Southwest Airlines arrived on time just 68.9% of the time in October — last place among the ten North American carriers tracked by aviation analytics firm Cirium, and a dip of more than two points from its own September figure. It was also nearly seven points behind Air Canada, the next-worst performer, and roughly 18 percentage points behind Delta, which topped the table at 86.86% on-time and posted a tiny 0.24% cancellation rate.

What makes October notable is that Southwest lost its usual safety net. For months, the airline's weak punctuality was softened by the fact that it cancelled fewer flights than anyone else — late, but reliably getting you there. In October, Delta, United and even low-cost rival Frontier cancelled a smaller share of flights (Frontier at 0.38%, Delta at 0.24%, United at 0.31% versus Southwest's 0.51%). Southwest was also down from 75.5% on-time in October last year.

Management isn't pretending otherwise. On the October 22 earnings call, COO Andrew Watterson said the problem sits mostly in delays of 15 to 45 minutes, with aircraft turnarounds starting well and then bleeding time at the end. CEO Bob Jordan has admitted poor punctuality is pushing up costs, partly through misconnected passengers — a real issue on an airline built around fast turns and quick connections.

Fixes are coming, just slowly. From November, gate agents get more power over bag-checking (a bigger workload now that checked bags carry fees and more people bring bags onboard) and can close flights from an iPad at the aircraft door. A rejigged flight schedule follows in January.

Elsewhere on the board: Delta ended WestJet's five-month run at the top, United narrowed Delta's lead to 2.80 points, and JetBlue staged the biggest comeback — from 63.85% on-time in August to 82.27% in October, with cancellations collapsing from 5.09% to 0.57%. American improved but slipped to sixth, falling further behind both big rivals. On airports, six US hubs made Cirium's global top 20 for on-time departures: Minneapolis–St. Paul, Washington Dulles, Detroit, Salt Lake City, Newark (yes, Newark) and Atlanta. Four are Delta hubs, two are United's; no American hub qualified.

Why should holiday flyers care? If you're weighing connecting itineraries on similar fares, these gaps are worth real money and real stress: Delta was nearly 18 points more likely than Southwest to get you to the gate within 15 minutes of schedule in October. The rankings shift seasonally with weather, but Southwest's slump has now lasted several months, and its turnaround plan won't fully land until January schedules change. If a tight connection is on the cards this winter, booking the more punctual carrier — or a longer layover — is the safer bet.