Route profile
BOS→SLC
Flight reliability, delays and best times to fly from Boston to Salt Lake City, 2,105 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 54% of comparable major US routes (4,598 compared)
Calculated from 3,990 flights. How this is calculated
BOS → SLC arrives on time 78.6% of the time; the return trip, SLC → BOS, arrives on time 80.2% of the time.
BOS → SLC spends 30.7 minutes on the ground on a 2,105-mile trip: 22.7 minutes from pushback to wheels-up at BOS and 8.0 minutes from touchdown to gate at SLC.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
The airline matters unusually much on this route, a wider carrier-to-carrier gap than 94% of 2,692 comparable routes.
Delta Air Lines arrived on time 82.6% of the time, against 62.4% for JetBlue, flying the exact same route.
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 2,692 in the comparison.
What sets this route apart
Where BOS to SLC differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
In February, BOS to SLC runs 5.3 points below routes of similar length, 76.2% on time to 81.5%. Against all other routes the gap is 5.3 points.
JetBlue’s flights on BOS to SLC arrive on time 62.4% of the time, 11.6 points below the 74.0% it manages on its routes of similar length. Against all other routes the gap is 9.8 points.
BOS to SLC against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Month: February | 76.2% | routes of similar length | 81.5% | −5.3 pts | 282 here, 65,718 there |
| Airline: JetBlue | 62.4% | routes of similar length | 74.0% | −11.6 pts | 782 here, 45,298 there |
Each comparison pools the flights of other routes, with this route’s own left out. Similar length means within 15% of this route’s 2,105 miles, with at least 5 such routes. A bucket is set against the most comparable group that has enough flights: similar length, then the same origin (at least 3 routes), then all other routes. Hours, weekdays and months appear only where both sides have 120 completed flights, and airlines where both have 600. The gap must be at least 2 points and 2 standard errors, and only the largest gap each way is kept per measure. These are differences in the flights counted, not causes.
When it goes wrong
July 2023 – July 2026
42 min late
against a median of 6 min early
Percentiles over 3,990 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at SLC 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 | 7.2% | Some risk |
| 120 min | 4.6% | 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 0.88% of the time and diverts 0.25% of the time, which a late arrival never shows up in.
Chance of missing is the share of 3,945 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 42 minutes late (90th-percentile gate arrival delay), over 3,990 operations.
Any other layover length: connection checker.
Best time to fly
BOS → SLC flights departing 5–9 AM arrived on time 88.1% of the time, against 71.0% for 6–9 PM departures, a gap of 17.1 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 89.3% on time from 1,109 flights
- 7 AM to 8 AM: too few flights to score
- 9 AM: 82.7% on time from 164 flights
- 10 AM: 81.2% on time from 615 flights
- 11 AM: 81.0% on time from 148 flights
- 12 PM to 3 PM: too few flights to score
- 4 PM: 69.9% on time from 280 flights
- 5 PM: 74.3% on time from 300 flights
- 6 PM: 71.9% on time from 1,042 flights
- 7 PM: 65.0% on time from 204 flights
- 8 PM to 11 PM: too few flights to score
Departure windows with fewer than 120 flights are not scored.
Why BOS → SLC runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
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 → SLC. Only delays of 15 minutes or more are attributed.
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 |
|---|---|---|---|---|---|
| Delta Air Lines | 3,194 | 82.6% | 0.69% | -8 min | 5.5% |
| JetBlue | 796 | 62.4% | 1.63% | 4 min | 14.7% |
Delta Air Lines flew 80.1% of the 3,990 flights listed.
Delta Air Lines arrived on time 20.2 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.
DL859 (6:10 AM) arrived on time 88.3% of the time, 14.0 points more often than DL445 (6:45 PM) at 74.3%.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Sunday the least, a gap of 8.2 percentage points.
By month
- Jan: 78.7%
- Feb: 76.2%
- Mar: 77.3%
- Apr: 81.1%
- May: 79.9%
- Jun: 70.5%
- Jul: 72.0%
- Aug: 78.6%
- Sep: 86.8%
- Oct: 85.4%
- Nov: 85.2%
- Dec: 77.3%
June is historically the weakest month and September the strongest, a spread of 16.3 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 65.4% from 138 flights
- August 2023: 77.9% from 132 flights
- September 2023: too few flights to score (113)
- October 2023: too few flights to score (112)
- November 2023: too few flights to score (88)
- December 2023: too few flights to score (107)
- January 2024: too few flights to score (87)
- February 2024: too few flights to score (84)
- March 2024: too few flights to score (117)
- April 2024: 79.0% from 120 flights
- May 2024: 83.1% from 124 flights
- June 2024: 64.2% from 120 flights
- July 2024: 71.8% from 122 flights
- August 2024: 74.2% from 124 flights
- September 2024: too few flights to score (114)
- October 2024: too few flights to score (112)
- November 2024: too few flights to score (87)
- December 2024: too few flights to score (88)
- January 2025: too few flights to score (83)
- February 2025: too few flights to score (96)
- March 2025: 77.2% from 151 flights
- April 2025: too few flights to score (90)
- May 2025: too few flights to score (93)
- June 2025: too few flights to score (109)
- July 2025: 75.2% from 123 flights
- August 2025: too few flights to score (116)
- September 2025: too few flights to score (92)
- October 2025: too few flights to score (92)
- November 2025: too few flights to score (97)
- December 2025: too few flights to score (107)
- January 2026: too few flights to score (92)
- February 2026: too few flights to score (110)
- March 2026: 72.7% from 132 flights
- April 2026: too few flights to score (92)
- May 2026: too few flights to score (93)
- June 2026: too few flights to score (110)
- July 2026: 76.3% from 123 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 75.4% against 80.8% in the 12 months before — declining by 5.4 percentage points.
Data and methodology
Calculated by FlyerIntel from 3,990 BOS → SLC 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