Today: AS 388 at 08:13 is the safest bet, 14% chance of being 15+ min late; the others run 17–28%.

Safest bet today AS 388 SEA 08:13 → STL 14:02 · 14% chance 15+ min late · usually 86% on time Riskiest AS 672 SEA 13:07 → STL 18:53 · 28% chance 15+ min late

Against a calm day 20% average chance a nonstop arrives 15+ min late; 21% for the same flights on a calm-weather day

Every nonstop today

12-month record →

Ranked by the chance of arriving 15+ minutes late, with each flight’s on-time record over Aug 2025 – Jul 2026 beside it. Times are local. Pick a flight for its forecast. Click a column to sort.


AS 388 Alaska Flight history →	SEA 08:13	STL 14:02	14%	3%	0.2%	86%
AS 647 Alaska Flight history →	SEA 09:40	STL 15:29	17%	3%	0.2%	88%
AS 618 Alaska Flight history →	SEA 18:02	STL 23:50	19%	3%	0.5%	92%worse than usual
AS 672 Alaska	SEA 13:07	STL 18:53	28%	3%	0.5%	no record

How these are worked out. Each flight’s odds are our forecast for that day; flights of airlines we don’t forecast yet use their 12-month record and are marked. Makes the connection: the first flight’s 12-month lateness curve, scaled so its chance of arriving 15+ min late matches the day’s forecast, at the layover minus the 45-minute minimum (90 on separate tickets). Arrives on time: first flight not cancelled × connection made × second flight not cancelled × second flight within 15 minutes, each from the day’s forecast.

About this data: forecast odds from our model for Tue, Oct 6 (newest published update); 12-month records from US DOT on-time data, Aug 2025 – Jul 2026, all US airlines; regional flights count under the airline that sells them. JSON