Flight number record
UA 1543
United Airlines · Newark to San Juan
- Route
- EWR → SJU
- Departs
- 19:37
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 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 77.3%, so UA 1543 runs 13 points behind the country as a whole. Across a thousand flights that is about 131 extra late arrivals.
Key figures
On time
64.2%
Arrivals under 15 minutes late, of 358 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
1.65%
National rate is 1.89%
1 hour+ late
13.4%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. Beyond the headline rate, 13.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 (135 flights) and 19:54 (55 flights) next.
- Departs 19:37153 flights42.0%
- Departs 19:45135 flights37.1%
- Departs 19:5455 flights15.1%
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 19:37 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, 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.
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Against the route
UA 1543 next to EWR to SJU
Every carrier on EWR to SJU combined arrived on time 69.9% of the time across 2,078 flights, so UA 1543 is 6 points behind it. United flew 1,113 flights on the same city pair under all its flight numbers, including this one, and those ran 69.7% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 15 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1543thin sample | 364 | 64.2% | 73 min | 1.65% | D |
| All United Airlines on EWR–SJU | 1,113 | 69.7% | 80 min | 2.16% | C |
| All carriers on EWR–SJU | 2,078 | 69.9% | 81 min | 3.03% | C− |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | 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 73 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 202530 flights70.0%
- Oct–Dec 202591 flights53.3%
- Jan–Mar 202690 flights58.6%
- Apr–Jun 202691 flights81.3%
- Jul–Sep 202662 flights60.0%
Scale runs 45% to 85%.
By weekday, UA 1543 did best on Tuesday at 76.5% on time and worst on Monday at 55.8%. Each day rests on about 52 flights, so a gap of 21 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1543 runs when it is late
The 128 late arrivals split 42 under half an hour, 38 between 30 and 60 minutes, and 48 an hour or more.
- 15+ min early78 flights21.8%
- Within 15 min152 flights42.5%
- 15–29 min late42 flights11.7%
- 30–59 min late38 flights10.6%
- 1–2 hours late26 flights7.3%
- 2+ hours late22 flights6.1%
Scale runs 0% to 100%.
Share of 358 completed flights by arrival against schedule.
34 of 133 late departures made up the time and arrived on time, 26% of them. In the other direction, 29 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SJU.
The worst days
Worst days for UA 1543
The latest arrival of the period was on 17 November 2025, 11 hours 20 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 17 November 2025 | 11 hours 20 minutes | Carrier |
| 5 July 2026 | 5 hours 51 minutes | Extreme weather |
| 8 February 2026 | 4 hours 56 minutes | Carrier |
| 28 July 2026 | 4 hours 55 minutes | Late-arriving aircraft |
| 2 August 2026 | 4 hours 15 minutes | Carrier |
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 9,314 reported delay minutes.
- 36%Late-arriving aircraft
- 34%Carrier
- 26%National Airspace System
- 4%Extreme weather
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,314 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 9,314 delay minutes reported on UA 1543.
Cancellations sit at 1.65% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
13.4% 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.
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. 13.4% 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 1556 on the same route76.9%
- United Airlines 2143 on the same route67.1%
- 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
- 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.