Flight number record
UA 1663
United Airlines · Houston to Philadelphia
- Route
- IAH → PHL
- Departs
- 18:05
- Flights
- 285
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1663, check with United Airlines.
UA 1663 sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 285 flights, with a median arrival 3 minutes early.
Key figures
On time
75.2%
Arrivals under 15 minutes late, of 282 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
1.05%
National rate is 1.89%
1 hour+ late
11.0%
National rate is 8.3%
These figures cover 285 flights between September 2025 and August 2026. Beyond the headline rate, 11.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 91 of 285 flights, with 18:30 (52 flights) and 18:40 (40 flights) next.
- Departs 18:0591 flights31.9%
- Departs 18:3052 flights18.2%
- Departs 18:4040 flights14.0%
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 18:05 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and UA 1663 runs 7 points better at 75.2%. 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 1663 next to IAH to PHL
Every carrier on IAH to PHL combined arrived on time 78.8% of the time across 1,878 flights, so UA 1663 is 4 points behind it. United flew 954 flights on the same city pair under all its flight numbers, including this one, and those ran 81.5% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1663thin sample | 285 | 75.2% | 69 min | 1.05% | B |
| All United Airlines on IAH–PHL | 954 | 81.5% | 69 min | 0.94% | B+ |
| All carriers on IAH–PHL | 1,878 | 78.8% | 90 min | 1.86% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | 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 2026 at 48.0%, a swing of 41 points on roughly 71 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 202524 flights—
- Oct–Dec 202566 flights78.8%
- Jan–Mar 202666 flights88.9%
- Apr–Jun 202679 flights75.9%
- Jul–Sep 202650 flights48.0%
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1663 did best on Tuesday at 88.9% on time and worst on Thursday at 61.9%. Each day rests on about 41 flights, so a gap of 27 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1663 runs when it is late
The 70 late arrivals split 16 under half an hour, 23 between 30 and 60 minutes, and 31 an hour or more.
- 15+ min early62 flights22.0%
- Within 15 min150 flights53.2%
- 15–29 min late16 flights5.7%
- 30–59 min late23 flights8.2%
- 1–2 hours late20 flights7.1%
- 2+ hours late11 flights3.9%
Scale runs 0% to 100%.
Share of 282 completed flights by arrival against schedule.
9 of 70 late departures made up the time and arrived on time, 13% of them. 9 flights left on time and still arrived late.
The worst days
Worst days for UA 1663
The latest arrival of the period was on 2 June 2026, 3 hours 39 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 |
|---|---|---|
| 2 June 2026 | 3 hours 39 minutes | Late-arriving aircraft |
| 28 July 2026 | 3 hours 17 minutes | Late-arriving aircraft |
| 1 May 2026 | 2 hours 58 minutes | Late-arriving aircraft |
| 9 July 2026 | 2 hours 55 minutes | Late-arriving aircraft |
| 15 February 2026 | 2 hours 50 minutes | Late-arriving aircraft |
Delay causes
Why UA 1663 runs late
Late-arriving aircraft accounts for 50% of the 4,827 delay minutes carriers reported here, and the remaining four split what is left.
- 50%Late-arriving aircraft
- 29%National Airspace System
- 20%Carrier
- 1%Extreme weather
50% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,827 reported delay minutes here, that single category outweighs weather by 35 to one. The split is drawn from 4,827 delay minutes reported on UA 1663.
Cancellations sit at 1.05% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
11.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
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.
The same number turns up on four other city pairs in the data, including EWR to FLL (31), IAH to JAC (24) 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. 285 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 75.2% on time with 1.05% cancelled over 285 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.