Today: UA 3520 at 10:22 is the safest bet, 9% chance of being 15+ min late; evening flights run 15–25%.

Safest bet today UA 3520 SDF 10:22 → ORD 11:09 · 9% chance 15+ min late · usually 100% on time Riskiest UA 5929 SDF 17:50 → ORD 18:40 · 25% chance 15+ min late · usually 59% on time

Against a calm day 14% average chance a nonstop arrives 15+ min late; 17% 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. Dimmed: airlines we don’t forecast yet, shown with their 12-month record if they usually fly that weekday. 3 flights that already left today are not shown.


UA 3520 United flown by Republic Flight history →	SDF 10:22	ORD 11:09	9%	2%	0.1%	100%
AA 4704 American flown by Republic Flight history →	SDF 10:36	ORD 11:15	9%	2%	0.1%	96%
UA 3422 United flown by Republic Flight history →	SDF 07:15	ORD 07:56	9%	3%	0.1%	90%
YX 4492 Republic	SDF 10:15	ORD 11:02	9%	3%	0.1%	no record
UA 3696 United flown by Republic Flight history →	SDF 09:00	ORD 09:38	10%	3%	0.1%	95%
YX 3477 Republic	SDF 09:03	ORD 09:50	10%	3%	0.1%	no record
MQ 3580 Envoy	SDF 12:54	ORD 13:32	12%	3%	0.4%	no record
AA 4668 American flown by Republic Flight history →	SDF 17:18	ORD 18:05	15%	4%	0.2%	79%
UA 5629 United flown by SkyWest Flight history →	SDF 10:04	ORD 10:40	17%	5%	0.2%	55%
UA 5603 United flown by SkyWest Flight history →	SDF 14:10	ORD 14:50	21%	5%	0.2%	57%
OO 5834 SkyWest	SDF 13:52	ORD 14:29	21%	4%	0.2%	no record
UA 5929 United flown by SkyWest Flight history →	SDF 17:50	ORD 18:40	25%	7%	0.3%	59%
UA 4563 United flown by GoJet no forecast: 12-month record	SDF 19:55	ORD 20:40	23%	5%	6.4%	77%

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 Mon, Oct 5 (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