Safety Analysis of General Aviation Runway Operations Ryan Dittoe Arjun H. Rao, Ph.D. Seth Young, Ph.D., A.A.E., CFI Introduction Findings Contributing Factors Rank Contributing Factor Percentage relative to contributing factors at all 349 airports 1 Procedures/Operations 6.98% 2 Direct taxiing access to runways from ramp area 17.99% 3 Taxiway intersections runway at other than a right angle 20.69% 4 Communication 5.21% 5 Unexpected holding position marking on parallel/entrance taxiway 60.00% 6 Two runway thresholds in close proximity 26.92% 7 Wrong runway events 6.33% 8 Other (Actions of someone else warranted an incursion) 7.81% 9 Signage 17.65% 10 Wide expanses of taxi pavements along a runway 5.66% General Aviation (GA) operations account for 96.8% of all active civil aircraft operations in the United States (US). Recent estimates by the Federal Aviation Administration (FAA) showed that the GA fatal accident rate has remained relatively unchanged between 2010 and 2015, with 1,566 fatal accidents accounting for 2,650 fatalities. The 2013 Joseph T. Nall report highlights the great variety of facilities available during GA operations––about 5,300 public-use and 8,000 private-use airports (in contrast to the approximately 600 large public-use airports used by commercial airlines). The bulk of published research on GA safety is focused on improving safety during flight. However, there is limited research on the safety of GA surface operations. Specifically, there is relatively little published research on GA runway incursions defined by the International Civil Aviation Organization (ICAO) as “Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle, or person on the protected area of a surface designated for the landing and takeoff of aircraft”. In this research, we seek to answer the following questions: Which airports frequently experienced runway incursions involving GA operations? What are the primary reasons (contributing factors) for these runway incursions? Can we learn more about GA runway safety by studying yearly trends? Table 2: Contributing factors at Top-10 airports shown as a percentage of those same contributing factors at all 349 airports with at least one reported incursion under FAR Part 91 GA Operations in 2011–2013 Table 2 shows the ten most frequently occurring contributing factors at the Top-10 airports with reported GA incursions in 2011–2013. The highlighted factors are specific to airfield geometry while the remaining factors are unique to alternate circumstances in the individual scenarios. Items like non-standard radio phraseology, control tower procedures, actions of others on the airfield, and non-standard placement of signage may also contribute to incursions. Figure 1: Distribution of all 349 airports with at least one reported incursion associated with FAR Part 91 GA itinerant operations in 2011–2013. The top-10 airports accounted for 9% of all GA incursions in 2011–2013. When we extend the range to include the top-50 airports, we found that 22% of the GA incursions were distributed across 40 airports; in other words, the top-50 airports accounted for 31% of all GA incursions. Similarly, the top-100 accounted for 53% of all GA incursions. Next, we ranked the airports by total number of runway incursions per 100,000 GA itinerant operations. Given this, we could categorize airports into “very high risk”, “high risk”, “medium risk”, and “low risk” groups. Rank Airport Code Total GA Incursions, 2011-2013 Total GA Itinerant Operations, 2011-2013 Incursions per 100,000 GA Itinerant Operations 1 JLN 26 35,344 73.56 2 VCT 11 25,676 42.84 3 BFM 16 39,233 40.78 4 NEW 37 95,758 38.64 5 VGT 53 168,513 31.45 6 BET 13,378 29.90 7 MLI 9 33,843 26.59 8 MHT 29,923 23.39 IDA 39,891 22.56 10 GCN 9,000 22.22 Future Research These findings can be used to generate a holistic analysis at target airports. We would like to understand what took place at the airports with changes in their rates of incursions; namely JLN, NEW, VGT, MLI, and MHT (50% increase or reduction in some years). This information could illustrate a more complete picture which will aid in determining appropriate proactive measures that promote safer airfields. Developing a predictive model to better determine risk at airports will enable pilots, airport staff, planners, and designers a better chance to mitigate hazards before they occur. Methodology We Analyzed historical GA accident and incident data between 2011–2013 from NTSB, ASRS, RWS, PDS, and VPDS databases. The dataset comprised of 10,945 events, which were accidents or incidents. We found a total of 3,425 runway incursions, of which 56.4% (1,932) involved FAR Part 91 GA operations. Next, we counted the number of incursions per year and ranked airports with at least one reported incursion (total 349 airports) according to a standard unit that normalized all events (per 100,000 GA itinerant operations). Table 1: Top 10 airports ranked by number of GA incursions per 100,000 GA itinerant operations in 2011-2013 Figure 2: Total incursions per year at each of the Top-10 airports Note that the number of incursions at some airports could be high because there is higher volume of GA itinerant operations at these facilities (e.g., VGT). In some cases, airports with relatively low number of GA itinerant operations have higher number of incursions (e.g., JLN). Figure 2 shows a three-year frequency trend for the top-ranked airports presented in Table 1. The fluctuation in frequency could be attributed to a number of causes. Our focus would begin with the ten illustrated above. These ranked higher than 339 other airports with incursions during 2011–2013. Acknowledgment This research was motivated by work performed by the authors through the FAA's Center of Excellence for General Aviation (PEGASAS), and the FAA's Airport Safety Database (ASD) Research project. The technical monitor is Lauren Collins. The views expressed in this paper are those of the authors and do not necessarily reflect those of the FAA. The information in this research does not constitute FAA Flight Standards or FAA Aircraft Certification policy.