About 1 in 9 UA 4309 flights from Houston arrived 15+ minutes late, diverted or cancelled over the past year (12%); 0.0% were cancelled. The typical flight landed 13 minutes early.
UA 4309: IAH → BRO
Scheduled to leave Houston at 8:30 p.m. local time, operated by CommutAir as C5 4309. Over the past year it arrived on time 88% of the time (146 flights), in line with other UA flights on the route at that hour (88%). Last seen in the data Aug 31, 2026.
Usually United Airlines's last flight of the day from Houston to Brownsville (100% of days). United Airlines's last IAH–BRO flight was cancelled 0.5% of the time, against 0.7% for its earlier ones. If it's cancelled, the next United Airlines flight is usually around 10:00 a.m. the next morning.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 23 | 87% |
| Tuesday | 22 | 91% |
| Wednesday | 22 | 91% |
| Thursday | 22 | 91% |
| Friday | 22 | 91% |
| Saturday | 12 | — |
| Sunday | 23 | 83% |
Why it was late
All flights IAH → BRO · Connecting off UA 4309? Check the risk
Questions
How often is UA 4309 from IAH to BRO late?
United Airlines 4309 from Houston, TX to Brownsville, TX arrived 15 or more minutes late, was diverted or was cancelled on 12% of 146 scheduled flights between September 2025 and August 2026. 0.0% 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.