Route profile
BOS→DEN
Flight reliability, delays and best times to fly from Boston to Denver, 1,754 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 55% of comparable major US routes (4,598 compared)
Calculated from 11,834 flights. How this is calculated
BOS → DEN arrives on time 78.2% of the time; the return trip, DEN → BOS, arrives on time 70.9% of the time, a 7.2-point gap between the two directions of the same city pair.
BOS → DEN spends 28.8 minutes on the ground on a 1,754-mile trip: 18.7 minutes from pushback to wheels-up at BOS and 10.0 minutes from touchdown to gate at DEN.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
Why BOS → DEN flights are cancelled
July 2023 – July 2026
BOS → DEN cancelled 137 of 11,834 scheduled flights — about 1 in every 86. The reason filed most often was the airline, 49.6% of the cancellations coded on this route — about 1 in every 174 scheduled flights.
Share of cancellations
Of 137 cancelled departures carrying a reason code.
What each reason means
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
68 cancellations, 49.6% of the total.
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
57 cancellations, 41.6% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
12 cancellations, 8.8% 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. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
137 coded cancellations were recorded on BOS → DEN; the section appears from 50.
When it goes wrong
July 2023 – July 2026
43 min late
against a median of 7 min early
Percentiles over 11,834 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at DEN after arriving from BOS.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 37% | Likely to miss |
| 45 min | 21% | High risk |
| 60 min | 13% | Some risk |
| 90 min | 7.0% | 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 1.16% of the time and diverts 0.30% of the time, which a late arrival never shows up in.
Chance of missing is the share of 11,661 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 43 minutes late (90th-percentile gate arrival delay), over 11,834 operations.
Any other layover length: connection checker.
Best time to fly
BOS → DEN flights departing 9 AM–12 PM arrived on time 87.5% of the time, against 59.4% for 6–9 PM departures, a gap of 28.1 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 90.7% on time from 506 flights
- 6 AM: 91.0% on time from 577 flights
- 7 AM: 85.3% on time from 2,382 flights
- 8 AM: 79.9% on time from 350 flights
- 9 AM: 89.5% on time from 1,018 flights
- 10 AM: 82.7% on time from 391 flights
- 11 AM: 87.4% on time from 1,141 flights
- 12 PM: 80.2% on time from 294 flights
- 1 PM: 77.5% on time from 288 flights
- 2 PM: 71.8% on time from 250 flights
- 3 PM: 79.0% on time from 1,248 flights
- 4 PM: 69.9% on time from 1,202 flights
- 5 PM: 45.0% on time from 314 flights
- 6 PM: 57.0% on time from 450 flights
- 7 PM: 57.1% on time from 454 flights
- 8 PM: 61.8% on time from 922 flights
- 9 PM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why BOS → DEN runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for BOS → DEN. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on BOS → DEN, at 41.9%: flights here mostly leave late because the plane came in late, and the day shows it: 9 AM–12 PM departures arrived on time 87.5% of the time and 6–9 PM departures 59.4%.
How this route holds up in bad weather
July 2023 – July 2026
Bad weather raises cancellations by a similar amount at both ends of BOS to DEN: 3.9 times the normal rate at BOS and 4.0 times at DEN. Cancelled in bad weather against normal hours: BOS 5.3% against 1.4%, DEN 2.8% against 0.7%. Flights that did leave DEN in bad weather arrived on time 51.5% of the time, against 78.8% in normal hours.
Bad weather and normal hours at the airports
Scheduled departures, July 2023 – July 2026| Departures from | BOS | DEN |
|---|---|---|
| Cancelled in bad weather | 5.3% | 2.8% |
| Cancelled in normal hours | 1.4% | 0.7% |
| Arrived on time, bad weather | 65.1% | 51.5% |
| Arrived on time, normal hours | 79.7% | 78.8% |
| Departures in bad weather | 60,840 | 92,610 |
Delta Air Lines (3.1% cancelled against 5.8% for the other carriers at BOS), Southwest Airlines (3.6% cancelled against 5.3% for the other carriers at BOS) and United Airlines (4.6% cancelled against 5.4% for the other carriers at BOS) cancelled fewer departures from BOS in bad weather than the other carriers there did in the same months. None of the route’s other carriers was clearly worse.
This route’s airlines in bad weather at BOS
All departures from BOS| Airline | Bad-weather departures | Cancelled | Other carriers |
|---|---|---|---|
| Delta Air Lines | 10,971 | 3.1%below the others | 5.8% |
| Southwest Airlines | 2,809 | 3.6%below the others | 5.3% |
| United Airlines | 5,328 | 4.6%below the others | 5.4% |
| JetBlue | 17,332 | 5.4%about level | 5.1% |
These are airport figures, not route figures: every scheduled departure from BOS and DEN, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from BOS on every route.
Weather source and limits. In full: BOS (airlines), DEN, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.
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 | 5,956 | 83.2% | 1.31% | -10 min | 5.3% |
| Southwest Airlines | 2,671 | 72.9% | 0.71% | -2 min | 8.7% |
| JetBlue | 1,943 | 71.0% | 1.24% | -5 min | 11.6% |
| Delta Air Lines | 1,264 | 76.6% | 1.27% | -4 min | 5.9% |
United Airlines flew 50.3% of the 11,834 flights listed.
United Airlines arrived on time 12.2 percentage points more often than JetBlue on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
UA662 (9:30 AM) arrived on time 91.0% of the time, 11.6 points more often than B6393 (10:00 AM) at 79.4%.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Friday the least, a gap of 6.6 percentage points.
By month
- Jan: 79.0%
- Feb: 76.8%
- Mar: 84.0%
- Apr: 77.9%
- May: 78.2%
- Jun: 72.3%
- Jul: 69.3%
- Aug: 74.4%
- Sep: 81.2%
- Oct: 82.5%
- Nov: 86.4%
- Dec: 84.4%
July is historically the weakest month and November the strongest, a spread of 17.1 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 57.8% from 345 flights
- August 2023: 72.3% from 358 flights
- September 2023: 82.6% from 315 flights
- October 2023: 81.4% from 318 flights
- November 2023: 87.7% from 253 flights
- December 2023: 95.6% from 274 flights
- January 2024: 80.5% from 247 flights
- February 2024: 90.4% from 223 flights
- March 2024: 86.3% from 259 flights
- April 2024: 81.0% from 254 flights
- May 2024: 77.3% from 313 flights
- June 2024: 75.8% from 367 flights
- July 2024: 76.5% from 388 flights
- August 2024: 71.9% from 411 flights
- September 2024: 88.1% from 354 flights
- October 2024: 88.7% from 362 flights
- November 2024: 84.2% from 311 flights
- December 2024: 85.0% from 303 flights
- January 2025: 83.6% from 275 flights
- February 2025: 62.4% from 251 flights
- March 2025: 89.7% from 321 flights
- April 2025: 69.0% from 303 flights
- May 2025: 76.5% from 350 flights
- June 2025: 70.2% from 384 flights
- July 2025: 68.5% from 427 flights
- August 2025: 78.8% from 397 flights
- September 2025: 72.5% from 333 flights
- October 2025: 77.1% from 342 flights
- November 2025: 87.7% from 293 flights
- December 2025: 73.5% from 301 flights
- January 2026: 72.7% from 259 flights
- February 2026: 79.3% from 266 flights
- March 2026: 75.8% from 300 flights
- April 2026: 84.5% from 284 flights
- May 2026: 80.7% from 323 flights
- June 2026: 71.0% from 374 flights
- July 2026: 73.0% from 396 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 77.0% against 78.0% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 11,834 BOS → DEN 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