Schedule: a typical summer Saturday (the flights of Jul 25, 2026), re-dated. Real flights replace these once airlines file their FAA flight plans, usually about a day ahead.
UNITED · FLIGHT UA 2121SCHEDULED · TYPICAL SCHEDULE
Tomorrow
UA 2121 · DEN → GRR
departs 5:55 PM MT · arrives 10:35 PM ET
Forecast issued Fri 11:00 PM ET · 21h before departure
Odds over time
Arrive at GRR more than 15 minutes late?
20%chance · ±3 pts+4 pts · 24h
HOW SURE WE AREGood. The odds now lean mostly on firmed-up weather forecasts.
How late will it get to GRR?
On time or early
79%
15–30 min late
9%
30 min–1 hour late
4%
1–2 hours late
5%
Over 2 hours late
3%
Cancelled
<1%
Gate arrival compared with the scheduled arrival. The ranges add up to 100%.