Flight number record

UA 1535

United Airlines · Washington to Houston

Route: IAD → IAH
Departs: 12:50
Flights: 307
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1535, check with United Airlines.

UA 1535 lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 307 flights, with a median arrival 11 minutes early.

Set against the rest of the country, UA 1535's record is 5 points better than the US average of 77.6%. That gap is worth roughly 46 fewer late arrivals for every thousand flights.

On time

82.2%

Arrivals under 15 minutes late, of 303 completed flights

Avg delay

80 min

Across delayed arrivals only, not all flights

Cancelled

0.65%

National rate is 1.81%

1 hour+ late

6.9%

National rate is 8.1%

These figures cover 307 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 1535 flies

UA 1535 flies IAD to IAH without a single fixed slot. Its most common scheduled departure was 12:50, used on 184 of 307 flights, with 12:55 (68 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 12:50184 flights59.9%
Departs 12:5568 flights22.1%

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 12:50 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and UA 1535 runs 3 points better at 82.2%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 1535 next to IAD to IAH

Every carrier on IAD to IAH combined arrived on time 83.7% of the time across 1,869 flights, so UA 1535 is 2 points behind it. Across its whole network United Airlines managed 79.0%, which this flight beats by 3 points.

UA 1535 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1535thin sample	307	82.2%	80 min	0.65%	B+
All United Airlines on IAD–IAH	1,869	83.7%	68 min	0.48%	B+
All carriers on IAD–IAH	1,869	83.7%	68 min	0.48%	B+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 1535 quarter by quarter

UA 1535 did not run the same all year. Its best quarter was Jan–Mar 2026 at 91.0% on time and its weakest Jul–Sep 2025 at 67.3%, a swing of 24 points on roughly 77 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 202555 flights67.3%
Oct–Dec 202592 flights80.4%
Jan–Mar 202669 flights91.0%
Apr–Jun 202691 flights86.5%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1535 did best on Tuesday at 90.7% on time and worst on Thursday at 70.5%. Each day rests on about 44 flights, so a gap of 20 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 1535 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 4,308 reported delay minutes.

Late-arriving aircraft
40%
National Airspace System
32%
Carrier
22%
Extreme weather
6%

40% 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 4,308 reported delay minutes here, that single category outweighs weather by 7 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 4,308 delay minutes reported on UA 1535.

Cancellations are rare at 0.65%, 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

6.9% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.

The 1,190 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The same number turns up on five other city pairs in the data, including IAH to DFW (157), RDU to IAD (118) and IAH to MSY (34), but none flew often enough under UA 1535 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAD to IAH only.

One caution: this is a thin sample. 307 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 1535

For a booking, read UA 1535 as 82.2% on time with 0.65% cancelled over 307 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures