A refined model for identifying unavoidable portion of the impact of weather and other factors on airport operation

In this paper, we develop a refined model for estimating the unavoidable portion of the impact of weather, traffic demand, risk mitigation and other factors on airport arrival operations. The focus on the unavoidable portion allows us to dissect it into a set of factors that are either objectively difficult or impossible to overcome completely (bad weather, for instance), or are outside of Air Traffic Management (ATM) purview (such as airlines´ decisions on flight cancellations). Then the remaining portion of the impact that which could not be classified as ´unavoidable´ can be considered as a pool of opportunities for improving air traffic efficiency. We limit the scope to arrivals at the OEP34 airports as a means to test our methodology. Extending it to airport departures and, indeed, to a more holistic view of the National Airspace System, will be subject of future work. This paper considers both non-convective (surface) weather and convective weather in terminal and en-route airspace in terms of impact on an airport´s arrival capacity. Generating a credible estimate of the best achievable arrival rate for an airport under given weather conditions and comparing it with the actually achieved rate, as well as with the intended (scheduled) rate, is a key component to quantifying delays and costs that can be attributed to weather. This functionality is based on the software used for computing the well- established Weather Impacted Traffic Index (WITI) metric. Initial results show that the annualized unavoidable weather impact portion is estimated to be in the order of 35-55% of overall weather / traffic impact; 44% on average. Our estimate is in line with previously published assessments but is a result of a more detailed analysis of the contributing factors. Also, while previous analyses have concentrated on summer weather, our model is applicable year round.