Regime-Aware Conformal Uncertainty Quantification for Irregular ADS-B Trajectories in Terminal Airspace

Automatic Dependent Surveillance-Broadcast (ADS-B) receiver streams contain irregular updates and within-trajectory gaps that may reflect forecast uncertainty. We evaluate reception-conditioned residual calibration using established global and Mondrian split conformal methods. The KLAF archive contains 99,736,221 observations from 5161 aircraft over 463 observed dates; repeated experiments use 1,001,738 observations from 276 complete aircraft–days. Training-selected reported-state constant velocity achieves a test mean horizontal distance error (MDE) of 0.848 km and root-mean-square error of 1.385 km on 220,061 common predictor cases. A finite-adjacent-heading calculation labels 99.97% of these cases; stable and maneuvering MDEs are 0.578 and 1.993 km. On 220,040 identical raw forecast cases, causal selective preprocessing increases MDE by 0.0054 km (95% day-cluster interval 0.0045–0.0061). At 90% target coverage, nominal and degraded reception radii are 2.974 and 3.666 km, with a degraded-to-nominal ratio of 1.233 (95% interval 1.143–1.284). At 95%, the ratio is 1.175 (1.108–1.209). Degraded empirical coverage is 89.49% and 93.79%, respectively. Wider degraded radii persist across segmentation, reception-threshold, and motion-stratified analyses. These are empirical out-of-time results for eligible, matched forecasts from one selected terminal benchmark; chronological splitting and cluster resampling do not establish formal conformal validity under the observed dependence.