Flight number record
UA 2179
United Airlines · Chicago to San Francisco
- Route
- ORD → SFO
- Departs
- 18:20
- Flights
- 339
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 2179, check with United Airlines.
UA 2179 earns an F, which is as low as this site's scale goes for a reason. Only 46.9% of flights arrive inside the 15-minute window, 31 points worse than the national rate of 77.6%. Late arrivals average about an hour. Treat any tight connection here as a coin flip. That rests on 339 flights, with a median arrival 16 minutes late.
The national on-time rate over the same period is 77.6%, so UA 2179 runs 31 points behind the country as a whole. Across a thousand flights that is about 307 extra late arrivals.
Key figures
On time
46.9%
Arrivals under 15 minutes late, of 335 completed flights
Avg delay
63 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.81%
1 hour+ late
18.5%
National rate is 8.1%
These figures cover 339 flights between July 2025 and June 2026. Beyond the headline rate, 18.5% 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 2179 flies
UA 2179 flies ORD to SFO without a single fixed slot. Its most common scheduled departure was 18:20, used on 167 of 339 flights, with 18:25 (55 flights) and 18:35 (50 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 18:20167 flights49.3%
- Departs 18:2555 flights16.2%
- Departs 18:3550 flights14.7%
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 18:20 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and UA 2179 runs 21 points worse at 46.9%. 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 2179 next to ORD to SFO
Every carrier on ORD to SFO combined arrived on time 67.6% of the time across 5,627 flights, so UA 2179 is 21 points behind it. United flew 3,813 flights on the same city pair under all its flight numbers, including this one, and those ran 69.8% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 32 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2179thin sample | 339 | 46.9% | 63 min | 1.18% | F |
| All United Airlines on ORD–SFO | 3,813 | 69.8% | 73 min | 1.05% | C |
| All carriers on ORD–SFO | 5,627 | 67.6% | 73 min | 1.32% | C |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 2179 quarter by quarter
UA 2179 did not run the same all year. Its best quarter was Jan–Mar 2026 at 55.1% on time and its weakest Apr–Jun 2026 at 36.7%, a swing of 18 points on roughly 85 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 flights53.8%
- Oct–Dec 202566 flights40.0%
- Jan–Mar 202690 flights55.1%
- Apr–Jun 202691 flights36.7%
Scale runs 30% to 60%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2179 did best on Tuesday at 60.0% on time and worst on Wednesday at 37.5%. Each day rests on about 48 flights, so a gap of 23 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 2179 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 11,000 reported delay minutes.
- 40%National Airspace System
- 33%Late-arriving aircraft
- 17%Carrier
- 10%Extreme weather
40% 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 4,433 minutes out of 11,000, against a national NAS share of 21%. The split is drawn from 11,206 delay minutes reported on UA 2179.
Cancellations sit at 1.18% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
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. 18.5% 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.
At 1,846 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.
UA 2179 is not only a ORD to SFO flight. It also flew SFO to LAX (279 flights, 72.7% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.
One caution: this is a thin sample. 339 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SFO to LAXthin sample | 279 | 72.7% | 51 min | 0.36% | C+ |
What to do with this
Booking UA 2179
For a booking, UA 2179 is a flight to put a long connection behind. 18.5% 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
- ORD to SFO, every carrier and departure
- SFO to ORD, the return direction
- United Airlines 1577 on the same route73.4%
- American Airlines 1253 on the same route71.2%
- Chicago O'Hare International (ORD) 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
- 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.