Original DOT delay-reporting rule (2002)
DOT regulations at 14 CFR 234.4 began requiring airlines to report the cause of every delay of 15 minutes or more and every cancellation. The system used five categories: Air Carrier, Extreme Weather, National Aviation System, Security, and Late Arriving Aircraft.
Airlines began filing monthly cause data that the DOT shared with the public.
The Air Carrier category defined what counted as an airline's fault for 24 years, shaping which disruptions triggered amenity obligations.
The 2026 rule adds a sixth category and narrows the airline-controlled definition for the first time since this system began.
