Flight number record
UA 1543
United Airlines · Newark to San Juan
- Route
- EWR → SJU
- Departs
- 19:37
- Flights
- 364
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1543, check with United Airlines.
UA 1543 draws a D. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 364 flights, with a median arrival 2 minutes late.
The national on-time rate over the same period is 77.6%, so UA 1543 runs 13 points behind the country as a whole. Across a thousand flights that is about 134 extra late arrivals.
Key figures
On time
64.2%
Arrivals under 15 minutes late, of 358 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
1.65%
National rate is 1.81%
1 hour+ late
12.6%
National rate is 8.1%
These figures cover 364 flights between July 2025 and June 2026. Beyond the headline rate, 12.6% 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 1543 flies
UA 1543 flies EWR to SJU without a single fixed slot. Its most common scheduled departure was 19:37, used on 153 of 364 flights, with 19:45 (94 flights) and 19:54 (68 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 19:37153 flights42.0%
- Departs 19:4594 flights25.8%
- Departs 19:5468 flights18.7%
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 19:37 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and UA 1543 runs 4 points worse at 64.2%. 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 1543 next to EWR to SJU
Every carrier on EWR to SJU combined arrived on time 70.7% of the time across 2,101 flights, so UA 1543 is 7 points behind it. United flew 1,113 flights on the same city pair under all its flight numbers, including this one, and those ran 71.0% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 15 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1543thin sample | 364 | 64.2% | 72 min | 1.65% | D |
| All United Airlines on EWR–SJU | 1,113 | 71.0% | 75 min | 2.34% | C |
| All carriers on EWR–SJU | 2,101 | 70.7% | 82 min | 2.95% | C |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 1543 quarter by quarter
UA 1543 did not run the same all year. Its best quarter was Apr–Jun 2026 at 81.3% on time and its weakest Oct–Dec 2025 at 53.3%, a swing of 28 points on roughly 91 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 202592 flights63.3%
- Oct–Dec 202591 flights53.3%
- Jan–Mar 202690 flights58.6%
- Apr–Jun 202691 flights81.3%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, UA 1543 did best on Tuesday at 73.6% on time and worst on Monday at 60.0%. Each day rests on about 52 flights, so a gap of 14 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 1543 runs late
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 9,195 reported delay minutes.
- 41%Carrier
- 32%Late-arriving aircraft
- 25%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 3,746 of the 9,195 delay minutes reported here. The split is drawn from 9,195 delay minutes reported on UA 1543.
Cancellations sit at 1.65% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.6% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 1,608 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
Every one of the 364 flights under UA 1543 in the data flew EWR to SJU. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 364 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 1543
For a booking, UA 1543 is a flight to put a long connection behind. 12.6% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- EWR to SJU, every carrier and departure
- SJU to EWR, the return direction
- United Airlines 2143 on the same route70.0%
- United Airlines 1556 on the same route78.1%
- Newark Liberty International (EWR) delay statistics
- Luis Munoz Marin International (SJU) 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
- How often a connection fails at the major US hubs
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.