Flight Reliability
UA 4939 · United Airlines
ITH → Washington (ITH–IAD)
67
Usually Fine
WanderNerd Reliability Score
- 80%
- Arrive within 15 minutes
- 28 min
- Average arrival delay
- 2.7%
- Cancelled
- 10 min early
- Median arrival delay
Based on 364 historical flights. Data through May 2026.
What the data says
Sunday scaries are real for this one.
UA 4939 arrived on time 84% of the time on Saturdays. On Sundays: 75%.
Ticking up lately.
UA 4939 arrived on time 77% of the time over the last three months in the data, compared with 73% in the three months before that.
The breakdown
- Mon80%(50 flights)
- Tue82%(50 flights)
- Wed84%(50 flights)
- Thu77%(51 flights)
- Fri76%(50 flights)
- Sat84%(51 flights)
- Sun75%(51 flights)
84%
May
Jun 90% → May 84% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 90% | 30 |
| July 2025 | 86% | 28 |
| August 2025 | 74% | 31 |
| September 2025 | 93% | 30 |
| October 2025 | 84% | 31 |
| November 2025 | 77% | 30 |
| December 2025 | 76% | 29 |
| January 2026 | 69% | 29 |
| February 2026 | 73% | 26 |
| March 2026 | 68% | 28 |
| April 2026 | 80% | 30 |
| May 2026 | 84% | 31 |
- Departures on time
- 82%
- Diverted
- 0.3%
- Flights flown
- 353
- Months covered
- 12
Same route, other flights
Keep nerding
Based on 364 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.