Flight profile · United Airlines
UA1556
Newark (EWR) to San Juan (SJU) · scheduled 9:46 AM – 1:45 PM
How UA1556 performs
1,127 operations, July 2023 – July 2026.
UA1556 arrived on time 77.2% of the time, against 70.0% for all EWR → SJU flights, so this departure is 7.2 percentage points better than the route as a whole. Against United Airlines’ own flights on this route it is 5.6 points better.
Source: US DOT Bureau of Transportation Statistics · 1,127 operations, July 2023 – July 2026 · If UA1556 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where UA1556 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 |
|---|---|---|---|---|---|
| UA1556 | 77.2% | 0.71% | -5 min | 5.6% | 1,127 |
| United Airlines on EWR → SJU | 71.6% | 1.41% | -3 min | 10.5% | 3,397 |
| All EWR → SJU flights | 70.0% | 1.96% | -3 min | 12.0% | 6,837 |
UA1556 has cancelled 0.71% of its scheduled departures (8 of 1,127), against 1.96% for all EWR → SJU flights — this specific departure cancels 1.3 percentage points less often than the route as a whole. Different flight numbers on the same route can carry different aircraft, crews and schedules, so this is a fact about UA1556 specifically, not about the route it flies.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
Why UA1556 runs late
Where US DOT attributed the delay minutes on this flight.
airspace and airport capacity, including weather-driven flow control
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for UA1556 on EWR → SJU. 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 UA1556 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, UA1556 pushed back an average of 16 minutes late; when it came in on time or early, an average of 2 minutes late.
Each departure is matched to the flight the same aircraft flew into EWR just before it, using the tail number in the DOT file, 908 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 |
|---|---|---|---|
| UA1556 | 14% | 34% | 10% |
| 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 UA1556’s aircraft landed 15 or more minutes late is lower than the network’s and, once the aircraft was late, how often UA1556 left 15 or more minutes late is lower 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 EWR late, does that still matter by the time it reaches SJU?
UA1556 pushes back an average of 7.0 minutes late and reaches the gate at SJU an average of 4.8 minutes late. The 2.2 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 26.3 minutes on the taxiways at EWR is about what any departure from the airport in that hour spends.
On arrival at SJU, UA1556 spends 6.4 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 about what any arrival at SJU spends on the ground before reaching the gate.
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 SJU. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 25,521 departures from EWR scheduled in the clock hour UA1556 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at SJU (109,607 flights), not just UA1556’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026
The hour it leaves EWR
Part of any flight’s record belongs to the clock rather than to the flight. UA1556 has one departure time, so this is what that time is worth.
On-time arrival rate. 25,521 departures from EWR are scheduled in the 9 AM–10 AM hour over the period, against 387,621 across the whole day.
UA1556 is scheduled out of EWR at 9:46 AM, in the 9 AM–10 AM bank. Departures from EWR in that hour arrive on time 83.2% of the time against 77.7% across the airport’s whole day — the slot alone is worth 5.5 points better before anything about this particular flight is considered.
The two airport figures cover every departure from EWR 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 UA1556 run worse on particular days?
Sunday is historically the most reliable day and Saturday the least, a gap of 15.4 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.
39 min late
against a median of 5 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 |
|---|---|---|---|---|
| UA1556 this flight | United Airlines | 77.2% | 5 min early | 1,127 |
| UA2143 | United Airlines | 74.7% | 7 min early | 1,127 |
| UA1543 | United Airlines | 62.5% | 3 min late | 1,124 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. UA1556 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 UA1556 operating EWR → SJU, 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
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