Flight number record
UA 1663
United Airlines · Houston to Philadelphia
- Route
- IAH → PHL
- Departs
- 18:05
- Flights
- 264
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1663, check with United Airlines.
UA 1663 lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 264 flights, with a median arrival 4 minutes early.
Key figures
On time
79.7%
Arrivals under 15 minutes late, of 261 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.14%
National rate is 1.81%
1 hour+ late
8.4%
National rate is 8.1%
These figures cover 264 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% 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 1663 flies
UA 1663 flies IAH to PHL without a single fixed slot. Its most common scheduled departure was 18:05, used on 72 of 264 flights, with 18:30 (52 flights) and 18:40 (40 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 18:0572 flights27.3%
- Departs 18:3052 flights19.7%
- Departs 18:4040 flights15.2%
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 18:05 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and UA 1663 runs 12 points better at 79.7%. 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 1663 next to IAH to PHL
Every carrier on IAH to PHL combined arrived on time 79.7% of the time across 1,832 flights, so UA 1663 is about level with it. United flew 891 flights on the same city pair under all its flight numbers, including this one, and those ran 83.0% on time. Across its whole network United Airlines managed 79.0%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1663thin sample | 264 | 79.7% | 72 min | 1.14% | B |
| All United Airlines on IAH–PHL | 891 | 83.0% | 67 min | 1.01% | B |
| All carriers on IAH–PHL | 1,832 | 79.7% | 117 min | 2.07% | B |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 1663 quarter by quarter
UA 1663 did not run the same all year. Its best quarter was Jan–Mar 2026 at 88.9% on time and its weakest Jul–Sep 2025 at 75.5%, a swing of 13 points on roughly 66 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 202553 flights75.5%
- Oct–Dec 202566 flights78.8%
- Jan–Mar 202666 flights88.9%
- Apr–Jun 202679 flights75.9%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1663 did best on Tuesday at 97.4% on time and worst on Sunday at 66.7%. Each day rests on about 38 flights, so a gap of 31 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 1663 runs late
One category carries most of the weight here. Late-arriving aircraft accounts for 58% of the 3,791 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.
- 58%Late-arriving aircraft
- 24%Carrier
- 16%National Airspace System
- 1%Extreme weather
58% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 3,791 reported delay minutes here, that single category outweighs weather by 41 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 3,791 delay minutes reported on UA 1663.
Cancellations sit at 1.14% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
8.4% 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 a little over an hour, which a normal layover absorbs.
The 1,325 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on six other city pairs in the data, including EWR to FLL (31), IAD to ATL (31) and IAH to STL (24), but none flew often enough under UA 1663 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAH to PHL only.
One caution: this is a thin sample. 264 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 1663
For a booking, read UA 1663 as 79.7% on time with 1.14% cancelled over 264 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- IAH to PHL, every carrier and departure
- PHL to IAH, the return direction
- George Bush Intercontinental (IAH) delay statistics
- Philadelphia International (PHL) 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.