Route profile
DTW→SJU
Flight reliability, delays and best times to fly from Detroit to San Juan, 1,930 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 85% of comparable major US routes (4,598 compared)
Calculated from 1,203 flights. How this is calculated
DTW → SJU arrives on time 80.6% of the time; the return trip, SJU → DTW, arrives on time 82.9% of the time, a 2.3-point gap between the two directions of the same city pair.
DTW → SJU spends 27.5 minutes on the ground on a 1,930-mile trip: 20.5 minutes from pushback to wheels-up at DTW and 7.0 minutes from touchdown to gate at SJU.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What sets this route apart
Where DTW to SJU differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
DTW to SJU struggles most at 8 AM: 80.0% of its flights scheduled then arrive on time, 3.6 points behind the 83.6% on routes of similar length at the same hour. Against all other routes the gap is 5.9 points.
July is kinder to DTW to SJU than to routes of similar length: 79.9% on time against 70.3%, 9.6 points better. Against all other routes the gap is 10.2 points.
DTW to SJU against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 8 AM departures | 80.0% | routes of similar length | 83.6% | −3.6 pts | 654 here, 79,244 there |
| Month: July | 79.9% | routes of similar length | 70.3% | +9.6 pts | 184 here, 133,269 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 1,930 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
30 min late
against a median of 3 min early
Percentiles over 1,203 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at SJU after arriving from DTW.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 41% | Likely to miss |
| 45 min | 19% | High risk |
| 60 min | 9.9% | Some risk |
| 90 min | 4.3% | Low risk |
| 120 min | 2.7% | 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 0.25% of the time and diverts 0.50% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,194 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 30 minutes late (90th-percentile gate arrival delay), over 1,203 operations.
Any other layover length: connection checker.
Why DTW → SJU runs late
July 2023 – July 2026
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
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 DTW → SJU. 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 | 1,062 | 80.2% | 0.28% | -3 min | 4.2% |
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
| Flight | Scheduled | Operations | On time |
|---|---|---|---|
| DL1913 Delta Air Lines | 8:35 AM | 899 | 79.5% |
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Monday the least, a gap of 7.6 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 75.8% against 78.8% in the 12 months before — declining by 3.0 percentage points.
Data and methodology
Calculated by FlyerIntel from 1,203 DTW → SJU 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