Route reliability record
LAS→IAD
Las Vegas to Washington
- Flights
- 1,109
- Period
- July 2025 to June 2026
- Distance
- 2,065 mi
- Carriers
- 2
This route 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 roughly 55 minutes. That rests on 1,109 LAS to IAD flights, with a median arrival 13 minutes early.
Best time to fly LAS to IAD: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 90.8% of the time and Tuesday flights 91.8%, against 87.1% for the route overall.
Set against the rest of the country, this route'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.
Key figures
On time
87.1%
Arrivals under 15 minutes late, of 1,097 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.54%
National rate is 1.81%
Best carrier
United
88.8% on time across 1,011 flights
These figures cover 1,109 flights between July 2025 and June 2026. The median arrival is 13 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.
Carrier by carrier
Which airline is most reliable on LAS to IAD
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,011 | 88.8% | 51 min | 0.59% | A+ |
| Frontier Airlinesthin sample | 98 | 70.4% | 60 min | 0.00% | C+ |
Flight by flight
Flights on LAS to IAD
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Las Vegas to Washington
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 3 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. LAS → IADLas Vegas to Washington | United Airlines | 88.3% | 88.8% | 0.59% | 8am–11am, Tue (route) | UA 2382 13:15 |
| 2. LAS → DCALas Vegas to Washington | American Airlines | 78.1% | 79.2% | 1.37% | 11am–2pm, Sat | — |
| 3. LAS → BWILas Vegas to Baltimore | Southwest Airlines | 77.8% | 78.5% | 0.92% | 5am–8am, Sat | — |
| 4. LAS → DCALas Vegas to Washington | Southwest Airlines | 71.4% | 71.8% | 0.55% | 8am–11am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 10 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am361 flights90.8%
- 11am–2pm267 flights85.6%
- 2pm–5pm99 flights80.4%
- 5pm–8pm—
- 8pm–5am382 flights86.5%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 90.8% of the time, against 80.4% for the afternoon window. That is 10 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 382 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 21 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 73.9% on time, 21 points below October, the best at 94.6%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 123 flights.
Across the week, Tuesday is the strongest day at 91.8% on time and Sunday the weakest at 83.0%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 45% of the 7,412 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.
- 45%Carrier
- 32%Late-arriving aircraft
- 23%National Airspace System
- 0%Extreme weather
The largest share of delay minutes, 45%, 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 3,351 of the 7,412 delay minutes reported here. The split is drawn from 7,412 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 90.8% on time here.
Cancellations are rare at 0.54%, 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 stage length
What a delay here actually costs
Badly late arrivals are rare here: only 3.5% 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 2,065 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 return leg runs 85.1% on time across 1,108 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 1,109 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in IAD after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 94.6% on time and June 73.9%, a swing of 21 points. If the dates move at all, move them out of June before you think about anything else. 1,097 completed flights over 12 months sit behind that.
Common questions
LAS to IAD questions
How often is LAS to IAD delayed?
About one flight in eight arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 12.9% of the 1,109 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.
How reliable is LAS to IAD compared with the rest of the country?
87.1% of flights arrive on time here against a national 77.6%, a difference of 10 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on LAS to IAD?
The 8am–11am departure window is the strongest at 90.8% on time. The 2pm–5pm window is the weakest at 80.4%, 10 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on LAS to IAD?
June is the weakest month at 73.9% on time, compared with 94.6% in October. Across the year that is 21 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- IAD to LAS — the return legseparate record
- Harry Reid International (LAS) delay statistics
- Washington Dulles International (IAD) delay statistics
- LAS to LAX, a related route78.8%
- ATL to IAD, a related route76.5%
- LAS to DEN, a related route77.0%
- United Airlines on-time record88.8%
- Frontier Airlines on-time record70.4%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. LAS to IAD and IAD to LAS are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.