Route reliability record
DTW→SAN
Detroit to San Diego
- Flights
- 1,314
- Period
- July 2025 to June 2026
- Distance
- 1,956 mi
- Carriers
- 2
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,314 DTW to SAN flights, with a median arrival 1 minute early.
Best time to fly DTW to SAN: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 82.8% of the time and Tuesday flights 82.0%, against 75.4% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.4%
Arrivals under 15 minutes late, of 1,293 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.07%
National rate is 1.81%
Best carrier
Delta
74.9% on time across 1,260 flights
These figures cover 1,314 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Which airline is most reliable on DTW to SAN
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Spirit Airlinesthin sample | 54 | 88.5% | 33 min | 1.85% | A |
| Delta Air Lines | 1,260 | 74.9% | 58 min | 1.03% | C |
Flight by flight
Flights on DTW to SAN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am419 flights82.8%
- 11am–2pm260 flights81.3%
- 2pm–5pm317 flights74.4%
- 5pm–8pm47 flights57.8%
- 8pm–5am271 flights62.4%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 57.8% on time, against 82.8% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 419 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 28 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
January is the weak month at 57.1% on time, against 84.7% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 133 flights.
Across the week, Tuesday is the strongest day at 82.0% on time and Sunday the weakest at 71.7%. 10 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 18,000 reported delay minutes.
- 41%Carrier
- 30%National Airspace System
- 27%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 7,511 of the 18,000 delay minutes reported here. The split is drawn from 18,341 reported delay minutes.
Cancellations sit at 1.07% against a national 1.81%, which is ordinary. Diversions add another 0.53%.
Connections and stage length
What a delay here actually costs
6.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 1,956 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 85.8% on time across 1,314 flights, 10 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 10 points of difference.
The sample behind these figures is 1,314 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in SAN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 84.7% on time and January 57.1%, a swing of 28 points. If the dates move at all, move them out of January before you think about anything else. 1,293 completed flights over 12 months sit behind that.
Common questions
DTW to SAN questions
How often is DTW to SAN delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.6% of the 1,314 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is DTW to SAN compared with the rest of the country?
75.4% of flights arrive on time here against a national 77.6%, a difference of 2 points against it. That is worth a B on this site's grading scale.
What time of day has the fewest delays on DTW to SAN?
The 8am–11am departure window is the strongest at 82.8% on time. The 5pm–8pm window is the weakest at 57.8%, 25 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are January delays on DTW to SAN?
January is the weakest month at 57.1% on time, compared with 84.7% in October. Across the year that is 28 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- SAN to DTW — the return legseparate record
- Detroit Metropolitan Wayne County (DTW) delay statistics
- San Diego International (SAN) delay statistics
- DTW to ORD, a related route72.0%
- SFO to SAN, a related route66.6%
- DTW to ATL, a related route79.0%
- Spirit Airlines on-time record88.5%
- Delta Air Lines on-time record74.9%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. DTW to SAN and SAN to DTW are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.