Flight profile · United Airlines
UA1665
San Francisco (SFO) to Boston (BOS) · scheduled 11:25 PM – 8:08 AM
How UA1665 performs
1,014 operations, 2023-07-01 to 2026-06-30.
UA1665 arrived on time 81.5% of the time, against 78.2% for all SFO → BOS flights — this specific departure is 3.3 percentage points better than the route as a whole. Against United Airlines’s own flights on this route it is 2.2 points better.
Source: US DOT Bureau of Transportation Statistics · 1,014 operations between 2023-07-01 to 2026-06-30
Against the rest of the route
| On time | Cancelled | Median delay | Severe | Flights | |
|---|---|---|---|---|---|
| UA1665 | 81.5% | 1.18% | -8 min | 4.8% | 1,014 |
| United Airlines on SFO → BOS | 79.3% | 0.99% | -8 min | 8.3% | 5,334 |
| All SFO → BOS flights | 78.2% | 0.95% | -7 min | 8.3% | 13,718 |
Source: FlyerIntel analysis of US DOT BTS data · 2023-07-01 to 2026-06-30
By day of week
Does UA1665 run worse on particular days?
Tuesday is historically the most reliable day and Sunday the least, a gap of 12.4 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · 2023-07-01 to 2026-06-30 · Days with fewer than 120 operations are not scored.
Other routes UA1665 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| ONT→SFO Ontario to San Francisco | 2026-03-05 – 2026-05-20 | 71 | — |
| ATL→SFO Atlanta to San Francisco | 2026-02-12 – 2026-03-04 | 18 | — |
| SEA→SFO Seattle to San Francisco | 2026-01-07 – 2026-02-11 | 24 | — |
| SBA→SFO Santa Barbara to San Francisco | 2025-12-18 – 2026-01-05 | 15 | — |
| MSY→SFO New Orleans to San Francisco | 2025-05-22 – 2025-10-25 | 157 | 73.7% |
| PHX→SFO Phoenix to San Francisco | 2025-03-06 – 2025-05-21 | 48 | — |
| SNA→SFO Santa Ana to San Francisco | 2024-12-19 – 2025-01-06 | 19 | — |
| IND→SFO Indianapolis to San Francisco | 2024-08-19 – 2024-12-02 | 61 | — |
Because the same number has served different journeys, the statistics above describe only the route UA1665 currently operates. Blending them would produce an average of two different flights.
Data and methodology
Calculated by FlyerIntel from 1,014 records of UA1665 operating SFO → BOS, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.