Flight number record
DL 1187
Delta Air Lines · Detroit to Boston
- Route
- DTW → BOS
- Departs
- 21:50
- Flights
- 361
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1187, check with Delta Air Lines.
DL 1187 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.3%. The late ones land a little over an hour behind schedule. That rests on 361 flights, with a median arrival 6 minutes early.
The national on-time rate over the same period is 77.3%, so DL 1187 runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.
Key figures
On time
70.3%
Arrivals under 15 minutes late, of 354 completed flights
Avg delay
69 min
Across delayed arrivals only, not all flights
Cancelled
1.94%
National rate is 1.89%
1 hour+ late
12.4%
National rate is 8.3%
These figures cover 361 flights between September 2025 and August 2026. Beyond the headline rate, 12.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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 1187 flies
DL 1187 flies DTW to BOS without a single fixed slot. Its most common scheduled departure was 21:50, used on 82 of 361 flights, with 21:59 (68 flights) and 21:56 (60 flights) next.
- Departs 21:5082 flights22.7%
- Departs 21:5968 flights18.8%
- Departs 21:5660 flights16.6%
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 21:50 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and DL 1187 runs level with that at 70.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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 1187 next to DTW to BOS
Every carrier on DTW to BOS combined arrived on time 73.6% of the time across 2,572 flights, so DL 1187 is 3 points behind it. Delta flew 1,716 flights on the same city pair under all its flight numbers, including this one, and those ran 74.6% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 11 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1187thin sample | 361 | 70.3% | 69 min | 1.94% | C |
| All Delta Air Lines on DTW–BOS | 1,716 | 74.6% | 65 min | 1.98% | C |
| All carriers on DTW–BOS | 2,572 | 73.6% | 71 min | 2.72% | C |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1187 quarter by quarter
DL 1187 did not run the same all year. Its best quarter was Jan–Mar 2026 at 75.6% on time and its weakest Jul–Sep 2026 at 51.7%, a swing of 24 points on roughly 90 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202529 flights—
- Oct–Dec 202591 flights72.2%
- Jan–Mar 202690 flights75.6%
- Apr–Jun 202690 flights74.2%
- Jul–Sep 202661 flights51.7%
Scale runs 45% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, DL 1187 did best on Saturday at 77.6% on time and worst on Sunday at 58.3%. Each day rests on about 52 flights, so a gap of 19 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1187 runs when it is late
DL 1187 often beats the schedule: 108 of 354 completed flights, 31%, arrived 15 minutes or more early. The 105 late arrivals split 36 under half an hour, 25 between 30 and 60 minutes, and 44 an hour or more.
- 15+ min early108 flights30.5%
- Within 15 min141 flights39.8%
- 15–29 min late36 flights10.2%
- 30–59 min late25 flights7.1%
- 1–2 hours late27 flights7.6%
- 2+ hours late17 flights4.8%
Scale runs 0% to 100%.
Share of 354 completed flights by arrival against schedule.
24 of 114 late departures made up the time and arrived on time, 21% of them. 15 flights left on time and still arrived late.
The worst days
Worst days for DL 1187
The latest arrival of the period was on 29 December 2025, 11 hours 25 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 29 December 2025 | 11 hours 25 minutes | National Airspace System |
| 1 December 2025 | 5 hours 22 minutes | Carrier |
| 14 June 2026 | 3 hours 27 minutes | Carrier |
| 24 January 2026 | 2 hours 57 minutes | Carrier |
| 16 March 2026 | 2 hours 43 minutes | Late-arriving aircraft |
Delay causes
Why DL 1187 runs late
Carrier accounts for 48% of the 7,270 delay minutes carriers reported here, and the remaining four split what is left.
- 48%Carrier
- 26%National Airspace System
- 24%Late-arriving aircraft
- 2%Extreme weather
The largest share of delay minutes, 48%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,497 of the 7,270 delay minutes reported here. The split is drawn from 7,270 delay minutes reported on DL 1187.
Cancellations sit at 1.94% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
12.4% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 632 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.
Every one of the 361 flights under DL 1187 in the data flew DTW to BOS. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 361 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 1187
For a booking, DL 1187 is a flight to put a long connection behind. 12.4% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- DTW to BOS, every carrier and departure
- BOS to DTW, the return direction
- Delta Air Lines 1163 on the same route91.0%
- Delta Air Lines 2648 on the same route82.7%
- Delta Air Lines 1171 on the same route68.2%
- Delta Air Lines 1707 on the same route55.5%
- Detroit Metropolitan Wayne County (DTW) delay statistics
- Boston Logan International (BOS) 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
- How often a connection fails at the major US hubs
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.