The Feb. 2019 issue of the DOT
Air Travel Consumer Report has full-year 2018 data for on-time performance and denied boarding.
https://www.transportation.gov/sites...ry2019atcr.pdf
Delta did pretty well in
on-time although Delta Connection lags mainline. DC still beat mainline UA/AA/WN however. (JetBlue and Frontier are wrecks.) The combined DL/DL Connection placed
#2 in on-time for the year behind Hawaiian.
This DOT report cites cancellations and causes for the month but not YTD, regrettably.
Involuntary Denied Boarding is statistically a non-issue on Delta flights - but boy, they do a lot of VDB.
Baggage handling is reported only by operating carrier. Delta mainline is better than the industry average. The three regional express carriers large enough to be reporting for this table are way behind mainline performance. Weight and balance issues? Less automation at small airports?
