Flight number record

UA 1821

United Airlines · Houston to Raleigh

Route: IAH → RDU
Departs: 12:00
Flights: 268
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1821, check with United Airlines.

UA 1821 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 16 points better than the national rate of 77.6%. When something does go wrong the average delay runs roughly 55 minutes. That rests on 268 flights, with a median arrival 10 minutes early.

Set against the rest of the country, UA 1821's record is 16 points better than the US average of 77.6%. That gap is worth roughly 160 fewer late arrivals for every thousand flights.

On time

93.6%

Arrivals under 15 minutes late, of 265 completed flights

Avg delay

54 min

Across delayed arrivals only, not all flights

Cancelled

1.12%

National rate is 1.81%

1 hour+ late

1.9%

National rate is 8.1%

These figures cover 268 flights between July 2025 and June 2026. The median arrival is 10 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 1821 flies

UA 1821 flies IAH to RDU without a single fixed slot. Its most common scheduled departure was 12:00, used on 152 of 268 flights, with 12:10 (27 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 12:00152 flights56.7%
Departs 12:1027 flights10.1%

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 12:00 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and UA 1821 runs 15 points better at 93.6%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 1821 next to IAH to RDU

Every carrier on IAH to RDU combined arrived on time 82.2% of the time across 906 flights, so UA 1821 is 11 points ahead of it. United flew 700 flights on the same city pair under all its flight numbers, including this one, and those ran 83.9% on time. Across its whole network United Airlines managed 79.0%, which this flight beats by 15 points.

UA 1821 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1821thin sample	268	93.6%	54 min	1.12%	A
All United Airlines on IAH–RDU	700	83.9%	67 min	0.71%	B+
All carriers on IAH–RDU	906	82.2%	73 min	1.10%	B
United Airlines, whole network	821,041	79.0%	72 min	1.01%	B

Across the year

UA 1821 quarter by quarter

Quarter by quarter UA 1821 held fairly steady: 94.8% in Jul–Sep 2025, 92.3% in Oct–Dec 2025 and 94.3% in Jan–Mar 2026. A spread of 3 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202558 flights94.8%
Oct–Dec 202591 flights92.3%
Jan–Mar 202690 flights94.3%
Apr–Jun 202629 flights—

Scale runs 85% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1821 did best on Wednesday at 100.0% on time and worst on Sunday at 86.8%. Each day rests on about 38 flights, so a gap of 13 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 1821 runs late

One category carries most of the weight here. Carrier accounts for 47% of the 915 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.

Carrier
47%
Late-arriving aircraft
34%
National Airspace System
19%

The largest share of delay minutes, 47%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 432 of the 915 delay minutes reported here. The split is drawn from 915 delay minutes reported on UA 1821.

Cancellations sit at 1.12% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 1.9% 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.

The 1,042 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 three other city pairs in the data, including MSY to IAH (230), ORD to LGA (62) and RDU to EWR (49), but none flew often enough under UA 1821 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAH to RDU only.

One caution: this is a thin sample. 268 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 1821

For a booking, UA 1821 has one of the better records a US domestic flight can show: 93.6% on time and 1.12% 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