Flight number record
DL 866
Delta Air Lines · Detroit to Miami
- Route
- DTW → MIA
- Departs
- 13:59
- Flights
- 255
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 866, check with Delta Air Lines.
DL 866 sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land about 55 minutes behind schedule. That rests on 255 flights, with a median arrival 7 minutes early.
Key figures
On time
74.0%
Arrivals under 15 minutes late, of 250 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.89%
1 hour+ late
7.6%
National rate is 8.3%
These figures cover 255 flights between September 2025 and August 2026. The median arrival is 7 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Schedule
When DL 866 flies
DL 866 flies DTW to MIA without a single fixed slot. Its most common scheduled departure was 13:59, used on 36 of 255 flights, with 14:30 (31 flights) and 14:43 (30 flights) next.
- Departs 13:5936 flights14.1%
- Departs 14:3031 flights12.2%
- Departs 14:4330 flights11.8%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 13:59 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 866 runs 4 points worse at 74.0%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Against the route
DL 866 next to DTW to MIA
Every carrier on DTW to MIA combined arrived on time 80.7% of the time across 1,757 flights, so DL 866 is 7 points behind it. Delta flew 929 flights on the same city pair under all its flight numbers, including this one, and those ran 79.1% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 866thin sample | 255 | 74.0% | 55 min | 1.18% | C |
| All Delta Air Lines on DTW–MIA | 929 | 79.1% | 55 min | 1.08% | B |
| All carriers on DTW–MIA | 1,757 | 80.7% | 63 min | 1.42% | B |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 866 quarter by quarter
Quarter by quarter DL 866 held fairly steady: 71.6% in Jan–Mar 2026, 78.9% in Apr–Jun 2026 and 75.0% in Jul–Sep 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Oct–Dec 202512 flights—
- Jan–Mar 202690 flights71.6%
- Apr–Jun 202691 flights78.9%
- Jul–Sep 202662 flights75.0%
Scale runs 65% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, DL 866 did best on Tuesday at 82.9% on time and worst on Saturday at 67.6%. Each day rests on about 36 flights, so a gap of 15 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 866 runs when it is late
DL 866 often beats the schedule: 73 of 250 completed flights, 29%, arrived 15 minutes or more early. The 65 late arrivals split 23 under half an hour, 23 between 30 and 60 minutes, and 19 an hour or more.
- 15+ min early73 flights29.2%
- Within 15 min112 flights44.8%
- 15–29 min late23 flights9.2%
- 30–59 min late23 flights9.2%
- 1–2 hours late13 flights5.2%
- 2+ hours late6 flights2.4%
Scale runs 0% to 100%.
Share of 250 completed flights by arrival against schedule.
14 of 51 late departures made up the time and arrived on time, 27% of them. In the other direction, 28 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at MIA.
The worst days
Worst days for DL 866
The latest arrival of the period was on 7 July 2026, 4 hours 58 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in July 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 July 2026 | 4 hours 58 minutes | Carrier |
| 24 January 2026 | 3 hours 26 minutes | Carrier |
| 20 June 2026 | 3 hours 16 minutes | Carrier |
| 5 July 2026 | 2 hours 22 minutes | Late-arriving aircraft |
| 6 July 2026 | 2 hours 16 minutes | Carrier |
Delay causes
Why DL 866 runs late
Carrier accounts for 49% of the 3,550 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Carrier
- 36%National Airspace System
- 13%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 49%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,750 of the 3,550 delay minutes reported here. The split is drawn from 3,550 delay minutes reported on DL 866.
Cancellations sit at 1.18% against a national 1.89%, which is ordinary. Diversions add another 0.78%.
Connections and routes
What a delay on this flight costs
7.6% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.
The 1,145 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The same number turns up on three other city pairs in the data, including MIA to DTW (177), JAN to ATL (109) and ATL to JAN (109), but none flew often enough under DL 866 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to DTW to MIA only.
One caution: this is a thin sample. 255 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking DL 866
For a booking, DL 866 is one of the weaker ways to fly DTW to MIA: 7 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- DTW to MIA, every carrier and departure
- MIA to DTW, the return direction
- American Airlines 1020 on the same route89.4%
- Delta Air Lines 1468 on the same route85.4%
- Detroit Metropolitan Wayne County (DTW) delay statistics
- Miami International (MIA) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- The best time of day to fly, according to 7.05 million flight records
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.