Flight number record
UA 2647
United Airlines · San Francisco to Boston
- Route
- SFO → BOS
- Departs
- 08:25
- Flights
- 335
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 2647, check with United Airlines.
UA 2647 lands a B, 5 points better than the national rate of 77.3%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 335 flights, with a median arrival 12 minutes early.
Set against the rest of the country, UA 2647's record is 5 points better than the US average of 77.3%. That gap is worth roughly 45 fewer late arrivals for every thousand flights.
Key figures
On time
81.8%
Arrivals under 15 minutes late, of 330 completed flights
Avg delay
88 min
Across delayed arrivals only, not all flights
Cancelled
1.19%
National rate is 1.89%
1 hour+ late
10.6%
National rate is 8.3%
These figures cover 335 flights between September 2025 and August 2026. Beyond the headline rate, 10.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 2647 flies
UA 2647 flies SFO to BOS without a single fixed slot. Its most common scheduled departure was 08:25, used on 177 of 335 flights, with 08:10 (75 flights) next.
- Departs 08:25177 flights52.8%
- Departs 08:1075 flights22.4%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 08:25 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and UA 2647 runs 2 points worse at 81.8%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
UA 2647 next to SFO to BOS
Every carrier on SFO to BOS combined arrived on time 74.5% of the time across 4,815 flights, so UA 2647 is 7 points ahead of it. United flew 1,939 flights on the same city pair under all its flight numbers, including this one, and those ran 78.5% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2647thin sample | 335 | 81.8% | 88 min | 1.19% | B |
| All United Airlines on SFO–BOS | 1,939 | 78.5% | 73 min | 1.08% | B |
| All carriers on SFO–BOS | 4,815 | 74.5% | 74 min | 1.81% | C |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 2647 quarter by quarter
Quarter by quarter UA 2647 held fairly steady: 77.2% in Oct–Dec 2025, 80.7% in Jan–Mar 2026, 85.6% in Apr–Jun 2026 and 86.8% in Jul–Sep 2026. A spread of 10 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 20257 flights—
- Oct–Dec 202592 flights77.2%
- Jan–Mar 202690 flights80.7%
- Apr–Jun 202690 flights85.6%
- Jul–Sep 202656 flights86.8%
Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2647 ranged from 75.5% on Thursday to 87.2% on Wednesday. With about 48 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 2647 runs when it is late
UA 2647 often beats the schedule: 146 of 330 completed flights, 44%, arrived 15 minutes or more early. When UA 2647 is late it tends to be very late: 35 of its 60 late arrivals were an hour or more behind, and 13 were two hours or more.
- 15+ min early146 flights44.2%
- Within 15 min124 flights37.6%
- 15–29 min late12 flights3.6%
- 30–59 min late13 flights3.9%
- 1–2 hours late22 flights6.7%
- 2+ hours late13 flights3.9%
Scale runs 0% to 100%.
Share of 330 completed flights by arrival against schedule.
11 of 59 late departures made up the time and arrived on time, 19% of them. 12 flights left on time and still arrived late.
The worst days
Worst days for UA 2647
The latest arrival of the period was on 27 December 2025, 8 hours 21 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in October 2025.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 27 December 2025 | 8 hours 21 minutes | Carrier |
| 25 September 2025 | 4 hours 48 minutes | National Airspace System |
| 26 October 2025 | 4 hours 6 minutes | Late-arriving aircraft |
| 30 October 2025 | 3 hours 59 minutes | Late-arriving aircraft |
| 13 October 2025 | 3 hours 51 minutes | National Airspace System |
Delay causes
Why UA 2647 runs late
National Airspace System accounts for 45% of the 5,252 delay minutes carriers reported here, and the remaining four split what is left.
- 45%National Airspace System
- 38%Late-arriving aircraft
- 18%Carrier
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 5,252 reported delay minutes here, that single category outweighs weather by 38 to one. The split is drawn from 5,252 delay minutes reported on UA 2647.
Cancellations sit at 1.19% against a national 1.89%, which is ordinary. Diversions add another 0.30%.
Connections and routes
What a delay on this flight costs
10.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 2,704 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The same number turns up on three other city pairs in the data, including LAX to SFO (115), ONT to SFO (24) and BOS to EWR (1), but none flew often enough under UA 2647 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SFO to BOS only.
One caution: this is a thin sample. 335 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking UA 2647
For a booking, read UA 2647 as 81.8% on time with 1.19% cancelled over 335 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SFO to BOS, every carrier and departure
- BOS to SFO, the return direction
- Delta Air Lines 400 on the same route88.5%
- JetBlue Airways 734 on the same route74.1%
- United Airlines 1665 on the same route83.7%
- JetBlue Airways 1734 on the same route66.2%
- United Airlines 1372 on the same route74.3%
- United Airlines 2356 on the same route63.0%
- San Francisco International (SFO) delay statistics
- Boston Logan International (BOS) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means United Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.