Flight number record

UA 2021

United Airlines · Washington to San Juan

Route: IAD → SJU
Departs: 08:27
Flights: 347
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s UA 2021, check with United Airlines.

UA 2021 earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 50 minutes. That rests on 347 flights, with a median arrival 7 minutes early.

Set against the rest of the country, UA 2021's record is 8 points better than the US average of 77.3%. That gap is worth roughly 76 fewer late arrivals for every thousand flights.

On time

84.9%

Arrivals under 15 minutes late, of 345 completed flights

Avg delay

51 min

Across delayed arrivals only, not all flights

Cancelled

0.58%

National rate is 1.89%

1 hour+ late

3.2%

National rate is 8.3%

These figures cover 347 flights between September 2025 and August 2026. The median arrival is 7 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

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Schedule

When UA 2021 flies

UA 2021 flies IAD to SJU without a single fixed slot. Its most common scheduled departure was 08:27, used on 153 of 347 flights, with 08:34 (135 flights) and 08:39 (38 flights) next.

Departs 08:27153 flights44.1%
Departs 08:34135 flights38.9%
Departs 08:3938 flights11.0%

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 08:27 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and UA 2021 runs level with that at 84.9%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

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Against the route

UA 2021 next to IAD to SJU

Every carrier on IAD to SJU combined arrived on time 75.9% of the time across 698 flights, so UA 2021 is 9 points ahead of it. United flew 636 flights on the same city pair under all its flight numbers, including this one, and those ran 78.3% on time. Across its whole network United Airlines managed 78.8%, which this flight beats by 6 points.

UA 2021 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 2021thin sample	347	84.9%	51 min	0.58%	B+
All United Airlines on IAD–SJU	636	78.3%	54 min	0.47%	B+
All carriers on IAD–SJU	698	75.9%	77 min	0.57%	B+
United Airlines, whole network	830,825	78.8%	73 min	1.02%	B

Across the year

UA 2021 quarter by quarter

UA 2021 did not run the same all year. Its best quarter was Apr–Jun 2026 at 93.4% on time and its weakest Jul–Sep 2026 at 67.7%, a swing of 26 points on roughly 87 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 202513 flights—
Oct–Dec 202592 flights87.0%
Jan–Mar 202689 flights87.4%
Apr–Jun 202691 flights93.4%
Jul–Sep 202662 flights67.7%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, UA 2021 did best on Wednesday at 95.7% on time and worst on Monday at 78.0%. Each day rests on about 50 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late UA 2021 runs when it is late

UA 2021 often beats the schedule: 113 of 345 completed flights, 33%, arrived 15 minutes or more early. The 52 late arrivals split 22 under half an hour, 19 between 30 and 60 minutes, and 11 an hour or more.

15+ min early113 flights32.8%
Within 15 min180 flights52.2%
15–29 min late22 flights6.4%
30–59 min late19 flights5.5%
1–2 hours late7 flights2.0%
2+ hours late4 flights1.2%

Scale runs 0% to 100%.

Share of 345 completed flights by arrival against schedule.

A late pushback is often recovered here: of 28 departures that left 15 minutes late or more, 9 still arrived on time. In the other direction, 33 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 2021

The latest arrival of the period was on 30 November 2025, 3 hours 50 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across November, January, July and December, with no single month standing out.

The latest arrivals of UA 2021 in the period
Date	Arrived late by	Largest filed cause
30 November 2025	3 hours 50 minutes	Late-arriving aircraft
27 January 2026	3 hours 39 minutes	Extreme weather
17 July 2026	2 hours 59 minutes	Late-arriving aircraft
5 December 2025	2 hours 4 minutes	Extreme weather
22 July 2026	1 hour 39 minutes	National Airspace System

Delay causes

Why UA 2021 runs late

National Airspace System accounts for 58% of the 2,640 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
58%
Late-arriving aircraft
16%
Carrier
14%
Extreme weather
13%

Extreme weather accounts for 13% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.1 times the usual weather exposure. The split is drawn from 2,640 delay minutes reported on UA 2021.

Cancellations are rare at 0.58%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 3.2% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

At 1,572 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 347 flights under UA 2021 in the data flew IAD 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. 347 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 2021

For a booking, read UA 2021 as 84.9% on time with 0.58% cancelled over 347 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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 22 October 2026; recomputed monthly. How this data is collected.

Key figures