Carrier route record
UAMIA→SFO
United Airlines · Miami to San Francisco
- Flights
- 603
- Period
- September 2025 to August 2026
- Share of route
- 35%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on MIA to SFO sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 603 flights, with a median arrival 6 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate United on MIA to SFO from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
73.7%
Arrivals under 15 minutes late, of 600 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
0.17%
National rate is 1.89%
Whole route
70.7%
Every carrier on MIA to SFO, 1,740 flights
These figures cover 603 flights between September 2025 and August 2026. Beyond the headline rate, 11.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
United against every carrier on MIA to SFO
United flew 603 of the 1,740 flights on MIA to SFO, about 35% of it. Its 73.7% on time is 3 points better than the route as a whole, which runs 70.7%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 73.7% to American at 69.2%.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 603 | 73.7% | 74 min | 0.17% | C+ |
| American Airlines | 1,137 | 69.2% | 65 min | 0.88% | C+ |
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Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against half a point between the best and worst carrier.
- 5am–8am113 flights89.4%
- 8am–11am162 flights88.8%
- 11am–2pm1 flights—
- 2pm–5pm1 flights—
- 5pm–8pm326 flights60.5%
- 8pm–5am—
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 60.5% on time, against 89.4% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 326 flights scheduled in it.
Across the year
United on MIA to SFO through the year
October is the best month on the calendar at 88.2% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 62 flights.
Across the week, Tuesday is the strongest day at 88.6% on time and Monday the weakest at 64.5%, a spread of 24 points.
Arrival by arrival
How late United on MIA to SFO runs when it is late
United on MIA to SFO often beats the schedule: 186 of 600 completed flights, 31%, arrived 15 minutes or more early. The 158 late arrivals split 54 under half an hour, 38 between 30 and 60 minutes, and 66 an hour or more.
- 15+ min early186 flights31.0%
- Within 15 min256 flights42.7%
- 15–29 min late54 flights9.0%
- 30–59 min late38 flights6.3%
- 1–2 hours late37 flights6.2%
- 2+ hours late29 flights4.8%
Scale runs 0% to 100%.
Share of 600 completed flights by arrival against schedule.
A late pushback is often recovered here: of 192 departures that left 15 minutes late or more, 59 still arrived on time. 25 flights left on time and still arrived late.
The worst days
Worst days for United on MIA to SFO
The latest arrival of the period was on 3 January 2026, 16 hours 14 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 3 January 2026 | 16 hours 14 minutes | Carrier |
| 28 December 2025 | 4 hours 25 minutes | Carrier |
| 15 February 2026 | 4 hours 24 minutes | National Airspace System |
| 25 January 2026 | 4 hours 16 minutes | Carrier |
| 18 June 2026 | 4 hours 15 minutes | National Airspace System |
Delay causes
Why United runs late on this route
National Airspace System accounts for 45% of the 12,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%National Airspace System
- 33%Carrier
- 20%Late-arriving aircraft
- 2%Extreme weather
45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 5,237 minutes out of 12,000, against a national NAS share of 21%. The split is drawn from 11,676 reported delay minutes.
Cancellations are rare at 0.17%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
11.0% 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 2,585 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 return leg is a different operation and performs like one: it runs 77.9% on time across 604 flights, 4 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
One caution: this is a thin sample. 603 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 United on MIA to SFO
Put together: treat all of this as provisional. 603 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 73.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 600 completed flights over 12 months sit behind that.
Related
Where to go next
- MIA to SFO, every carrier
- United on SFO to MIA, the return leg
- American Airlines on MIA to SFO69.2%
- United Airlines network-wide record
- Miami International (MIA) delay statistics
- San Francisco International (SFO) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- How often a connection fails at the major US hubs
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.