About 1 in 8 UA 4821 flights from Houston arrived 15+ minutes late, diverted or cancelled over the past year (12%); 0.7% were cancelled. The typical flight landed 17 minutes early.
UA 4821: IAH → AMA
Scheduled to leave Houston at 9:30 a.m. local time, operated by CommutAir as C5 4821. Over the past year it arrived on time 88% of the time (287 flights), in line with other UA flights on the route at that hour (88%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 50 | 88% |
| Tuesday | 39 | 92% |
| Wednesday | 41 | 88% |
| Thursday | 49 | 88% |
| Friday | 49 | 92% |
| Saturday | 23 | 74% |
| Sunday | 36 | 89% |
Why it was late
All flights IAH → AMA · Connecting off UA 4821? Check the risk
Questions
How often is UA 4821 from IAH to AMA late?
United Airlines 4821 from Houston, TX to Amarillo, TX arrived 15 or more minutes late, was diverted or was cancelled on 12% of 287 scheduled flights between September 2025 and August 2026. 0.7% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check United Airlines for today's flight. Method.