accuracy of three methods, including multiplying based aircraft by an estimated number of operations per based aircraft, applying a ratio of FAA flight plans to total operations, and expanding a sample count into an annual estimate through extrapolation. For the sampling method, the testing program also looked at the accuracy of different aircraft traffic counting technologies. The testing program involved installing counting systems at four airports for extended time periods to test their accuracy, reliability, and ease of use within the safety and operational constraints typically found at airports. The research also evaluated sampling plans and methods of expanding samples to produce estimates of annual activity. The research found that methods of estimating aircraft operations using ratios of based aircraft or instrument flight plans, while simple and inexpensive, could not be supported by the test results. Basing operations estimates on actual samples of activity produces results that are significantly more accurate and defensible, with the most accurate sampling approach based on four 2-week samples. Finally, the research found that the selection of a counting technology needs to consider the airfield layout and fleet mix, among other factors