U.S. Bureau of Transportation Statistics, Airline On-Time Performance
Month x reporting-carrier x origin-airport operational reliability from the official BTS TranStats Airline On-Time Performance files (keyless monthly ZIPs, https://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=236; the DOT Part-234 reporting carriers (12 in recent months; Hawaiian/Spirit also report in the 2025 window months), top 120 US origin airports by scheduled departures). Each row: scheduled flights, cancelled/diverted/delayed/on-time counts (BTS definition: arrival delay >= 15 min = delayed; identity gate flights == ontime+delayed+cancelled+diverted on every row), punctuality rates, total arrival-delay minutes decomposed into the five BTS delay causes (carrier/weather/NAS/security/late-aircraft; global identity gate: causes sum to total delay minutes within 0.1%, measured residual -0.024% on the live 13-month window), cause shares, average delay per delayed flight, MoM on-time momentum (YoY for the latest month), a documented 0-100 reliability_score ranked within each month, top delay cause, and cancel-wave / improving / record-low flags. Units: counts, minutes, percents, pp changes; shares sum to 1. Caveats: BTS rejects <0.01% of carrier-submitted records with arithmetic errors; the latest 1-2 months can be revised as carriers re-file; delay causes are carrier-reported per BTS definitions. Coverage: United States, 2025-08 -> 2026-07 (trailing 12 months; BTS publishes with ~2 months lag). Provenance: keyless BTS TranStats downloads, U.S. public domain - cite the U.S. Department of Transportation, Bureau of Transportation Statistics. Primary key: (month, carrier_iata, origin). Cadence: refreshed monthly. Nullability: cause shares / avg delay null when a row has no delay minutes; yoy_pp_ontime only on the latest month. Sample use: filter origin='ORD' and month='2026-07-01' to compare carriers' reliability_rank out of Chicago O'Hare.
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