Flight profile · Delta Air Lines
DL1540
Philadelphia (PHL) to Detroit (DTW) · scheduled 6:00 AM – 7:55 AM
How DL1540 performs
766 operations, June 2024 – July 2026.
DL1540 arrived on time 92.0% of the time, against 81.0% for all PHL → DTW flights, so this departure is 11.0 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 6.9 points better.
Source: US DOT Bureau of Transportation Statistics · 766 operations, June 2024 – July 2026 · If DL1540 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How DL1540 compares to other flight numbers, not just to itself.
This flight runs unusually far ahead of the PHL → DTW route as a whole, better than 92% of 11,788 comparable flight numbers.
92.0% on time for this specific departure, against 81.0% for every PHL → DTW flight.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where DL1540 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 |
|---|---|---|---|---|---|
| DL1540 | 92.0% | 1.96% | -17 min | 4.9% | 766 |
| Delta Air Lines on PHL → DTW | 85.1% | 1.48% | -15 min | 7.3% | 4,464 |
| All PHL → DTW flights | 81.0% | 2.31% | -11 min | 8.6% | 9,336 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL1540 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow 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 DL1540 on PHL → DTW. 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 DL1540 comes in late, and what that does to the departure.
DL1540 is usually the aircraft’s first flight of the day: the schedule gives it a median of 6.8 hours on the ground at PHL, so its “inbound” is mostly the aircraft’s arrival the evening before.
When the aircraft came in 15 or more minutes late, DL1540 pushed back an average of 23 minutes late; when it came in on time or early, an average of 3 minutes late.
Each departure is matched to the flight the same aircraft flew into PHL just before it, using the tail number in the DOT file, 742 of 752 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 | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| DL1540 | 20% | 17% | 6% |
| Network, same turn | 29% | 12% | 9% |
A night on the ground absorbs most of a late arrival, so a late inbound matters far less on a turn this long than on a same-day one.
The network row is every flight with a scheduled turn of 6 hours or more, usually overnight. How often DL1540’s aircraft landed 15 or more minutes late is lower than the network’s and, once the aircraft was late, how often DL1540 left 15 or more minutes late is higher than the network’s.
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 PHL late, does that still matter by the time it reaches DTW?
DL1540 pushes back an average of 7.3 minutes late and reaches the gate at DTW an average of 2.6 minutes early. The 9.9 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. It spends 14.4 minutes on the taxiways at PHL, 3.4 minutes shorter than a typical PHL departure in the same hour.
On arrival at DTW, DL1540 spends 7.8 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 1.5 minutes shorter than a typical DTW arrival (9.3 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 DTW. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 19,016 departures from PHL scheduled in the clock hour DL1540 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at DTW (388,616 flights), not just DL1540’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves PHL
Part of any flight’s record belongs to the clock rather than to the flight. DL1540 has one departure time, so this is what that time is worth.
On-time arrival rate. 19,016 departures from PHL are scheduled in the 6 AM–7 AM hour over the period, against 305,181 across the whole day.
DL1540 is scheduled out of PHL at 6:00 AM, in the 6 AM–7 AM bank. Departures from PHL in that hour arrive on time 87.0% of the time against 76.2% across the airport’s whole day — the slot alone is worth 10.8 points better before anything about this particular flight is considered.
The two airport figures cover every departure from PHL 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 DL1540 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 |
|---|---|---|---|
| LGA→BOS New York to Boston | April 9, 2024 – June 6, 2024 | 51 | — |
| SLC→DFW Salt Lake City to Dallas–Fort Worth | March 10, 2024 – April 8, 2024 | 30 | — |
| MSP→MCO Minneapolis to Orlando | January 8, 2024 – March 9, 2024 | 62 | — |
| MCO→MSP Orlando to Minneapolis | January 11, 2024 – March 9, 2024 | 50 | — |
| ATL→EWR Atlanta to Newark | December 16–30, 2023 | 13 | — |
| EWR→ATL Newark to Atlanta | December 16–30, 2023 | 13 | — |
| MSP→VPS Minneapolis to Valparaiso | November 5, 2023 – December 12, 2023 | 17 | — |
| VPS→MSP Valparaiso to Minneapolis | November 5, 2023 – December 12, 2023 | 17 | — |
| DEN→ATL Denver to Atlanta | November 20–27, 2023 | 2 | — |
| LAS→AUS Las Vegas to Austin | November 24, 2023 | 1 | — |
| HOU→ATL Houston to Atlanta | October 9, 2023 – November 4, 2023 | 27 | — |
| PDX→SEA Portland to Seattle | September 6, 2023 – October 8, 2023 | 33 | — |
| IAH→LAX Houston to Los Angeles | July 1, 2023 – September 4, 2023 | 60 | — |
Because the same number has served different journeys, the statistics above describe only the route DL1540 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.
6 min late
against a median of 17 min early
Percentiles over 766 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Data and methodology
Calculated by FlyerIntel from 766 records of DL1540 operating PHL → DTW, 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
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