Friday, October 9 · typical odds for a Friday (too early for a weather forecast) · issued Mon 12:00 PM ET · 7 nonstops

Fri, Oct 9 looks like a normal day here: all 3 nonstops are 9–15% likely to arrive 15+ min late.

Safest bet that day DL 5800 GRR 19:41 → DTW 20:45 · 9% chance 15+ min late · usually 93% on time Riskiest DL 3500 GRR 10:34 → DTW 11:33 · 15% chance 15+ min late · usually 81% on time

Every nonstop on Fri, Oct 9

12-month record →

Ranked by the chance of arriving 15+ minutes late (typical odds: the weather this date has had in past years), 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.


DL 5800 Delta flown by Republic Flight history →	GRR 19:41	DTW 20:45	9%	3%	0.7%	93%
DL 3885 Delta flown by SkyWest Flight history →	GRR 08:15	DTW 09:18	11%	7%	0.6%	91%
DL 3500 Delta flown by SkyWest Flight history →	GRR 10:34	DTW 11:33	15%	7%	0.6%	81%
DL 4885 Delta flown by Endeavor no forecast: 12-month record	GRR 05:30	DTW 06:30	15%	7%	1.2%	85%
DL 5473 Delta flown by Endeavor no forecast: 12-month record	GRR 12:10	DTW 13:13	29%	10%	1.9%	71%
DL 5511 Delta flown by Endeavor no forecast: 12-month record	GRR 17:55	DTW 18:59	30%	15%	6.1%	70%
DL 5390 Delta flown by Endeavor no forecast: 12-month record	GRR 14:35	DTW 15:38	33%	13%	0.0%	67%

How these are worked out. Each flight’s odds are our forecast for that day (typical odds until the weather forecast covers it); 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 Fri, Oct 9 (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