Flight number record

UA 660

United Airlines · Chicago to San Diego

Route: ORD → SAN
Departs: 08:46
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 660, check with United Airlines.

UA 660 lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 365 flights, with a median arrival 9 minutes early.

Set against the rest of the country, UA 660's record is 6 points better than the US average of 77.6%. That gap is worth roughly 60 fewer late arrivals for every thousand flights.

On time

83.6%

Arrivals under 15 minutes late, of 365 completed flights

Avg delay

63 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

1 hour+ late

5.5%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 9 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.

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 94 of 365 flights, with 09:05 (86 flights) and 09:13 (68 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:4694 flights25.8%
Departs 09:0586 flights23.6%
Departs 09:1368 flights18.6%

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 08:46 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 660 runs level with that at 83.6%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

UA 660 next to ORD to SAN

Every carrier on ORD to SAN combined arrived on time 71.2% of the time across 3,807 flights, so UA 660 is 12 points ahead of it. United flew 1,672 flights on the same city pair under all its flight numbers, including this one, and those ran 77.0% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 5 points.

UA 660 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 660	365	83.6%	63 min	0.00%	B+
All United Airlines on ORD–SAN	1,672	77.0%	64 min	0.30%	B+
All carriers on ORD–SAN	3,807	71.2%	67 min	1.18%	C
United Airlines, whole network	821,041	79.0%	72 min	1.01%	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 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 flights85.9%
Oct–Dec 202592 flights75.0%
Jan–Mar 202690 flights87.8%
Apr–Jun 202691 flights85.7%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, UA 660 did best on Tuesday at 92.5% on time and worst on Sunday at 76.9%. Each day rests on about 52 flights, so a gap of 16 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 660 runs late

One category carries most of the weight here. Carrier accounts for 45% of the 3,775 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.

Carrier
45%
National Airspace System
25%
Late-arriving aircraft
20%
Extreme weather
9%

The largest share of delay minutes, 45%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,711 of the 3,775 delay minutes reported here. The split is drawn from 3,775 delay minutes reported on UA 660.

Cancellations are rare at 0.00%, below the national 1.81% 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

5.5% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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 four other city pairs in the data, including PHL to ORD (119), RDU to ORD (21) and BWI to ORD (18), 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 83.6% on time with 0.00% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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.

Key figures