Flight profile · United Airlines
UA668
San Juan (SJU) to Houston (IAH) · scheduled 2:55 PM – 6:46 PM
How UA668 performs
1,127 operations, July 2023 – July 2026.
UA668 arrived on time 75.9% of the time, against 84.3% for all SJU → IAH flights, so this departure is 8.4 percentage points worse than the route as a whole. Against United Airlines’ own flights on this route it is 9.7 points worse.
Source: US DOT Bureau of Transportation Statistics · 1,127 operations, July 2023 – July 2026 · If UA668 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where UA668 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| UA668 | 75.9% | 0.98% | -1 min | 6.8% | 1,127 |
| United Airlines on SJU → IAH | 85.6% | 0.87% | -10 min | 4.4% | 2,543 |
| All SJU → IAH flights | 84.3% | 1.08% | -10 min | 4.9% | 2,877 |
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
Why UA668 runs late
Where US DOT attributed the delay minutes on this flight.
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for UA668 on SJU → IAH. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies UA668 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, UA668 pushed back an average of 47 minutes late; when it came in on time or early, an average of 2 minutes early.
Each departure is matched to the flight the same aircraft flew into SJU just before it, using the tail number in the DOT file, 1,106 of 1,120 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| UA668 | 22% | 76% | 5% |
| Network, same turn | 17% | 68% | 9% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often UA668’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often UA668 left 15 or more minutes late is higher than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
From pushback to gate
When it leaves SJU late, does that still matter by the time it reaches IAH?
UA668 pushes back an average of 10.1 minutes late and reaches the gate at IAH an average of 7.0 minutes late. The 3.1 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. Its 17.7 minutes on the taxiways at SJU is about what any departure from the airport in that hour spends.
On arrival at IAH, UA668 spends 13.5 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 2.9 minutes longer than a typical IAH arrival (10.7 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached IAH. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 8,889 departures from SJU scheduled in the clock hour UA668 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at IAH (359,471 flights), not just UA668’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
The hour it leaves SJU
Part of any flight’s record belongs to the clock rather than to the flight. UA668 has one departure time, so this is what that time is worth.
On-time arrival rate. 8,889 departures from SJU are scheduled in the 2 PM–3 PM hour over the period, against 109,598 across the whole day.
UA668 is scheduled out of SJU at 2:55 PM, in the 2 PM–3 PM bank. Departures from SJU in that hour arrive on time 74.4% of the time against 76.2% across the airport’s whole day, so the hour UA668 leaves in is an ordinary one for SJU and explains nothing about its record either way.
The two airport figures cover every departure from SJU to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Hours below 120 departures are not scored.
By day of week
Does UA668 run worse on particular days?
Tuesday is historically the most reliable day and Saturday the least, a gap of 8.9 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Days with fewer than 120 operations are not scored.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
41 min late
against a median of 1 min early
Percentiles over 1,127 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| UA1644 | United Airlines | 94.0% | 14 min early | 985 |
| UA668 this flight | United Airlines | 75.9% | 1 min early | 1,127 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. UA668 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 1,127 records of UA668 operating SJU → IAH, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed