Flight number record

UA 1635

United Airlines · Los Angeles to Washington

Route: LAX → IAD
Departs: 12:55
Flights: 347
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1635, check with United Airlines.

UA 1635 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 10 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 347 flights, with a median arrival 11 minutes early.

Set against the rest of the country, UA 1635's record is 10 points better than the US average of 77.6%. That gap is worth roughly 95 fewer late arrivals for every thousand flights.

On time

87.1%

Arrivals under 15 minutes late, of 342 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

0.58%

National rate is 1.81%

1 hour+ late

4.7%

National rate is 8.1%

These figures cover 347 flights between July 2025 and June 2026. The median arrival is 11 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 1635 flies

UA 1635 flies LAX to IAD without a single fixed slot. Its most common scheduled departure was 12:55, used on 63 of 347 flights, with 13:20 (56 flights) and 12:45 (51 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 12:5563 flights18.2%
Departs 13:2056 flights16.1%
Departs 12:4551 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 12:55 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and UA 1635 runs 8 points better at 87.1%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 1635 next to LAX to IAD

Every carrier on LAX to IAD combined arrived on time 86.7% of the time across 2,454 flights, so UA 1635 is about level with it. United flew 2,319 flights on the same city pair under all its flight numbers, including this one, and those ran 87.2% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 8 points.

UA 1635 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1635thin sample	347	87.1%	73 min	0.58%	A+
All United Airlines on LAX–IAD	2,319	87.2%	57 min	0.73%	A+
All carriers on LAX–IAD	2,454	86.7%	58 min	0.69%	A+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 1635 quarter by quarter

UA 1635 did not run the same all year. Its best quarter was Oct–Dec 2025 at 93.5% on time and its weakest Jul–Sep 2025 at 72.2%, a swing of 21 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 202592 flights72.2%
Oct–Dec 202592 flights93.5%
Jan–Mar 202672 flights91.4%
Apr–Jun 202691 flights92.2%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1635 ranged from 82.6% on Tuesday to 92.3% on Thursday. With about 50 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why UA 1635 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 3,230 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.

Late-arriving aircraft
43%
Carrier
33%
National Airspace System
24%

43% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 3,230 reported delay minutes here, that single category outweighs weather by 43 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 3,230 delay minutes reported on UA 1635.

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 4.7% 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 2,288 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.

The same number turns up on three other city pairs in the data, including IAD to ATL (82), IAD to ORF (28) and SEA to LAX (25), but none flew often enough under UA 1635 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to LAX to IAD only.

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 1635

For a booking, UA 1635 has one of the better records a US domestic flight can show: 87.1% 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