Flight number record
UA 1563
United Airlines · Houston to Ontario
- Route
- IAH → ONT
- Departs
- 20:31
- Flights
- 325
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1563, check with United Airlines.
UA 1563 lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 325 flights, with a median arrival 8 minutes early.
Key figures
On time
79.6%
Arrivals under 15 minutes late, of 324 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
8.0%
National rate is 8.3%
These figures cover 325 flights between September 2025 and August 2026. Beyond the headline rate, 8.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 1563 flies
UA 1563 flies IAH to ONT without a single fixed slot. Its most common scheduled departure was 20:31, used on 82 of 325 flights, with 20:15 (73 flights) next.
- Departs 20:3182 flights25.2%
- Departs 20:1573 flights22.5%
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 20:31 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and UA 1563 runs 10 points better at 79.6%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
UA 1563 next to IAH to ONT
Every carrier on IAH to ONT combined arrived on time 80.9% of the time across 574 flights, so UA 1563 is about level with it. Across its whole network United Airlines managed 78.8%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1563thin sample | 325 | 79.6% | 61 min | 0.00% | B+ |
| All United Airlines on IAH–ONTthin sample | 356 | 80.3% | 62 min | 0.00% | B+ |
| All carriers on IAH–ONT | 574 | 80.9% | 60 min | 0.17% | B+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1563 quarter by quarter
UA 1563 did not run the same all year. Its best quarter was Jan–Mar 2026 at 87.4% on time and its weakest Oct–Dec 2025 at 70.0%, a swing of 17 points on roughly 81 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 20256 flights—
- Oct–Dec 202591 flights70.0%
- Jan–Mar 202687 flights87.4%
- Apr–Jun 202691 flights81.3%
- Jul–Sep 202650 flights80.0%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1563 ranged from 76.1% on Saturday to 84.4% on Wednesday. With about 46 flights behind each day, a spread of 8 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 1563 runs when it is late
UA 1563 often beats the schedule: 104 of 324 completed flights, 32%, arrived 15 minutes or more early. The 66 late arrivals split 21 under half an hour, 19 between 30 and 60 minutes, and 26 an hour or more.
- 15+ min early104 flights32.1%
- Within 15 min154 flights47.5%
- 15–29 min late21 flights6.5%
- 30–59 min late19 flights5.9%
- 1–2 hours late19 flights5.9%
- 2+ hours late7 flights2.2%
Scale runs 0% to 100%.
Share of 324 completed flights by arrival against schedule.
A late pushback is often recovered here: of 88 departures that left 15 minutes late or more, 30 still arrived on time. 8 flights left on time and still arrived late.
The worst days
Worst days for UA 1563
The latest arrival of the period was on 16 March 2026, 4 hours 38 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 16 March 2026 | 4 hours 38 minutes | Late-arriving aircraft |
| 24 November 2025 | 3 hours 20 minutes | Late-arriving aircraft |
| 29 November 2025 | 3 hours 18 minutes | Late-arriving aircraft |
| 16 October 2025 | 2 hours 42 minutes | Late-arriving aircraft |
| 1 May 2026 | 2 hours 38 minutes | Late-arriving aircraft |
Delay causes
Why UA 1563 runs late
Late-arriving aircraft accounts for 52% of the 4,021 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Late-arriving aircraft
- 37%Carrier
- 7%National Airspace System
- 3%Extreme weather
52% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,021 reported delay minutes here, that single category outweighs weather by 15 to one. The split is drawn from 4,021 delay minutes reported on UA 1563.
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
8.0% 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.
The 1,334 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.
The same number turns up on five other city pairs in the data, including PIT to IAH (78), TPA to IAH (32) and JAX to IAH (21), but none flew often enough under UA 1563 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAH to ONT only.
One caution: this is a thin sample. 325 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 1563
For a booking, read UA 1563 as 79.6% on time with 0.00% cancelled over 325 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- George Bush Intercontinental (IAH) delay statistics
- Ontario International (ONT) 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.