Increasing air traffic demand and the need to reduce environmental impact have intensified the importance of quantitatively assessing Air Traffic Management (ATM) performance. Among the 23 KPIs defined by ICAO, KPI08 (Additional Time in Terminal Airspace) is a key metric for evaluating terminal-area efficiency; however, its calculated value depends on methodological choices that have not been sufficiently examined. This study examines calculation conditions for applying KPI08 to arrival flows at Tokyo International Airport and Narita International Airport, while maintaining international comparability. Using operational trajectory data, the study compares alternative conditions for the target airspace, entry-position classification, and reference-time estimation from the viewpoints of consistency with the KPI concept, stability, comparability, implementability, and interpretability. The results indicate that a 100NM circular airspace, eight- direction entry classification at 45° intervals, and reference times derived from actual flights with the shortest flight distances are appropriate calculation conditions for the two airports. The validity of the resulting KPI08 values is further supported through comparison with time adjustment estimated at the 100NM entry point using runway interval requirements.

This paper proposes a turbulence metric, the Laplace Turbulence Index (LTI), for evaluating short-timescale wind fluctuations associated with low-altitude operations of small aircraft and unmanned aerial vehicles. The LTI is defined as the scale parameter b(Δt) of a zero-mean Laplace distribution fitted to temporal wind-velocity increments, Δu(t;Δt) = u(t + Δt) - u(t), for a given time lag Δt. High-rate ultrasonic anemometer data obtained from two platforms were analyzed: a pole-mounted sensor used as a reference and a drone-mounted sensor hovering near the pole for near-collocated comparison. The increment distributions showed sharp central peaks and tails that were well approximated by the Laplace distribution over a range of mean wind speeds. The LTI values derived from the drone data agreed closely with those from the pole-mounted reference, and no clear systematic difference was found between the horizontal components. These results suggest that LTI is a simple and practical index for turbulence evaluation in both fixed-point and mobile ultrasonic wind measurements.