Flight Reliability
UA 4959 · United Airlines
Greenville → Washington (GSP–IAD)
73
Usually Fine
WanderNerd Reliability Score
- 78%
- Arrive within 15 minutes
- 13 min
- Average arrival delay
- 1.9%
- Cancelled
- 4 min early
- Median arrival delay
Based on 314 historical flights. Data through May 2026.
What the data says
Sunday scaries are real for this one.
UA 4959 arrived on time 88% of the time on Tuesdays and just 68% on Sundays. That gap is worth planning around.
A bit behind the GSP–IAD route.
UA 4959 arrived on time 78% of the time, versus 83% across the GSP–IAD route.
Recent months have been rougher.
UA 4959 arrived on time 78% of the time over the last three months in the data, compared with 85% in the three months before that.
The breakdown
- Mon72%(47 flights)
- Tue88%(48 flights)
- Wed81%(47 flights)
- Thu81%(48 flights)
- Fri74%(49 flights)
- Sat82%(22 flights)
- Sun68%(44 flights)
72%
May
Jun 81% → May 72% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 81% | 26 |
| July 2025 | 64% | 28 |
| August 2025 | 71% | 31 |
| September 2025 | 81% | 26 |
| October 2025 | 77% | 31 |
| November 2025 | 73% | 22 |
| December 2025 | 73% | 15 |
| January 2026 | 95% | 20 |
| February 2026 | 88% | 24 |
| March 2026 | 77% | 31 |
| April 2026 | 85% | 26 |
| May 2026 | 72% | 25 |
- Departures on time
- 82%
- Diverted
- 1.0%
- Flights flown
- 305
- Months covered
- 12
Same route, other flights
Keep nerding
Based on 314 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.