Flight number record

UA 2021

United Airlines · Washington to San Juan

Route: IAD → SJU
Departs: 08:27
Flights: 347
Period: July 2025 to June 2026

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

UA 2021 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. 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 9 points better than the US average of 77.6%. That gap is worth roughly 94 fewer late arrivals for every thousand flights.

On time

87.0%

Arrivals under 15 minutes late, of 345 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

0.58%

National rate is 1.81%

1 hour+ late

3.2%

National rate is 8.1%

These figures cover 347 flights between July 2025 and June 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.

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 (94 flights) and 08:39 (51 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 08:27153 flights44.1%
Departs 08:3494 flights27.1%
Departs 08:3951 flights14.7%

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 08:27 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 84.1%, and UA 2021 runs 3 points better at 87.0%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

UA 2021 next to IAD to SJU

Every carrier on IAD to SJU combined arrived on time 76.3% of the time across 698 flights, so UA 2021 is 11 points ahead of it. United flew 609 flights on the same city pair under all its flight numbers, including this one, and those ran 80.8% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 8 points.

UA 2021 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 2021thin sample	347	87.0%	50 min	0.58%	A+
All United Airlines on IAD–SJU	609	80.8%	51 min	0.49%	B+
All carriers on IAD–SJU	698	76.3%	93 min	0.72%	B+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	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 2025 at 78.7%, a swing of 15 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 202575 flights78.7%
Oct–Dec 202592 flights87.0%
Jan–Mar 202689 flights87.4%
Apr–Jun 202691 flights93.4%

Scale runs 70% 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 Sunday at 82.4%. Each day rests on about 50 flights, so a gap of 13 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 2021 runs late

One category carries most of the weight here. National Airspace System accounts for 57% of the 2,266 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
57%
Carrier
15%
Extreme weather
15%
Late-arriving aircraft
13%

Extreme weather accounts for 15% 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 2.4 times the usual weather exposure. The split is drawn from 2,266 delay minutes reported on UA 2021.

Cancellations are rare at 0.58%, below the national 1.81% 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 8.1% 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, UA 2021 has one of the better records a US domestic flight can show: 87.0% on time and 0.58% cancelled. That is a base rate, not a promise about any single 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures