Flight history · Aug 2025 – Jul 2026 · US DOT on-time records
UA 521 · Atlanta (ATL) → Houston (IAH)
Sold by United. Still flying: 1 of the last 56 days.
Arrives on time83%within 15 minutes, of 88 flights
Cancelled0.0%of scheduled flights
An hour or more late9%of flights that operated
When late, on average98 minlate, among flights 15+ min late
Schedule
Typical times in the Jun 6 – Jul 31, 2026 schedule, local at each airport (Houston is 1 h behind Atlanta).
- Leaves ATL
- 16:04
- Arrives IAH
- 17:25
- Flight time
- 2h 21m
- Days flown, last 8 weeks
- 1 of 56
Each square is a day, Sat Jun 6 to Fri Jul 31, two weeks per row (each column is the same weekday); filled = flew.
How late it arrives
Share of flights that operated arriving more than this late.
Horizontal: minutes late at arrival (0 to 3 hours). Vertical: share of flights later than that.
Its hour at ATL
All flights leaving Atlanta (ATL) at 4–5 pm, wherever they’re going: 73% left within 15 minutes and 1.7% were cancelled (22,354 flights in the year). Other United flights on this route →
Upcoming forecasts
This flight isn’t in our published forecasts for the next few days.