Flight profile · Delta Air Lines
DL1171
Detroit (DTW) to Boston (BOS) · scheduled 2:00 PM – 3:53 PM
How DL1171 performs
780 operations, June 2024 – July 2026.
DL1171 arrived on time 71.3% of the time, against 76.7% for all DTW → BOS flights, so this departure is 5.4 percentage points worse than the route as a whole. Against Delta Air Lines’ own flights on this route it is 6.2 points worse.
Source: US DOT Bureau of Transportation Statistics · 780 operations, June 2024 – July 2026 · If DL1171 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
Where DL1171 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL1171 | 71.3% | 0.77% | -3 min | 11.0% | 780 |
| Delta Air Lines on DTW → BOS | 77.5% | 1.16% | -6 min | 8.6% | 5,258 |
| All DTW → BOS flights | 76.7% | 1.53% | -7 min | 9.5% | 8,286 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL1171 runs late
Where US DOT attributed the delay minutes on this flight.
airspace and airport capacity, including weather-driven flow control
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for DL1171 on DTW → BOS. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies DL1171 comes in late, and what that does to the departure.
The aircraft flying DL1171 came in 15 or more minutes late on 10% of the departures where its previous flight is known. There are not enough departures in both groups to say how the flight left after a late one and after an on-time one.
Each departure is matched to the flight the same aircraft flew into DTW just before it, using the tail number in the DOT file, 747 of 775 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late |
|---|---|
| DL1171 | 10% |
| Network, same turn | 17% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often DL1171’s aircraft landed 15 or more minutes late is lower than the network’s. There are not enough departures in both groups to compare how it left.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
From pushback to gate
When it leaves DTW late, does that still matter by the time it reaches BOS?
DL1171 pushes back an average of 16.4 minutes late and reaches the gate at BOS an average of 12.0 minutes late. The 4.4 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. Its 18.0 minutes on the taxiways at DTW is about what any departure from the airport in that hour spends.
On arrival at BOS, DL1171 spends 11.2 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 2.3 minutes longer than a typical BOS arrival (9.0 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached BOS. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 21,718 departures from DTW scheduled in the clock hour DL1171 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at BOS (440,886 flights), not just DL1171’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves DTW
Part of any flight’s record belongs to the clock rather than to the flight. DL1171 has one departure time, so this is what that time is worth.
On-time arrival rate. 21,718 departures from DTW are scheduled in the 2 PM–3 PM hour over the period, against 388,632 across the whole day.
DL1171 is scheduled out of DTW at 2:00 PM, in the 2 PM–3 PM bank. Departures from DTW in that hour arrive on time 77.3% of the time against 79.6% across the airport’s whole day, so the hour DL1171 leaves in is an ordinary one for DTW and explains nothing about its record either way.
The two airport figures cover every departure from DTW to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes DL1171 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| DTW→PWM Detroit to Portland | May 7, 2024 – June 5, 2024 | 30 | — |
| LGA→ATL New York to Atlanta | April 9, 2024 – May 6, 2024 | 24 | — |
| MCO→RDU Orlando to Raleigh–Durham | July 1, 2023 – April 8, 2024 | 220 | 74.8% |
| RDU→MCO Raleigh–Durham to Orlando | July 1, 2023 – April 8, 2024 | 195 | 77.3% |
| LAX→MSP Los Angeles to Minneapolis | January 8, 2024 – March 9, 2024 | 62 | — |
Because the same number has served different journeys, the statistics above describe only the route DL1171 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
63 min late
against a median of 3 min early
DL1171 has an average that understates its risk: a typical arrival is 3 min early, but the worst tenth are 66 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 780 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| DL1163 | Delta Air Lines | 90.8% | 13 min early | 782 |
| DL2648 | Delta Air Lines | 84.7% | 8 min early | 1,059 |
| B61336 | JetBlue | 79.1% | 8 min early | 690 |
| DL1171 this flight | Delta Air Lines | 71.3% | 3 min early | 780 |
| DL1187 | Delta Air Lines | 69.1% | 5 min early | 763 |
| B61136 | JetBlue | 60.3% | 1 min late | 639 |
| DL1707 | Delta Air Lines | 60.0% | 7 min late | 638 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL1171 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 780 records of DL1171 operating DTW → BOS, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed