Route profile
SJU→DTW
Flight reliability, delays and best times to fly from San Juan to Detroit, 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 80% of comparable major US routes (4,598 compared)
Calculated from 1,204 flights. How this is calculated · What counts as on time
SJU → DTW arrives on time 82.9% of the time; the return trip, DTW → SJU, arrives on time 80.6% of the time, a 2.3-point gap between the two directions of the same city pair.
SJU → DTW spends 26.8 minutes on the ground on a 1,930-mile trip: 17.9 minutes from pushback to wheels-up at SJU and 9.0 minutes from touchdown to gate at DTW.
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 95% of 5,368 comparable routes.
82.4% on time over the most recent 12 months (2025-08 to 2026-07), against 82.7% 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.
What sets this route apart
Where SJU to DTW differs most from similar routes by hour, weekday, month and airline, July 2023 – July 2026.
SJU to DTW is at its best against routes of similar length for flights scheduled at 2 PM: 85.8% arrive on time, 11.3 points ahead of the 74.5% those routes manage at that hour. Against all other routes the gap is 11.2 points.
SJU to DTW holds up on Sundays better than routes of similar length do: 83.0% on time to their 75.6%, a 7.4 points lead. Against all other routes the gap is 8.2 points.
July is kinder to SJU to DTW than to routes of similar length: 84.6% on time against 70.3%, 14.3 points better. Against all other routes the gap is 14.9 points.
SJU to DTW against comparable routes
July 2023 – July 2026| Measure | This route | Compared with | Them | Gap | Flights behind it |
|---|---|---|---|---|---|
| Hour: 2 PM departures | 85.8% | routes of similar length | 74.5% | +11.3 pts | 394 here, 47,413 there |
| Weekday: Sunday | 83.0% | routes of similar length | 75.6% | +7.4 pts | 165 here, 161,519 there |
| Month: July | 84.6% | routes of similar length | 70.3% | +14.3 pts | 182 here, 133,271 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
32 min late
against a median of 8 min early
Percentiles over 1,204 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at DTW after arriving from SJU.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 35% | Likely to miss |
| 45 min | 16% | High risk |
| 60 min | 10% | Some risk |
| 90 min | 4.9% | Low risk |
| 120 min | 3.5% | 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 0.75% of the time and diverts 0.66% of the time, which a late arrival never shows up in.
Chance of missing is the share of 1,187 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 32 minutes late (90th-percentile gate arrival delay), over 1,204 operations.
Any other layover length: connection checker.
Why SJU → DTW 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 SJU → DTW. Only delays of 15 minutes or more are attributed. What the five causes mean
Late-arriving aircraft is the largest cause on SJU → DTW, at 47.0%: flights here mostly leave late because the plane came in late.
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 | 82.6% | 0.75% | -8 min | 4.9% |
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Friday the least, a gap of 5.9 percentage points.
Reliability over time
July 2023 – July 2026
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 82.4% against 82.7% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 1,204 SJU → DTW 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