Estimation of the instantaneous air count of general aviation aircraft flying under visual flight rules

This paper presents preliminary estimates of the instantaneous aircraft count (IAC) of general aviation (GA) aircraft flying under visual flight rules (VFR). Separate estimates for each of the following sub-categories of VFR flights are made from available data. (1) Itinerant GA flying under formal VFR flight plans. (2) Itinerant GA with no flight plans of any type. (3) Local GA. An itinerant aircraft is defined to be one whose origin and destination airports are different. A local GA is primarily one doing touch and go runway operations at an airfield. All estimates are generated by new mathematical models which utilize sampled field data. The IAC data of all GA come from towered and non-towered air fields and are tabulated by Air Route Traffic Control Center (ARTCC), and by type of flight plan (IFR, VFR, no flight plan), although this paper willdeal only with last two categories of flight plan. General aviation with no flight plans constitute most of the aircraft in the air at any one time. The basic approach has been: (1) data sampling instead of census; (2) statistical estimates to infer data not sampled; and (3) data validation. The IAC of itinerant GA-VFR over the continental United States is estimated to be roughly 13,000, which is about 8% of all registered GA aircraft. The IAC of local GA is about 7% of the itinerant count. Comparison of these estimates with other sources of information indicate that they are fairly reasonable. A point of major importance in the overall approach is that aircraft activity and flight characteristics are similar in similar regions, thereby drastically reducing data collection costs and data processing. Predictive techniques are also facilitated.