Washington (IAD) to Boston (BOS): On-Time Performance
Data through July 2026
The calendar drives reliability on IAD–BOS. October 2024 flights landed on schedule 90% of the time, but September 2025 dropped to 58% — a gap of 32 points. Across the full period the route averages 77% on-time against a national 78%. Morning departures also hold up better than evening ones (91% vs 70%), which matters most in the rough months.
- On-time
- 77%
- arrived <15 min late
- Avg delay
- 19 min
- completed flights
- Cancelled
- 1.6%
- Flights/day
- 4.1
- last 12 months
- Duration
- 1h 40m
- scheduled
- Distance
- 412 mi
Best airline from IAD to BOS
2 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 77% | 19 min | 1.4% | 3,123 |
| Republic Airways | 76% | 16 min | 12.1% | 66 |
Monthly on-time trend
Best time to fly from IAD to BOS
Aim for departures around 8 a.m. (91% on-time); avoid 3 p.m. departures (55%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 73% | 20 min |
| Tuesday | 80% | 17 min |
| Wednesday | 77% | 18 min |
| Thursday | 71% | 27 min |
| Friday | 79% | 19 min |
| Saturdaybest | 83% | 14 min |
| Sunday | 75% | 18 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft26%
- Airline operations20%
- National airspace system46%
- Weather8%
Frequently asked questions
- How often are flights from IAD to BOS delayed?
- 23% of IAD–BOS flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 19 minutes.
- Which airline is most reliable from IAD to BOS?
- United Airlines has the best on-time record on this route at 77%, based on 3,123 flights. 2 airlines flew IAD–BOS frequently enough to compare in this period.
- What is the best time of day to fly from IAD to BOS?
- Departures around 8 a.m. have the best record (91% on-time), while departures around 3 p.m. have the worst (55%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from IAD to BOS?
- The scheduled IAD–BOS flight time averages 1h 40m over 412 miles. Actual arrival times vary — flights on this route land 15+ minutes late 23% of the time.
- How often are IAD to BOS flights cancelled?
- 1.6% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from IAD to BOS?
- September 2025 was the roughest month in this dataset, with only 58% of arrivals on time. The best was October 2024 at 90%. If your dates are flexible, that 32-point gap is worth planning around.
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Based on 3,189 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.