Flight profile · Delta Air Lines
DL1231
New York (LGA) to Detroit (DTW) · scheduled 6:00 AM – 7:55 AM
How DL1231 performs
785 operations, June 2024 – July 2026.
DL1231 arrived on time 94.0% of the time, against 80.9% for all LGA → DTW flights, so this departure is 13.1 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 12.8 points better.
Source: US DOT Bureau of Transportation Statistics · 785 operations, June 2024 – July 2026 · If DL1231 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 DL1231 compares to other flight numbers, not just to itself.
This flight stays close to typical even on its worst days, a smaller gap than 98% of 11,788 comparable flight numbers.
A typical arrival is 10 min early, and the worst tenth are only 16 minutes worse than that.
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 DL1231 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
Ask for the position of DL1231 right now, if receivers on the ground are hearing it. Nothing is requested until you press the button.
Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL1231 | 94.0% | 3.95% | -10 min | 1.7% | 785 |
| Delta Air Lines on LGA → DTW | 81.2% | 2.14% | -11 min | 8.2% | 6,109 |
| All LGA → DTW flights | 80.9% | 3.07% | -11 min | 8.5% | 12,495 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL1231 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
Share of the delay minutes US DOT attributed to each cause for DL1231 on LGA → 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 DL1231 comes in late, and what that does to the departure.
DL1231 is usually the aircraft’s first flight of the day: the schedule gives it a median of 6.9 hours on the ground at LGA, so its “inbound” is mostly the aircraft’s arrival the evening before.
When the aircraft came in 15 or more minutes late, DL1231 pushed back an average of 1 minute late; when it came in on time or early, an average of 3 minutes early.
Each departure is matched to the flight the same aircraft flew into LGA just before it, using the tail number in the DOT file, 733 of 754 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 |
|---|---|---|---|
| DL1231 | 35% | 5% | 4% |
| 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 DL1231’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often DL1231 left 15 or more minutes late is lower 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 LGA late, does that still matter by the time it reaches DTW?
DL1231 pushes back an average of 1.3 minutes early and reaches the gate at DTW an average of 7.1 minutes early. The 5.7 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 18.6 minutes on the taxiways at LGA is about what any departure from the airport in that hour spends.
On arrival at DTW, DL1231 spends 8.6 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 about what any arrival at DTW spends on the ground before reaching the gate.
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 32,995 departures from LGA scheduled in the clock hour DL1231 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 DL1231’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves LGA
Part of any flight’s record belongs to the clock rather than to the flight. DL1231 has one departure time, so this is what that time is worth.
On-time arrival rate. 32,995 departures from LGA are scheduled in the 6 AM–7 AM hour over the period, against 456,467 across the whole day.
DL1231 is scheduled out of LGA at 6:00 AM, in the 6 AM–7 AM bank. Departures from LGA in that hour arrive on time 91.1% of the time against 78.3% across the airport’s whole day — the slot alone is worth 12.8 points better before anything about this particular flight is considered.
The two airport figures cover every departure from LGA 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 DL1231 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.
Because the same number has served different journeys, the statistics above describe only the route DL1231 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 10 min early
Percentiles over 785 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 |
|---|---|---|---|---|
| DL1231 this flight | Delta Air Lines | 94.0% | 10 min early | 785 |
| DL1078 | Delta Air Lines | 88.3% | 13 min early | 782 |
| DL1122 | Delta Air Lines | 80.5% | 11 min early | 780 |
| DL999 | Delta Air Lines | 70.8% | 5 min early | 784 |
| YX4598 | Republic Airways | 70.5% | 5 min early | 833 |
| DL1014 | Delta Air Lines | 64.3% | 7 min early | 644 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL1231 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 785 records of DL1231 operating LGA → 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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