Flight number record
UA 660
United Airlines · Chicago to San Diego
- Route
- ORD → SAN
- Departs
- 08:46
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 660, check with United Airlines.
UA 660 lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 365 flights, with a median arrival 11 minutes early.
Set against the rest of the country, UA 660's record is 5 points better than the US average of 77.3%. That gap is worth roughly 49 fewer late arrivals for every thousand flights.
Key figures
On time
82.2%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
65 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
6.0%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 11 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Schedule
When UA 660 flies
UA 660 flies ORD to SAN without a single fixed slot. Its most common scheduled departure was 08:46, used on 156 of 365 flights, with 09:13 (55 flights) and 08:47 (45 flights) next.
- Departs 08:46156 flights42.7%
- Departs 09:1355 flights15.1%
- Departs 08:4745 flights12.3%
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 08:46 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and UA 660 runs level with that at 82.2%. 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 660 next to ORD to SAN
Every carrier on ORD to SAN combined arrived on time 70.5% of the time across 3,945 flights, so UA 660 is 12 points ahead of it. United flew 1,677 flights on the same city pair under all its flight numbers, including this one, and those ran 76.4% 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 660 | 365 | 82.2% | 65 min | 0.00% | B+ |
| All United Airlines on ORD–SAN | 1,677 | 76.4% | 62 min | 0.42% | B+ |
| All carriers on ORD–SAN | 3,945 | 70.5% | 66 min | 1.29% | C |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 660 quarter by quarter
UA 660 did not run the same all year. Its best quarter was Jan–Mar 2026 at 87.8% on time and its weakest Oct–Dec 2025 at 75.0%, a swing of 13 points on roughly 73 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 202530 flights86.7%
- Oct–Dec 202592 flights75.0%
- Jan–Mar 202690 flights87.8%
- Apr–Jun 202691 flights85.7%
- Jul–Sep 202662 flights77.4%
Scale runs 65% to 95%.
By weekday, UA 660 did best on Tuesday at 90.4% on time and worst on Sunday at 75.0%. Each day rests on about 52 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 660 runs when it is late
UA 660 often beats the schedule: 152 of 365 completed flights, 42%, arrived 15 minutes or more early. The 65 late arrivals split 25 under half an hour, 18 between 30 and 60 minutes, and 22 an hour or more.
- 15+ min early152 flights41.6%
- Within 15 min148 flights40.5%
- 15–29 min late25 flights6.8%
- 30–59 min late18 flights4.9%
- 1–2 hours late10 flights2.7%
- 2+ hours late12 flights3.3%
Scale runs 0% to 100%.
Share of 365 completed flights by arrival against schedule.
8 of 52 late departures made up the time and arrived on time, 15% of them. In the other direction, 21 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SAN.
The worst days
Worst days for UA 660
The latest arrival of the period was on 17 October 2025, 5 hours 4 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across October, March, January and December, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 17 October 2025 | 5 hours 4 minutes | Carrier |
| 6 March 2026 | 3 hours 44 minutes | Extreme weather |
| 25 January 2026 | 3 hours 36 minutes | Late-arriving aircraft |
| 7 December 2025 | 3 hours 18 minutes | Carrier |
| 19 December 2025 | 3 hours 15 minutes | Late-arriving aircraft |
Delay causes
Why UA 660 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 4,234 reported delay minutes.
- 40%Carrier
- 28%National Airspace System
- 24%Late-arriving aircraft
- 8%Extreme weather
The largest share of delay minutes, 40%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,711 of the 4,234 delay minutes reported here. The split is drawn from 4,234 delay minutes reported on UA 660.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
6.0% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 1,723 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 PHL to ORD (160), BWI to ORD (18) and SAV to ORD (1), but none flew often enough under UA 660 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ORD to SAN only.
One caution: this is a thin sample. 365 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 660
For a booking, read UA 660 as 82.2% on time with 0.00% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- ORD to SAN, every carrier and departure
- SAN to ORD, the return direction
- United Airlines 2683 on the same route78.7%
- Alaska Airlines 1470 on the same route76.1%
- Alaska Airlines 1447 on the same route68.4%
- Chicago O'Hare International (ORD) delay statistics
- San Diego International (SAN) 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
- Worst months to fly in the US, ranked by the data
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.