Route on-time record
LAS to IAD: most on-time flights and the best time to fly
Las Vegas (Harry Reid International Airport) to Dulles (Washington Dulles International Airport). 1,130 nonstop flights in Jun 2025 to May 2026, 87% arrived within 15 minutes and 0.5% were cancelled. The most reliable flight number was United 688 at 8:10 AM.
Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.
LAS → IAD
Las Vegas to Dulles: 1,130 nonstop flights a year
On time (12 months)
87%
Cancelled
0.5%
avg delay 7 min
Best time to leave
Before 9 AM
92% on time vs 83% noon to 3 PM
Most reliable airline
United
88% chance on time
Lowest nonstop fare seen in the next two months: $118 (Frontier 4278 on 2026-11-20). Fares open on our travel partner (Aviasales). Pick the flight number you chose here.
Most reliable nonstop flights
Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.
#1 · United 688
8:10 AM → 3:49 PM4h 39m nonstop
Local times, typical schedule. Last flown 2026-05-20.
91%
chance on time
- On time (history)
- 92%
- Cancelled
- 0.0%
- Avg arrival delay
- 4 min
- Arrived on time 92% of the time (53 flights, Jun 2025 to May 2026).
- Never cancelled in 53 scheduled flights.
- Leaves in this route's most on-time window (Before 9 AM: 92% on time; Noon to 3 PM: 83%).
- Departs outside LAS's trouble window (10 AM to 4 PM, when 51% of its 107 ground stops and delay programs started).
Limited track record · 53 flights
Find United 688 fares Opens this date on Aviasales#2 · United 2175
11:40 PM → 7:17 AM4h 37m nonstop
Local times, typical schedule. Last flown 2026-05-20.
89%
chance on time
- On time (history)
- 93%
- Cancelled
- 0.0%
- Avg arrival delay
- 8 min
- Arrived on time 93% of the time (14 flights, Jun 2025 to May 2026).
- Departs outside LAS's trouble window (10 AM to 4 PM, when 51% of its 107 ground stops and delay programs started).
Limited track record · 14 flights
Find United 2175 fares Opens this date on Aviasales#3 · United 1140
8:48 AM → 4:24 PM4h 36m nonstop
Local times, typical schedule. Last flown 2026-05-31.
89%
chance on time
- On time (history)
- 82%
- Cancelled
- 0.0%
- Avg arrival delay
- 15 min
- Arrived on time 82% of the time (11 flights, Jun 2025 to May 2026).
- Leaves in this route's most on-time window (Before 9 AM: 92% on time; Noon to 3 PM: 83%).
- Departs outside LAS's trouble window (10 AM to 4 PM, when 51% of its 107 ground stops and delay programs started).
- Lands inside IAD's trouble window: 75% of its 63 ground stops and delay programs started between 1 PM and 7 PM.
Limited track record · 11 flights
Find United 1140 fares Opens this date on Aviasales#4 · United 2382
1:11 PM → 8:54 PM4h 43m nonstop
Local times, typical schedule. Last flown 2026-05-31.
84%
chance on time
- On time (history)
- 84%
- Cancelled
- 0.6%
- Avg arrival delay
- 9 min
- Arrived on time 84% of the time (304 flights, Jun 2025 to May 2026).
- Leaves in this route's least on-time window (Noon to 3 PM: 83% on time; Before 9 AM: 92%).
- Departs inside LAS's trouble window: 51% of its 107 ground stops and delay programs started between 10 AM and 4 PM.
Strong track record · 304 flights
Find United 2382 fares Opens this date on Aviasales#5 · Frontier 4278
12:35 AM → 8:12 AM4h 37m nonstop
Local times, typical schedule. Last flown 2026-05-31.
78%
chance on time
- On time (history)
- 72%
- Cancelled
- 0.0%
- Avg arrival delay
- 17 min
- Arrived on time 72% of the time (93 flights, Jun 2025 to May 2026).
- Never cancelled in 93 scheduled flights.
- Departs outside LAS's trouble window (10 AM to 4 PM, when 51% of its 107 ground stops and delay programs started).
Moderate track record · 93 flights
Find Frontier 4278 fares Opens this date on Aviasales
Airlines on this route
Season-adjusted chance of operating and arriving on time.
- United Airlines88%
1,037 flights · 88% on time as flown · 0.6% cancel
- Frontier Airlines81%
93 flights · 72% on time as flown · 0.3% cancel
On time by departure time
All airlines, scheduled local departure, Jun 2025 to May 2026.
- Before 9 AM92%
361 flights · avg delay 4 min
- Noon to 3 PM83%
361 flights · avg delay 10 min
- After 9 PM86%
407 flights · avg delay 8 min
Best day: Tuesday (91%). Worst: Sunday (81%).
On time by month
All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.
What delays this route
- Airline (crew, maintenance, boarding)41%
- Late-arriving aircraft32%
- Air traffic control and airport volume26%
Share of delay minutes by the cause airlines report to the US DOT.
Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure
LAS to IAD questions
- What time of day is best to fly LAS to IAD?
- Before 9 AM: 92% of flights arrived on time, against 83% for departures noon to 3 PM. Later flights inherit delays from earlier ones, so the first departures of the day usually run best.
- Which airline is most on time from LAS to IAD?
- United, with a season-adjusted 88% chance of operating and arriving on time over 1,037 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
- What is the worst month for delays on LAS to IAD?
- July (73% on time); the best was October (93%), averaged over Jun 2023 to May 2026.
- Is this a prediction for my flight?
- No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.
More routes from LAS
- IAD to LAS (return)
- LAS to LAX 79%
- LAS to DEN 77%
- LAS to SAN 68%
- LAS to PHX 78%
- LAS to SFO 66%
- LAS to SEA 82%
- LAS to ORD 77%
- LAS to DFW 81%
- LAS to ATL 84%
- LAS to SNA 82%
- LAS to SMF 79%
- LAS to BUR 80%
Most on-time flights from LAS on every route →
Live status: FAA delays and ground stops