Flight Reliability
UA 2021 · United Airlines
Washington → San Juan (IAD–SJU)
93
Nerd Approved
WanderNerd Reliability Score
- 88%
- Arrive within 15 minutes
- 2 min early
- Average arrival delay
- 0.6%
- Cancelled
- 7 min early
- Median arrival delay
Based on 347 historical flights. Data through May 2026.
What the data says
Monday is the weak spot.
UA 2021 arrived on time 96% of the time on Wednesdays. On Mondays: 82%.
Better than the IAD–SJU route average.
UA 2021 arrived on time 88% of the time, versus 76% across the IAD–SJU route.
Better than the United Airlines network average.
UA 2021 arrived on time 88% of the time, versus 79% across the United Airlines network.
Trending in the right direction.
UA 2021 arrived on time 93% of the time over the last three months in the data, compared with 85% in the three months before that.
The breakdown
- Mon82%(49 flights)
- Tue92%(48 flights)
- Wed96%(47 flights)
- Thu90%(49 flights)
- Fri88%(49 flights)
- Sat84%(51 flights)
- Sun85%(52 flights)
100%
May
Jun 97% → May 100% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 97% | 30 |
| July 2025 | 84% | 31 |
| August 2025 | 74% | 31 |
| September 2025 | 77% | 13 |
| October 2025 | 94% | 31 |
| November 2025 | 87% | 30 |
| December 2025 | 81% | 31 |
| January 2026 | 86% | 29 |
| February 2026 | 89% | 27 |
| March 2026 | 90% | 31 |
| April 2026 | 90% | 30 |
| May 2026 | 100% | 31 |
- Departures on time
- 94%
- Diverted
- 0%
- Flights flown
- 345
- Months covered
- 12
Same route, other flights
Keep nerding
Based on 347 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.