About 1 in 4 UA 4939 flights from Ithaca arrived 15+ minutes late, diverted or cancelled over the past year (26%); 2.5% were cancelled. The typical flight landed 10 minutes early.
UA 4939: ITH → IAD
Scheduled to leave Ithaca at 6:00 a.m. local time, operated by CommutAir as C5 4939. Over the past year it arrived on time 74% of the time (364 flights), in line with other UA flights on the route at that hour (74%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 53 | 74% |
| Tuesday | 52 | 77% |
| Wednesday | 51 | 82% |
| Thursday | 52 | 75% |
| Friday | 52 | 67% |
| Saturday | 52 | 79% |
| Sunday | 52 | 65% |
Why it was late
All flights ITH → IAD · Connecting off UA 4939? Check the risk
Questions
How often is UA 4939 from ITH to IAD late?
United Airlines 4939 from Ithaca/Cortland, NY to Washington, DC arrived 15 or more minutes late, was diverted or was cancelled on 26% of 364 scheduled flights between September 2025 and August 2026. 2.5% were cancelled.
Flight numbers change. Figures cover flights with this airline, number and route only. "Likely range" is the 95% interval for the true on-time rate given the number of flights. This is history, not live status: check United Airlines for today's flight. Method.