Routes › Boston (BOS) › BOS to SJU
Route · 12 months to July 2026
Boston to San Juan: on-time record
Logan International to Luis Munoz Marin International
BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report. Data through July 2026; this is a monthly history, not live flight status.
In the 12 months to July 2026, reporting carriers scheduled 1,770 flights from Boston (BOS) to San Juan (SJU), a distance of 1,674 miles. 65.3% of them arrived within 15 minutes of schedule.
That is 10.7 points below the national on-time share of 76.0% for the same period and 8.0 points below the 73.3% recorded for all departures from BOS. Flights that did arrive were 18.4 min late on average, and 2.9% of scheduled flights were cancelled (national: 1.8%).
3 reporting carriers flew the route at least 60 times. Delta Air Lines had the highest on-time share at 73.6% of 398 flights; Spirit Airlines had the lowest at 48.6% of 146.
By scheduled departure hour (local time at BOS), flights leaving from 8 am to 9 am had the highest on-time share, 77.6%; those leaving from 9 pm to 10 pm had the lowest, 28.6%.
The on-time share is down 1.9 points on the previous 12 months (67.2%); cancellations moved from 1.0% to 2.9%.
Of the delay minutes that carriers assigned to a BTS cause category on this route, national aviation system 35%, late-arriving aircraft 32% and air carrier 30%.
- On time 65.3%
- Arrived 15+ minutes late 31.6%
- Cancelled 2.9%
- Diverted 0.2%
Airlines on the route compared
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| B6 JetBlue Airways | 1,192 | 67% | 65.2% | 17.4 min | 2.8% |
| DL Delta Air Lines | 398 | 22% | 73.6% | 8.3 min | 1.5% |
| NK Spirit Airlines | 146 | 8% | 48.6% | 44.7 min | 8.2% |
| F9 Frontier Airlines | 34 | 2% | 41.2% | 65.7 min | 2.9% |
Carriers with at least 24 flights in the 12 months to July 2026. The on-time pill is green when a carrier is at or above the route's overall share. Regional carriers operate flights sold under larger airlines' brands; BTS lists the carrier that operated the flight.
Compared with the airports and the nation
| Measure | BOS to SJU | All departures from BOS | All arrivals at SJU | All reported flights |
|---|---|---|---|---|
| Arrived on time | 65.3% | 73.3% | 69.9% | 76.0% |
| Arrived 15+ minutes late | 31.6% | 23.6% | 28.0% | 21.9% |
| Cancelled | 2.9% | 2.8% | 1.9% | 1.8% |
| Diverted | 0.2% | 0.3% | 0.2% | 0.3% |
| Average arrival delay | 18.4 min | 8.1 min | 14.3 min | 8.1 min |
| Delay minutes per 100 flights | 2,460 | 1,788 | 2,089 | 1,684 |
| Scheduled flights | 1,770 | 143,447 | 35,303 | 7,043,858 |
12 months to July 2026. Delay minutes count late arrivals only (an early arrival is zero), so the per-100-flights row is a normalised total rather than an average of early and late.
The return direction, SJU to BOS, recorded 68.5% on time across 1,961 flights in the same period.
Month by month
Year on year: on time 65.3% against 67.2% (−1.9 pts), cancelled 2.9% against 1.0%, flights 1,770 against 2,048.
By scheduled departure hour
Delay causes
Seasonality
| Calendar month | Flights | On time | Cancelled | Avg arrival delay | Years in sample |
|---|---|---|---|---|---|
| Jan | 506 | 60.7% | 4.5% | 22.6 min | 3 |
| Feb | 521 | 56.0% | 3.3% | 35.3 min | 3 |
| Mar | 579 | 68.2% | 1.6% | 15.1 min | 3 |
| Apr | 551 | 72.1% | 0.7% | 12.9 min | 3 |
| May | 453 | 75.7% | 0.7% | 7.7 min | 3 |
| Jun | 498 | 72.9% | 0.4% | 11.3 min | 3 |
| Jul | 531 | 66.9% | 3.2% | 20.6 min | 3 |
| Aug | 580 | 60.7% | 1.7% | 25.3 min | 3 |
| Sep | 318 | 74.5% | 1.3% | 4.7 min | 3 |
| Oct | 355 | 71.8% | 0.8% | 5.0 min | 3 |
| Nov | 417 | 69.3% | 0.5% | 13.3 min | 3 |
| Dec | 510 | 59.2% | 0.4% | 25.5 min | 3 |
Each calendar month summed across the 36 months on file, so most rows combine three years. The pill compares the month with the route's own 12-month share.
Other routes from Boston (BOS)
| Route | Cities | Flights | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| BOS–DCA | Boston to Washington | 9,092 | 70.6% | 11.1 min | 3.8% |
| BOS–ORD | Boston to Chicago | 7,750 | 70.5% | 14.2 min | 3.0% |
| BOS–LGA | Boston to New York | 7,342 | 72.7% | 8.1 min | 5.8% |
| BOS–JFK | Boston to New York | 5,672 | 71.7% | 8.2 min | 4.8% |
| BOS–PHL | Boston to Philadelphia | 4,981 | 74.1% | 10.3 min | 3.1% |
| BOS–ATL | Boston to Atlanta | 4,973 | 76.0% | 6.1 min | 2.2% |
| BOS–LAX | Boston to Los Angeles | 4,758 | 73.6% | 10.3 min | 1.7% |
| BOS–SFO | Boston to San Francisco | 4,735 | 70.2% | 9.3 min | 1.5% |
All 83 routes and the airport record for BOS · airport record for SJU
Questions and answers
How often are flights from Boston to San Juan on time?
65.3% of the 1,770 flights scheduled from BOS to SJU in the 12 months to July 2026 arrived less than 15 minutes after their scheduled time. The national share for the same period was 76.0%. Cancelled and diverted flights count as not on time.
Which airline has the highest on-time share from BOS to SJU?
Among reporting carriers with at least 60 flights on the route, Delta Air Lines had the highest on-time share (73.6%), followed by JetBlue Airways (65.2%) and Spirit Airlines (48.6%). Differences of a point or two on a few hundred flights are small.
What causes delays between Boston and San Juan?
For flights that arrived 15 or more minutes late, carriers attributed the delay minutes as follows: national aviation system 35%, late-arriving aircraft 32%, air carrier 30%, extreme weather 2%, security 0%. The categories are the carriers' own reports to BTS; weather that slows the wider system is usually recorded under the National Aviation System rather than extreme weather.
What time of day has the highest on-time share from BOS?
Flights scheduled to leave BOS from 8 am to 9 am arrived on time 77.6% of the time, the highest of any hour with enough flights to compare. The lowest was 9 pm to 10 pm at 28.6%. Delays tend to build through the day as late aircraft carry over to later flights.
Is it getting better?
The on-time share for the 12 months to July 2026 was 65.3%, down 1.9 points on the previous 12 months (67.2%). The monthly chart on this page shows each of the last 36 months. Across those months, May had the highest on-time share (75.7%) and February the lowest (56.0%).
Where does this data come from?
Every figure is computed from the Bureau of Transportation Statistics Reporting Carrier On-Time Performance files, which list each scheduled domestic flight by the carriers required to report. This page covers August 2023 to July 2026. It shows totals and averages only; it is not a live flight-status service.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987 to present), monthly files August 2023 to July 2026, a US government work in the public domain. Figures are totals and averages over all scheduled flights by reporting carriers on the route; no individual flight or aircraft is identified. Times are local to the departure airport. The load factor and passenger counts from the BTS T-100 series are not included in this edition. See the methodology; report processing errors through corrections.