Flight Reliability
UA 321 · United Airlines
Chicago → Phoenix (ORD–PHX)85% of its flights flew this route. The rest (PHL–ORD) are included in these numbers.
- 81%
- Arrive within 15 minutes
- 2 min
- Average arrival delay
- 0.4%
- Cancelled
- 5 min early
- Median arrival delay
Based on 242 historical flights. Data through May 2026.
What the data says
The 9 AM–12 PM departure wins.
UA 321 departing between 9 AM–12 PM arrived on time 83% of the time, versus 71% between 6–9 AM.
Friday is doing you no favors.
UA 321 arrived on time 91% of the time on Tuesdays and just 69% on Fridays. That gap is worth planning around.
A bit ahead of the ORD–PHX route.
UA 321 arrived on time 81% of the time, versus 75% across the ORD–PHX route.
Trending in the right direction.
UA 321 arrived on time 89% of the time over the last three months in the data, compared with 76% in the three months before that.
The breakdown
- Mon74%(35 flights)
- Tue91%(32 flights)
- Wed91%(32 flights)
- Thu83%(35 flights)
- Fri69%(35 flights)
- Sat81%(36 flights)
- Sun83%(35 flights)
- 6–9 AM71%(35 flights)
- 9 AM–12 PM83%(205 flights)
Nov 83% → May 95% on time
| Month | On-time percentage | Flights |
|---|---|---|
| November 2025 | 83% | 30 |
| December 2025 | 66% | 44 |
| January 2026 | 69% | 36 |
| February 2026 | 93% | 28 |
| March 2026 | 87% | 47 |
| April 2026 | 83% | 30 |
| May 2026 | 95% | 20 |
- Departures on time
- 83%
- Diverted
- 0.4%
- Flights flown
- 240
- Months covered
- 8
Same route, other flights
Keep nerding
Based on 242 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.