About 1 in 8 UA 1721 flights from San Francisco arrived 15+ minutes late, diverted or cancelled over the past year (13%); 0.3% were cancelled. The typical flight landed 11 minutes early.
UA 1721: SFO → KOA
Scheduled to leave San Francisco at 8:10 a.m. local time. Over the past year it arrived on time 87% of the time (365 flights), in line with other UA flights on the route at that hour (87%). Last seen in the data Aug 31, 2026.
Month by month
By day of week
| Day | Flights | On time |
|---|---|---|
| Monday | 53 | 91% |
| Tuesday | 52 | 88% |
| Wednesday | 52 | 87% |
| Thursday | 52 | 85% |
| Friday | 52 | 85% |
| Saturday | 52 | 87% |
| Sunday | 52 | 88% |
Why it was late
All flights SFO → KOA · Connecting off UA 1721? Check the risk
Questions
How often is UA 1721 from SFO to KOA late?
United Airlines 1721 from San Francisco, CA to Kona, HI arrived 15 or more minutes late, was diverted or was cancelled on 13% of 365 scheduled flights between September 2025 and August 2026. 0.3% 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.