Flight number record
UA 664
United Airlines · Las Vegas to Chicago
- Route
- LAS → ORD
- Departs
- 07:00
- Flights
- 352
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 664, check with United Airlines.
UA 664 earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 352 flights, with a median arrival 12 minutes early.
Set against the rest of the country, UA 664's record is 9 points better than the US average of 77.3%. That gap is worth roughly 89 fewer late arrivals for every thousand flights.
Key figures
On time
86.2%
Arrivals under 15 minutes late, of 348 completed flights
Avg delay
93 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
1 hour+ late
3.7%
National rate is 8.3%
These figures cover 352 flights between September 2025 and August 2026. The median arrival is 12 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 664 flies
UA 664 flies LAS to ORD without a single fixed slot. Its most common scheduled departure was 07:00, used on 223 of 352 flights, with 07:15 (94 flights) next.
- Departs 07:00223 flights63.4%
- Departs 07:1594 flights26.7%
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 07:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and UA 664 runs 3 points worse at 86.2%. 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 664 next to LAS to ORD
Every carrier on LAS to ORD combined arrived on time 75.6% of the time across 5,148 flights, so UA 664 is 11 points ahead of it. United flew 2,354 flights on the same city pair under all its flight numbers, including this one, and those ran 78.2% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 664thin sample | 352 | 86.2% | 93 min | 0.28% | A+ |
| All United Airlines on LAS–ORD | 2,354 | 78.2% | 76 min | 0.34% | B+ |
| All carriers on LAS–ORD | 5,148 | 75.6% | 88 min | 1.24% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 664 quarter by quarter
UA 664 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Jul–Sep 2026 at 75.0%, a swing of 22 points on roughly 70 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 flights96.7%
- Oct–Dec 202590 flights90.0%
- Jan–Mar 202688 flights89.5%
- Apr–Jun 202682 flights82.9%
- Jul–Sep 202662 flights75.0%
Scale runs 65% to 100%.
By weekday, UA 664 did best on Monday at 92.3% on time and worst on Friday at 77.6%. Each day rests on about 50 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 664 runs when it is late
UA 664 often beats the schedule: 155 of 348 completed flights, 45%, arrived 15 minutes or more early. The 48 late arrivals split 21 under half an hour, 14 between 30 and 60 minutes, and 13 an hour or more.
- 15+ min early155 flights44.5%
- Within 15 min145 flights41.7%
- 15–29 min late21 flights6.0%
- 30–59 min late14 flights4.0%
- 1–2 hours late1 flights0.3%
- 2+ hours late12 flights3.4%
Scale runs 0% to 100%.
Share of 348 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 27 departures that left 15 minutes late or more, only 1 made it up before arrival. In the other direction, 22 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 ORD.
The worst days
Worst days for UA 664
The latest arrival of the period was on 29 November 2025, 9 hours 16 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On four of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 29 November 2025 | 9 hours 16 minutes | National Airspace System |
| 25 May 2026 | 8 hours 1 minute | Carrier |
| 14 November 2025 | 7 hours 28 minutes | Carrier |
| 20 June 2026 | 7 hours 9 minutes | Carrier |
| 4 March 2026 | 4 hours 20 minutes | Carrier |
Delay causes
Why UA 664 runs late
Carrier accounts for 46% of the 4,460 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Carrier
- 45%National Airspace System
- 9%Late-arriving aircraft
The largest share of delay minutes, 46%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,051 of the 4,460 delay minutes reported here. The split is drawn from 4,460 delay minutes reported on UA 664.
Cancellations are rare at 0.28%, 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 routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.7% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 1,514 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 seven other city pairs in the data, including ORD to MCI (136), ORD to SRQ (56) and ORD to LGA (35), but none flew often enough under UA 664 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to LAS to ORD only.
One caution: this is a thin sample. 352 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 664
For a booking, UA 664 has one of the better records a US domestic flight can show: 86.2% on time and 0.28% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- LAS to ORD, every carrier and departure
- ORD to LAS, the return direction
- United Airlines 2102 on the same route90.7%
- American Airlines 2258 on the same route88.1%
- United Airlines 1583 on the same route80.1%
- United Airlines 706 on the same route65.0%
- Harry Reid International (LAS) delay statistics
- Chicago O'Hare International (ORD) 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.