Flight number record
UA 737
United Airlines · Seattle to San Francisco
- Route
- SEA → SFO
- Departs
- 19:34
- Flights
- 362
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 737, check with United Airlines.
UA 737 draws a D+. Roughly one flight in two arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 362 flights, with a median arrival 3 minutes late.
The national on-time rate over the same period is 77.6%, so UA 737 runs 18 points behind the country as a whole. Across a thousand flights that is about 177 extra late arrivals.
Key figures
On time
59.9%
Arrivals under 15 minutes late, of 359 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.81%
1 hour+ late
13.9%
National rate is 8.1%
These figures cover 362 flights between July 2025 and June 2026. Beyond the headline rate, 13.9% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When UA 737 flies
UA 737 flies SEA to SFO without a single fixed slot. Its most common scheduled departure was 19:34, used on 69 of 362 flights, with 19:37 (63 flights) and 17:10 (37 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 19:3469 flights19.1%
- Departs 19:3763 flights17.4%
- Departs 17:1037 flights10.2%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 19:34 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and UA 737 runs 8 points worse at 59.9%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
UA 737 next to SEA to SFO
Every carrier on SEA to SFO combined arrived on time 65.6% of the time across 6,764 flights, so UA 737 is 6 points behind it. United flew 2,040 flights on the same city pair under all its flight numbers, including this one, and those ran 66.5% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 19 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 737thin sample | 362 | 59.9% | 68 min | 0.83% | D+ |
| All United Airlines on SEA–SFO | 2,040 | 66.5% | 71 min | 0.83% | C+ |
| All carriers on SEA–SFO | 6,764 | 65.6% | 59 min | 1.20% | C |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 737 quarter by quarter
UA 737 did not run the same all year. Its best quarter was Jan–Mar 2026 at 78.9% on time and its weakest Apr–Jun 2026 at 20.9%, a swing of 58 points on roughly 91 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202592 flights69.2%
- Oct–Dec 202589 flights71.3%
- Jan–Mar 202690 flights78.9%
- Apr–Jun 202691 flights20.9%
Scale runs 10% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, UA 737 did best on Tuesday at 76.9% on time and worst on Friday at 46.2%. Each day rests on about 52 flights, so a gap of 31 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 737 runs late
One category carries most of the weight here. National Airspace System accounts for 62% of the 9,735 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 62%National Airspace System
- 28%Late-arriving aircraft
- 7%Carrier
- 3%Extreme weather
62% 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 6,029 minutes out of 9,735, against a national NAS share of 21%. The split is drawn from 9,735 delay minutes reported on UA 737.
Cancellations are rare at 0.83%, below the national 1.81% 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 routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.9% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 679 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on six other city pairs in the data, including SFO to EWR (42), SFO to ORD (35) and SFO to AUS (23), but none flew often enough under UA 737 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SEA to SFO only.
One caution: this is a thin sample. 362 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 737
For a booking, UA 737 is a flight to put a long connection behind. 13.9% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- SEA to SFO, every carrier and departure
- SFO to SEA, the return direction
- Delta Air Lines 1412 on the same route66.3%
- Delta Air Lines 2635 on the same route75.1%
- SkyWest Airlines 3707 on the same route74.8%
- SkyWest Airlines 3991 on the same route69.3%
- Seattle-Tacoma International (SEA) delay statistics
- San Francisco International (SFO) 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
- The best time of day to fly, according to 7.04 million flight records
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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.