Route profile
BOS→IAD
Flight reliability, delays and best times to fly from Boston to Washington, 413 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 63% of comparable major US routes (4,598 compared)
Calculated from 4,652 flights. How this is calculated
BOS → IAD arrives on time 83.4% of the time; the return trip, IAD → BOS, arrives on time 77.5% of the time, a 5.9-point gap between the two directions of the same city pair.
BOS → IAD spends 24.4 minutes on the ground on a 413-mile trip: 18.3 minutes from pushback to wheels-up at BOS and 6.1 minutes from touchdown to gate at IAD.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route has stayed remarkably steady year over year, a smaller swing than 93% of 5,368 comparable routes.
83.5% on time over the most recent 12 months (2025-08 to 2026-07), against 83.1% in the 12 months before (2024-08 to 2025-07), virtually unchanged.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.
Why BOS → IAD flights are cancelled
July 2023 – July 2026
BOS → IAD cancelled 70 of 4,652 scheduled flights — about 1 in every 66. The reason filed most often was extreme weather, 75.7% of the cancellations coded on this route — about 1 in every 88 scheduled flights.
Share of cancellations
Of 70 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
53 cancellations, 75.7% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
9 cancellations, 12.9% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
8 cancellations, 11.4% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. With only one or two carriers on the route, the split mostly reflects how they file. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
70 coded cancellations were recorded on BOS → IAD; the section appears from 50.
When it goes wrong
July 2023 – July 2026
34 min late
against a median of 9 min early
Percentiles over 4,652 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at IAD after arriving from BOS.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 28% | High risk |
| 45 min | 16% | High risk |
| 60 min | 11% | Some risk |
| 90 min | 6.2% | Some risk |
| 120 min | 3.9% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.50% of the time and diverts 0.11% of the time, which a late arrival never shows up in.
Chance of missing is the share of 4,577 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 34 minutes late (90th-percentile gate arrival delay), over 4,652 operations.
Any other layover length: connection checker.
Best time to fly
BOS → IAD flights departing 5–9 AM arrived on time 96.1% of the time, against 71.6% for 6–9 PM departures, a gap of 24.5 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 96.1% on time from 1,112 flights
- 6 AM to 8 AM: too few flights to score
- 9 AM: 91.0% on time from 1,126 flights
- 10 AM to 1 PM: too few flights to score
- 2 PM: 73.9% on time from 1,125 flights
- 3 PM to 5 PM: too few flights to score
- 6 PM: 77.5% on time from 128 flights
- 7 PM: 70.9% on time from 1,012 flights
- 8 PM to 11 PM: too few flights to score
Why BOS → IAD runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for BOS → IAD. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on BOS → IAD, at 42.1%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 96.1% of the time and 6–9 PM departures 71.6%.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| United Airlines | 4,586 | 83.5% | 1.35% | -9 min | 6.2% |
Other ways to fly Boston to Washington
Airport pairs in the same two city markets, as the DOT defines them.
BOS → IAD is the most reliable pairing for this journey at 83.4% on time, against 77.3% for BOS → DCA.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
UA1734 (5:30 AM) arrived on time 96.1% of the time, 24.6 points more often than UA2136 (7:20 PM) at 71.5%.
Weekly and seasonal patterns
By day of week
Saturday is historically the most reliable day and Friday the least, a gap of 5.6 percentage points.
By month
- Jan: 81.7%
- Feb: 90.0%
- Mar: 86.3%
- Apr: 86.0%
- May: 85.8%
- Jun: 79.2%
- Jul: 72.7%
- Aug: 80.5%
- Sep: 85.3%
- Oct: 85.1%
- Nov: 86.5%
- Dec: 87.2%
July is historically the weakest month and February the strongest, a spread of 17.3 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 62.0% from 124 flights
- August 2023: 79.0% from 124 flights
- September 2023: too few flights to score (119)
- October 2023: 93.5% from 123 flights
- November 2023: too few flights to score (119)
- December 2023: 91.8% from 124 flights
- January 2024: 79.2% from 124 flights
- February 2024: too few flights to score (116)
- March 2024: 83.9% from 124 flights
- April 2024: 89.2% from 120 flights
- May 2024: 88.7% from 124 flights
- June 2024: 79.2% from 120 flights
- July 2024: 75.6% from 124 flights
- August 2024: 83.1% from 124 flights
- September 2024: 93.3% from 120 flights
- October 2024: 88.7% from 124 flights
- November 2024: too few flights to score (119)
- December 2024: 86.2% from 124 flights
- January 2025: 81.1% from 124 flights
- February 2025: too few flights to score (112)
- March 2025: 87.2% from 125 flights
- April 2025: 82.5% from 154 flights
- May 2025: 80.6% from 155 flights
- June 2025: 76.0% from 146 flights
- July 2025: 71.9% from 124 flights
- August 2025: 79.7% from 133 flights
- September 2025: 81.6% from 143 flights
- October 2025: 73.2% from 124 flights
- November 2025: too few flights to score (119)
- December 2025: 83.6% from 122 flights
- January 2026: too few flights to score (112)
- February 2026: too few flights to score (104)
- March 2026: too few flights to score (119)
- April 2026: 87.5% from 120 flights
- May 2026: 89.3% from 124 flights
- June 2026: 83.1% from 120 flights
- July 2026: 79.1% from 176 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 83.5% against 83.1% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 4,652 BOS → IAD flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed